© Author(s) 2023. CC Atribution 4.0 License Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Prečnodinarska cona povečane kompresije med Kraškim robom in Hrušico, NE Mikroadrija Ladislav PLACER 1 , Igor RIŽNAR 2 & Ana NOVAK 1 1 Geološki zavod Slovenije, Dimičeva ul. 14, SI-1000 Ljubljana, Slovenija; e-mails: ladislav.placer@telemach.net, ana.novak@geo-zs.si 2 Geološke ekspertize Igor Rižnar s. p., SI-1000 Ljubljana, Slovenija; e-mail: igor.riznar@telemach.net Prejeto / Received 21. 3. 2023; Sprejeto / Accepted 29. 6. 2023; Objavljeno na spletu / Published online 4. 8. 2023 Key words: NE Microadria (Adria Microplate), Istra peninsula, Istra Pushed Area, Črni Kal Anomaly, Kraški rob – Mt. Hrušica Traverse, stacked structure, envelope fault Ključne besede: NE Mikroadrija (Jadranska mikroplošča), Istra, istrsko potisno območje, črnokalska anomalija, traverza Kraški rob – Hrušica, zložbena zgradba, ovojni (envelopni) prelom Abstract The Kvarner fault divides the Microadria (Adria microplate, the Adria stable core) into the Po and Adria segments. The Istra block, which is sandwiched between the right-lateral Kvarner Fault and the left-lateral Sistiana Fault lies at the extreme eastern edge of the Po segment. Both faults run transversely to the Dinarides and reach their thrust boundary in the east. The Microadria has been moving towards the Dinarides since the Middle Miocene. The movement of the Istra block is exposed in relation to the neighbouring blocks, so an extensive pushed area (the Istra Pushed Area) was formed in the External Dinarides, which is bent towards the northeast. It is defined by two flexural zones, one lying in the extension of the Sistiana Fault and the other in the extension of the Kvarner Fault. The structure of the Dinaric thrust border on the north-eastern side of the Istra block is complex. Its prominent structural element is the Črni Kal Anomaly, due to which a zone of increased compression developed within the Istra Pushed Area and transversely to the Dinarides (Kraški rob – Hrušica Traverse), which lies between the Sistiana and Kvarner Flexural Zones. In terms of kinematics, it differs greatly from these two, and various geomorphologically responsive deformations have occurred within it. Mt. Vremščica (1027 m), which represents a transpressive anticline within the wider zone of the Raša Fault is the most prominent. In order to understand the genesis of the Classical Karst relief, it is important to know that the Mt. Vremščica ridge rose from the levelled karst surface. Izvleček Kvarnerski prelom deli Mikroadrijo (Jadranska mikroplošča, stabilno jedro Adrije) na padski in jadranski segment. Na skrajnem vzhodnem robu padskega segmenta leži istrski blok, ki je umeščen med desnozmični Kvarnerski in levozmični Sesljanskim prelom. Oba preloma potekata prečno na Dinaride in segata do njihove narivne meje. Mikroadrija se že od srednjega miocena naprej pomika proti Dinaridom, premikanje istrskega bloka je nasproti sosednjim blokom eksponirano, zato se je v Zunanjih Dinaridih izoblikovalo obsežno potisno območje (istrsko potisno območje), ki je usločeno proti severovzhodu. Določata ga dve upogibni coni, ena leži v podaljšku Sesljanskega, druga v podaljšku Kvarnerskega preloma. Zgradba narivne meje Dinaridov na severovzhodni strani istrskega bloka je zapletena, njen izstopajoči strukturni element je črnokalska anomalija, zaradi katere se je v istrskem potisnem območju in prečno na Dinaride razvila cona povečane kompresije (traverza Kraški rob - Hrušica), ki leži med sesljansko in kvarnersko upogibno cono. V kinematskem smislu od obeh močno odstopa, v njej so nastale različne geomorfološko odzivne deformacije, najbolj vidna med njimi je Vremščica (1027 m), ki predstavlja transpresivno antiklinalo znotraj širše cone Raškega preloma. Za razumevanje geneze reliefa Klasičnega krasa je pomembno vedeti, da se je greben Vremščice dvignil iz uravnanega kraškega površja. GEOLOGIJA 66/1, 9-71, Ljubljana 2023 https://doi.org/10.5474/geologija.2023.001 10 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Introduction Blašković & Aljinović (1981), and Blašković (1991; 1999) already showed that the Dinaric foot - hills in the Istra and Kvarner are moving towards the Dinarides, and a more specific structural justi - fication for the movement of Istra was given in the discussion on the basics of understanding the tec- tonics of the north-western Dinarides and Peninsu- la Istra (Placer et al., 2010) and in discussion of the Sistiana Fault and Sistiana Bending Zone (Placer et al., 2021b). In these discussions, it was established that Istra, which is part of the Microadria (Adriatic microplate), lies in a block (the Istra block) between two strike-slip faults: the left-lateral Sistiana Fault in the northwest and the complex right strike-slip Kvarner Fault in the southeast (Fig. 1). Both faults lie transversely to the Dinarides and extend only as far as the Dinaric Thrust Belt boundary. In the Dinarides, their influence is reflected in the clock- wise Sistiana and anticlockwise Kvarner Flexural Zones, which run in the direction of both faults. In this article, the term Sistiana Bending Zone is re - placed by the term Sistiana Flexural Zone because it better corresponds to the tectonic terminology. The part of the Microadria northwest of the Sistia - na Fault was designated as the Friuli block, which is less exposed to the Dinarides than the Istra block. The movement of the Istra block is compensated by the lateral bending of the External Dinarides to - wards the northeast and by underthrusting in the area of their thrust boundary. This is how the Is - tra-Friuli Thrust-Underthrust Zone and the Istra Pushed Area, defined by both flexural zones, were formed. The process of pushing is more important Uvod Da se Dinarsko predgorje na območju Istre in Kvarnerja premika proti Dinaridom sta opozori - la že Blašković in Aljinović (1981) ter Blašković (1991; 1999), določnejša strukturna utemeljitev premikanja Istre pa je bila podana v razpravi o osnovah razumevanja tektonike severozaho - dnih Dinaridov in Istre (Placer et al., 2010) ter v razpravi o Sesljanskem prelomu in sesljanski upogibni coni (Placer et al., 2021b). V teh raz - pravah je bilo ugotovljeno, da leži Istra, ki je del Mikroadrije (Jadranske mikroplošče), v bloku (istrski blok) med dvema zmičnima prelomoma, levozmičnim Sesljanskim prelomom na severo - zahodu in desnozmičnim Kvarnerskim prelo - mom na jugovzhodu. Oba preloma ležita prečno na smer Dinaridov in segata le do njihove na - rivne meje. V Dinaridih se njun vpliv odraža v levosučni sesljanski in desnosučni kvarnerski upogibni coni, ki potekata v smeri obeh prelo - mov. Del Mikroadrije severozahodno od Sesljan - skega preloma je bil označen kot furlanski blok, ki pa je proti Dinaridom manj izpostavljen od istrskega bloka. Premikanje istrskega bloka je kompenzirano z bočnim upogibom Zunanjih Di - naridov proti severovzhodu in s podrivanjem v območju njihove narivne meje. Tako sta nastala istrsko-furlanska podrivna cona in istrsko po- tisno območje, ki ga določata obe upogibni coni. Proces potiskanja je pomembnejši od podriva - nja. V podrivni coni naj bi se paleogenski na - rivi, ki označujejo konec dinarske narivne faze, transformirali v neogenske do recentne podri - ve. Recentno dviganje krovnih grud v območju Fig. 1. Tectonic subdivision of Istra penninsula and its Dinaric hinterland. Updated after Placer et al. (2010, Fig. 3; 2021b, Fig. 1). Sl. 1. Tektonska rajonizacija polotoka Istre in dinarskega zaledja. Dopolnjeno po Placer et al. (2010, sl. 3; 2021b, sl. 1). 1 Dinarides. External Dinaric Thrust Belt: T – Trnovo Nappe, H – Hrušica Nappe, S – Snežnik Nappe / Dinaridi. Zunanjedinarski narivni pas: T – Trnovski pokrov, H – Hrušiški pokrov, S – Snežniški pokrov 2 Dinarides. External Dinaric Imbricated Belt / Dinaridi. Zunanjedinarski naluskani pas 3 Microadria: stable core, imbricated borderland (autochton sensu lato) / Mikroadrija: stabilno jedro, naluskano obrobje (avtohton sensu lato) 4 Microadria: stable core (autochton sensu stricto) / Mikroadrija: stabilno jedro (avtohton sensu stricto) 5 Southern Alps / Južne Alpe 6 Southern Alps thrust boundary / narivna meja Južnih Alp 7 External Dinaric Thrust Belt boundary, nappe bondary / meja Zunanjedinarskega narivnega pasu, meja pokrova 8 Thrust plane within Dinaric thrust boundary / nariv v coni narivne meje Dinaridov 9 Istra-Friuli Thrust-Underthrust Zone (Placer et al., 2010, Istra-Friuli Underthrust Zone) / istrsko-furlanska narivno-podrivna cona (Plac - er et al., 2010, istrsko-furlanska podrivna cona) 10 BuF – Buje reverse Fault / BuF – Bujski reverzni prelom 11 Anticlinoria: a – Čičarija Anticlinorium, b – Trieste-Komen Synclinorium, c – Ravnik Anticlinorium / antiklinoriji: a – Čičarijski antiklinorij, b – Tržaško-Komenski antiklinorij, c – Ravenski antiklinorij 12 Synclinoria: d – Brkini Synklinorium, e – Vipava Synclinorium / sinklinoriji: d – Brkinski sinklinorij, e – Vipavski sinklinorij 13 Important sub-vertical fault: SF – Sistiana Fault, KF – Kvarner Fault, RF – Raša fault, IF – Idrija Fault / pomembnejši subvertikalni prelom: SF – Sesljanski prelom, KF – Kvarnerski prelom, RF – Raški prelom, IF – Idrijski prelom 14 Microadria structural block: A – Istra block (A1 – South Istra Structural Wedge, A2 – North Istra Structural Wedge), B – Friuli block / strukturni blok Mikroadrije: A – istrski blok (A1 – južnoistrski strukturni klin, A2 – severnoistrski strukturni klin), B – furlanski blok 15 Relative movement direction of the fault block / relativna smer premika prelomnega krila 16 General direction of South Istra Structural Wedge movement / generalna smer premikanja južnoistrskega strukturnega klina 11 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria IF RF SF KF a c b d e A 1 B T H S A BuF A 2 LJUBLJANA RIJEKA Ilirska Bistrica Vremščica PORDENONE K V A R N E R A D R I A T I C S E A S O U T H E R N A L P S UDINE 2 15 1 T, H, S 5 6 10 BuF 11 a, b, c 12 d, e 13 SF, KF, RF, IF 14 A (A , 1 A 2 ) B 7 T H 9 16 8 4 3 Fig. 13 Fig. 11 0 10 20 km TRIESTE I S T RA 12 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK than underthrusting. In the underthrust zone, the Paleogene thrusts, which mark the end of the Di - naric thrust phase, are supposed to transform into Neogene to recent thrusts. The recent uplift of the Paleogene nappes in the Istra-Friuli Thrust-Under - thrust Zone was determined in Istra by the ream - bulation of levelling lines (Rižnar et al., 2007). Istra is a visible part of the Istra block, divid- ed into the South Istra and North Istra Structural Wedges (Fig. 1). According to the established direc - tions of movement and parallel deformations, the South Istra Structural Wedge should move towards the Dinarides faster than the northern one. The above-mentioned fundamental findings stimulated a series of focused researches: the re - cent movement of Istra towards the Dinarides was proven by GPS measurements (Weber et al., 2010), the more intense movement of the tip of the South Istra Structural Wedge towards the Dinarides was confirmed by measurements of the local rotation of magnetic poles in cave sediments in the thrust units of the Dinarides (Vrabec et al., 2018); large sub-recent gravity phenomena in the area of the Istra Pushed Area were investigated (Placer et al., 2021a), and more precisely the Sistiana Flexural Zone was investigated (Placer et al., 2021b). Publi - cations regarding the seismicity of the area in ques - tion are not covered here. Geophysical surveys of the seabed of the Gulf of Trieste have shown that the mapped structures from Istra continue to the northwest. In this sense, the articles published after the discovery of the Buzet Thrust (Placer et al., 2004), which forms the south-western border of the Istra-Friuli Thrust-Un - derthrust Zone, are important. The subsea struc - ture is shown in the articles by Carulli (2006; 2011), Busetti et al. (2010a; 2010b; 2012; 2013), Trobec et al. (2017), and Novak et al. (2020). The findings of the aforementioned research are shown in Figure 1 within the structure of this part of the Dinarides. When studying the geomorphology of the Istra Pushed Area, it was shown that the movement of the Istra block caused not only lateral faulting, but also contraction of the Dinarides. Thus, the folds folded more intensively, and the blocks adapted to the con - traction by moving along the existing discontinu - ities. Therefore, it is necessary to solve the structure of geological objects within the Pushed Area in two stages: firstly, the structural geometry in the Paleo - gene at the end of thrusting must be determined, and then the successive deformations that occurred during the phase of Neogene-recent thrusting ac- cording to the Paleogene structural pre-set. Among the studied features, e.g. Kras (Trieste-Komen istrsko-furlanske podrivne cone, je bilo v Istri ugotovljeno z reambulacijo nivelmanov (Rižnar et al., 2007). Istra je vidni del istrskega bloka, razdeljena na južnoistrski in severnoistrski strukturni klin (sl. 1). Po ugotovljenih smereh gibanja in vzpore - dnih deformacijah, naj bi se južnoistrski struk - turni klin premikal proti Dinaridom hitreje od severnega. Zgoraj omenjene temeljne ugotovitve so vzpod - budile vrsto usmerjenih raziskav: z meritvami GPS je bilo dokazano recentno premikanje Istre proti Dinaridom (Weber et al., 2010), intenzivnejše pre - mikanje konice južnoistrskega strukturnega klina proti Dinaridom je bilo potrjeno z meritvami lokal - ne rotacije magnetnih polov v jamskih sedimentih, ki ležijo v narivnih enotah Dinaridov (Vrabec et al., 2018), raziskani so bili veliki subrecentni gravita - c ijsk i p ojav i v obmo č ju i s t r ske ga p ot i sne ga obmo č ja (Placer et al., 2021a), natančneje je bila raziskana sesljanska upogibna cona (Placer et al., 2021b). Objave o seizmiki obravnavanega prostora tu niso zajete. Geofizikalne raziskave podmorja Tržaškega zaliva so pokazale, da se kartirane strukture iz Istre nadaljujejo proti severozahodu. V tem smis - lu so pomembni članki, ki so bili objavljeni po odkritju Buzetskega nariva (Placer et al., 2004), ki tvori jugozahodno mejo istrsko-furlanske pod - rivne cone. Zgradbo podmorja prikazujejo članki Carulli-ja (2006; 2011), Busetti-jeve in sodelav - cev (2010a; 2010b; 2012; 2013), Trobčeve in sode - lavcev (2017) in Novakove in sodelavcev. (2020). Ugotovitve omenjenih raziskav so v okviru zgradbe tega dela Dinaridov prikazane na sliki 1. Pri proučevanju geomorfologije istrskega po - tisnega območja se je pokazalo, da premikanje istrskega bloka ni povzročilo le bočne usločit - ve, temveč tudi krčenje Dinaridov. Tako so se gube intenzivneje nagubale, bloki pa so se krče - nju prilagodili s premiki po obstoječih diskon - tinuitetah. Zato je potrebno zgradbo geoloških objektov znotraj potisnega območja reševati dvostopenjsko, najprej je treba določiti struktur - no geometrijo v paleogenu ob koncu narivanja, potem pa nasledstvene deformacije, ki so nastale v fazi neogensko-recentnega potiskanja po pale- ogenskem strukturnem predrisu. Izmed prouče - nih objektov, npr. Krasa (Tržaško-Komenskega antiklinorija), Škocjanskih jam, Brkinov (Brkin - skega sinklinorija) ali Čičarije (Čičarijskega an - tiklinorija), po kompleksnosti dogajanja izstopa osameli hrbet Vremščice (1027 m). V tej razpravi je opisano zaporedje deformacij, ki je privedlo do nastanka omenjenega hrbta. 13 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Anticlinorium), Škocjan ca v es, B r kini ( B r kini Syn - clinorium) or Čičarija (Čičarij a Anticlinorium), the isolated ridge of Mt. Vremščica (1027 m) stands out in terms of complexity. This discussion describes the sequence of deformations that led to the forma - tion of the aforementioned ridge. Instead of the term Istra-Friuli Underthrust Zone, the term Istra-Friuli Thrust-Underthrust Zone is used in this discussion, which better illus- trates the role of this zone in the process of Paleo- gene thrusting and Neogene-recent underthrusting. The structural geometry, kinematics, and geomorphology of Istra The visible part of Istra consists of the South Istra (A 1 ) and North Istra Structural Wedges (A 2 ), which rest on the Istra-Friuli Thrust-Un - derthrust Zone (Fig. 1). Due to the movement of this part of Microadria, and thus also Istra, both units behave differently towards the Dinarides, so it makes more sense to name them according to their dynamic characteristics. Thus, we introduce the terms South Istra Pushed Wedge and North Is - tra Extrusion Wedge (Fig. 2): the first moves with its tip towards the Dinarides, while the other is being extruded to the northwest towards the Gulf of Trieste. Both of them created corresponding structural and resulting geomorphological forms. The boundaries of the two dynamic units are not entirely identical to their formal structural bound - aries on the surface, so the designation Ad 1 is in- troduced for the South Istra Pushed Wedge, and Ad 2 for the North Istra Extrusion Wedge. South Istra Pushed Wedge Ad 1 The South Istra Structural Wedge is bounded by the Buje reverse Fault in the north, and in the east by the Kvarner Fault and the segment of the out - er boundary of the Istra-Furlania Thrust-Under - thrust Zone between the Kvarner and Buje Faults. It is built of Jurassic, Cretaceous, Paleocene, and Eocene carbonate rocks and Eocene clastics. The bedding forms a gently buckled anticline, the axis of which plunges very gently to the east-northeast, but its direction is impossible to determine precise - ly because the dip of the bedding is so low. Given the location of the anticline between the Buje and Kvarner Faults, where the main geomorphological object is the Limska draga (Lim channel/dry val - ley), it is called the Lim Anticline. It should not be confused with the north–south trending West Istra Anticline, which lies offshore, west of Istra. The Lim Anticline is discussed in more detail later. A closer examination of the structural wedge boundaries showed that the reverse Buje Fault Namesto izraza istrsko-furlanska podrivna cona, je v tej razpravi uporabljen izraz istrsko- -furlanska narivno-podrivna cona, ki bolje po- nazarja vlogo te cone v procesu paleogenskega narivanja in neogensko-recentnega podrivanja. Strukturna geometrija, kinematika in geomorfologija Istre Vidni del Istre sestavljata južnoistrski (A 1 ) in severnoistrski strukturni klin (A 2 ), ki se nasla - njata na istrsko-furlansko narivno-podrivno cono (sl. 1). Obe enoti se zaradi premikanja tega dela Mikroadrije, in s tem tudi Istre, proti Dina - ridom, obnašata različno, zato ju je smiselneje imenovati tudi po njunih dinamskih značilno - stih, tako uvajamo termina južnoistrski potisni klin in severnoistrski iztisni klin (sl. 2), prvi se s konico premika proti Dinaridom, drugi pa se iztiska (izriva) na severozahod proti Tržaškemu zalivu. Oba sta pri tem ustvarila ustrezne struk - turne in iz njih izhajajoče geomorfološke oblike. Meje obeh dinamičnih enot niso povsem iden - tične z njunimi formalnimi strukturnimi mejami na površini, zato je za južnoistrski potisni klin uvedena oznaka Ad 1 , za severnoistrski iztisni klina pa Ad 2 . Južnoistrski potisni klin Ad 1 Južnoistrski strukturni klin je na severu omejen z Bujsk im reverznim prelomom, na v zho - du pa s Kvarnerskim prelomom in segmentom zunanje meje istrsko-furlanske narivno-pod - rivne cone med Kvarnerskim in Bujskim prelo - mom. Zgrajen je iz karbonatnih kamnin jurske, kredne, paleocenske in eocenske starosti ter iz eocenskih klastitov. Plasti tvorijo rahlo usloče - no antiklinalo, katere os zelo blago tone proti vzhodu do severovzhodu, vendar je njeno smer natančneje nemogoče določiti, ker je vpad plasti majhen. Glede na lego antiklinale med Bujskim in Kvarnerskim prelomom, kjer je glavni geo - morfološki objekt Limska draga, jo imenujemo Limska antiklinala. Menimo, da je ne smemo za - menjevati z Zahodnoistrsko antiklinalo, ki leži v podmorju zahodno od Istre v smeri sever-jug. Limska antiklinala bo natančneje obravnavana pozneje. Natančnejši pregled mej strukturnega klina je pokazal, da Bujski reverzni prelom ne kaže znakov sekundarnega premikanja, vendar ga na zahodu seka Zambratijski prelom in več nje - mu vzporednih za katere domnevamo, da nap - rej proti vzhodu-jugovzhodu potekajo južno od Bujskega preloma. Zambratijski prelom ima vi - dne horizontalne drse (sl. 2, točka 1; sl. 5/1) iz 14 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Isonzo Soča Rižana Dragonja Mirna Butoniga Pazinčica Raša Boljunčica Rokava Pivka Reka L i m s k a d r a g a SECTION Fig. 3 J+K+Pc+E Al E Fig. 4 PROFILE Fig. 12 RIJEKA PAZIN d 1 ViA d 2 3 d 1, d 2, 3 SbA ZrF ZaF ZaF 0 10 20 km Fig. 2. Istra structural sketch and hydrographic network. Sl. 2. Strukturna skica Istre in hidrografska mreža. 15 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria shows no signs of secondary movement, but it is cut in the west by the Zambratija Fault and several par - allel ones, for which we assume continue south of the Buje Fault to the east-southeast. The Zambrati - ja Fault has visible horizontal slickensides (Fig. 2, point 1; Fig. 5/1), from which it was not possible to determine the direction of the movement. It was determined on the basis of the rotation of the paleo - magnetic poles in the vicinity of the fault, from which it indirectly follows that it is a left lateral strike- slip fault (Placer et al., 2010, fig. 4). The reverse Buje Fault did not become a left-lateral strike-slip, probably due to its uneven horizontal cross-section, which is manifested in a large bulge-like protrusion north of the lower Mirna River, which inhibited its movement. The Istra-Friuli Thrust-Underthrust Zone is morphologically strongly expressed in east - ern Istra and runs almost parallel to the eastern Istrian coast, and thus also parallel to the Kvarner Fault. From the viewpoint above the Flanona Hotel in Plomin (Fig. 2, point 2), a south-easterly dipping fault plane (110/30) with prominent subhorizontal slickenides (Fig. 5/2), indicating dextral strike-slip (Placer et al., 2010, fig. 4) were found. It is obvious - ly a Paleogene thrust plane rotated clockwise along the right strike-slip Kvarner Fault in the Neogene and then transformed into a strike slip fault plane. From these facts follows that the left-lateral strike- slip Zambratija Fault and several parallel ones formed next to the reverse Buje Fault, from which the left-lateral strike-slip Zambratija Zone was formed. Along the right-lateral strike-slip Kvarner Fault, the Istra-Friuli Thrust-Underthrust Zone bent to the south-southwest and became parallel to katerih pa ni bilo mogoče ugotoviti smisla pre - mika, ta je bil določen na podlagi rotacije pale - omagnetnih polov v bližini preloma iz česar po - sredno izhaja, da gre za levo zmikanje (Placer et al., 2010, sl. 4). Bujski reverzni prelom ni pos - tal levozmični verjetno zato, ker mu je to prep - rečeval njegov neravni horizontalni presek, ki se kaže v veliki trebušasti izboklini severno od spodnje Mirne. Istrsko-furlanska narivno-pod - rivna cona je v vzhodni Istri morfološko močno izražena in poteka skoraj vzporedno z vzhodno obalo Istre, s tem pa tudi s Kvarnerskim pre - lomom. Na razgledišču nad hotelom Flanona v Plominu (sl. 2, točka 2) je bila odkrita ploskev v smeri 110/30 z izrazitimi subhorizontalnimi drsami (sl. 5/2), ki kažejo na desno zmikanje (Placer et al., 2010, sl. 4). Očitno gre za paleo - gensko narivno ploskev, ki je bila v neogenu ob desnozmičnem Kvarnerskem prelomu zasukana v smeri urinega kazalca in nato transformirana v zmično ploskev. Iz dejstev torej izhaja, da je ob Bujskem reverznem prelomu nastal Zambra - tijski levozmični prelom in nekaj njemu vzpo - rednih, iz katerih se je oblikovala zambratijska levozmična cona. Ob Kvarnerskem desnozmič - nem prelomu se je istrsko-furlanska narivno - -podrivna cona upognila proti jugo-jugozahodu in se postavila vzporedno s prelomom. Nastala je kombinirana kvarnerska desnozmična cona. Da obstaja južnoistrski potisni klin potrjujejo tudi podatki paleomagnetnih raziskav jamskih sedimentov v Čičariji, ki kažejo na levo in desno krajevno omejeno rotacijo enot istrsko-furlanske narivno-podrivne cone. Konica klina je delovala 1 J + K + Pc + E – Jurassic, Cretaceous, Paleocene, and Eocene carbonates, E – Eocene flysch, Al – aluvium. Bedding strike and dip / J + K + Pc + E – jurski, kredni, paleocenski in eocenski karbonati, E – eocenski fliš, Al – aluvij. Vpad plasti 2 External Dinaric Thrust Belt boundary / meja Zunanjedinarskega narivnega pasu 3 Thrust plane within Dinaric thrust boundary: BuF – reverse Buje Fault, BT – Buzet Thrust / nariv v coni narivne mejne Dinaridov: BuF – Bujski reverzni prelom, BT – Buzetski narivni prelom 4 Strike-slip fault in the Microadria area: SF – Sistiana Fault, KF – Kvarner Fault / zmični prelom v območju Mikroadrije: SF – Sesljanski prelom, KF – Kvarnerski prelom 5 Lateral strike-slip faults: ZaF – Zambratija Fault, ZrF – Zrenj Fault / zmični prelomi: ZaF – Zambratijski prelom, ZrF – Zrenjski prelom 6 Istra-Friuli Thrust-Underthrust Zone / istrsko-furlanska narivno-podrivna cona 7 Neogene-recent right lateral strike-slip movements in the Paleogene thrust zone / desnozmični neogensko-recentni premiki v paleogenski narivni coni 8 Right lateral strike-slip fault in the Črni Kal Anomaly / desnozmični prelom v črnokalski anomaliji 9 Anticlines: LA – Lim Anticline, SbA – Savudrija-Buzet Anticline, ViA – East Istra Anticline / antiklinale: LA – Limska antiklinala, SbA – Savudrijsko-Buzetska antiklinala, ViA – Vzhodnoistrska antiklinala 10 Profile in Fig. 12 / Profil na sl. 12 11 North Istra Extrusion Wedge extrusion boundary / meja iztiskanja severnoistrskega iztisnega klina 12 Istra block: Ad1 – South Istra Pushed Wedge, Ad2 – North Istra Extrusion Wedge, A3 – Trieste parallelepiped / istrski blok: Ad1 – južnoistrski potisni klin, Ad2 – severnoistrski iztisni klin, A3 – tržaški paralelepiped 13 Observed evidence of strike-slip movement: 1 – Zambratija, 2 – Flanona / mesta vidnih dokazov zmikanja: 1 – Zambratija, 2 – Flanona 14 Strike–slip in the section in Fig. 3: left lateral strike-slip, right lateral strike-slip / zmični premik v profilu na sl. 3: levozmični prelom, desnozmični prelom 15 General direction of pushing, extrusion / generalna smer potiskanja, iztiskanja 16 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK the fault. Thus, a combined right-lateral strike-slip Kvarner Zone was formed. The existence of the South Istra Pushed Wedge is also confirmed by the data from paleomagnetic research of the cave sediments in Čičari ja, which indicate left and right locally limited rotation of the units of the Istra-Friuli Thrust-Underthrust Zone. The tip of the wedge worked so that the thrust units in front of it bent, with some rotating to the left and some to the right (Vrabec et al., 2018). The structure of the South Istra Pushed Wedge is given in the sketch of the Lim Anticline cross-sec - tion in Figure 3, where the simplified structures of the Zambratija and Kvarner shear zones, and the Lim Anticline with the dry Limska draga are pre - sented in dark hatch, and the surface flows of Mirna River with Butoniga and Raša River with Boljunčica are present in the anticline limbs. The reverse Buje Fault abuts on the Zambratija Fault at depth, with its left-lateral movement related to the Zambratija Fault or to its zone. The Kvarner Fault abuts on the outer border of the Istra-Friuli Thrust-Underthrust Zone, with dextral displacement along the Kvarner Fault and along the transformed segment of the Is - tra-Friuli Thrust-Undrethrust Zone. We cannot yet speak more precisely about the age of the individual structural elements and geo - morphology of the South Istra Pushed Wedge, but we can determine the sequence of their formation. There was no deposition in Istra in the Oligocene (Basic Geological Map - OGK sheets: Trieste, Il - irska Bistrica, Rovinj, Labin, Pula, Cres), so we assume that the area rose to the surface at the be - ginning of the Oligocene and a period of erosion tako, da so se narivne enote pred njo upognile, del se je zasukal v levo, del pa v desno (Vrabec et al., 2018). Zgradba južnoistrskega potisnega klina je po - dana v skici prečnega prereza Limske antiklina - le na sliki 3, tu se vidi poenostavljeni strukturi zambratijske in kvarnerske zmične cone, Limsko antiklinalo s suho Limsko drago v temenu in po - vršinska tokova Mirne z Butonigo in Raše z Bo - ljunčico v krilih gube. Na Zambratijski prelom se v globini naslanja Bujski reverzni prelom, levoz - mični premik je vezan na prvega, oziroma na nje - govo cono. Kvarnerski prelom se naslanja na zu - nanjo mejo istrsko-furlanske narivno-podrivne cone, desnozmični premik se dogaja ob Kvarner - skem prelomu in ob transformiranem segmentu istrsko-furlanske narivno-podrivne cone. O starosti posameznih elementov struktu - re in geomorfologije južnoistrskega potisnega klina še ne moremo natančneje govoriti, lahko pa določimo zaporedje njihovega nastajanja. V Istri niso bile odložene oligocenske plasti (OGK, listi: Trst, Ilirska Bistrica, Rovinj, La - bin, Pula, Cres), zato domnevamo, da se je v začetku oligocena območje dvignilo na površje in pričelo se je obdobje erozije v katerem se je izoblikovala primarna rečna mreža. Pričetek premikanja Mikroadrije proti Dinaridom še ni natančneje določen, domnevamo, da se je začelo v srednjem miocenu, kljub temu pa lahko razp - ravljamo o zaporedju dogodkov. Zaradi napre - dovanja klina med konvergentnima prelomoma (Kvarnerski prelom, Zambratijski prelom) pro - ti severo severovzhodu je pričela rasti Limska SOUTH ISTRA PUSHED WEDGE EAST ISTRA ANTICLINE SAVUDRIJA- BUZET ANTICLINE Limska draga Dry Valley NOT TO SCALE Fig. 3. Lim Anticline transver - sal cross section. Cross section trace in Figure 2. Legend in Figure 2. Sl. 3. Skica prečnega profila Limske antiklinale. Potek pro - fila na sl. 2. Legenda na sliki 2. 17 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria began, during which the primary river network (was) formed. The beginning of the Microadria movement towards the Dinarides is not yet pre - cisely determined. It is assumed that it started in the middle Miocene; however, we can discuss the sequence of events. Due to the progress of the wedge between the convergent faults (Kvarner Fault, Zambratija Fault) towards the north-north - east, the Lim Anticline began to grow, and the Paleo-Mirna and Paleo-Raša flows, which were directed along the thrust wedge shear boundar- ies, submitted to its geometry. The Paleo-Pazinči - ca River flow, however, remained trapped in the crest of the anticline where it carved a deep val- ley. The karst surface peneplanation of southern Istra is today slightly buckled, as its uplift along the anticline axis was faster than the erosion of the Paleo-Pazinčica, which is why it retreated un - derground. The process of formation of the current geomorphological image of the South Istra Pushed Wedge was either continuous or multi-stage, but without detailed research it is impossible to deter - mine this. The South Istra Pushed Wedge geometry and dynamics are also strengthened by the springs of the most important rivers at its tip, Mirna and Bu - toniga rivers, Raša with its former tributary the Boljunčica river, and Pazinčica. In the immediate hinterland of the pushed wedge tip is the highest peak of Čičari ja, Mt. Veli - ki Planik (1272 m). Nearby is Mt. Vojak (1394 m), Mt. Učka’s peak, which lies in the East Istra Anti - cline. It was formed from multiple structural units as a consequence of Paleogene thrusting and sub - sequent Neogene to recent movements along the Kvarner Fault. North Istra Extrusion Wedge Ad 2 Formally, the North Istra Structural Wedge (Figs. 2 and 4A) is a unit between the reverse Buje Fault (BuF) and the Istra-Friuli Thrust-Under - thrust Zone, more precisely the Buzet thrust Fault (BT), along its south-western border. The reverse Buje Fault lies under the Istra-Friuli Thrust-Un - derthrust Zone in the Buzet area. This point for - mally represents the tip of the wedge. The North Istra Structural Wedge is built of Cretaceous, Paleocene, and Eocene carbonates overlain by Eocene clastites; carbonates are exposed in the Savudrija-Buzet Anticline, which is an accom - panying structure of the reverse Buje Fault, and in the tectonic window or half-window at Izola, which is an accompanying structure of the Križ Thrust (KT). The flysch beds plunge below the Is - tra-Friuli Thrust-Underthrust Zone. antiklinala, njeni geometriji sta se podredi - la tokova paleo-Mirne in paleo-Raše, ki sta se usmerila vzdolž zmičnih meja potisnega kli - na, tok paleo-Pazinčice pa je ostal ujet v teme - nu antiklinale kjer je urezoval globoko dolino. Kraška uravnava južne Istre je danes rahlo usločena, njeno dviganje je bilo v osi antikli - nale hitrejše od erozije paleo-Pazinčice, zato se je ta umaknila v podzemlje. Proces nastajanja sedanje geomorfološke podobe južnoistrskega potisnega klina je bil ali kontinuiran ali večsto - penjski, brez detajlnih raziskav tega ni mogoče ugotoviti. Geometrijo in dinamiko južnoistrskega poti - snega klina utrjujejo tudi izviri pomembnejših rek v njegovi konici, Mirne in Butonige, Raše z nekdanjim pritokom Boljunčico in Pazinčice. V neposrednem zaledju konice potisnega kli - na se nahaja najvišji vrh Čičarije, Veliki Planik (1272 m). V bližini je vrh Učke, Vojak (1394 m), ki pa leži v Vzhodnoistrski antiklinali. Ta je sestavljena iz več strukturnih enot in je nastala v prepletu učinkov paleogenskega narivanja in neogensko-recentnih premikov ob Kvarnerskem prelomu. Severnoistrski iztisni klin Ad 2 Severnoistrski strukturni klin (sl. 2 in 4A) je v formalnem smislu enota med Bujskim re - verznim prelomom (BuF) in istrsko-furlansko narivno-podrivno cono, natančneje Buzetskim narivnim prelomom (BT), ki leži na njeni ju - gozahodni meji. Na območju Buzeta leži Bujski reverzni prelom pod istrsko-furlansko narivno - -podrivno cono. Ta točka formalno predstavlja konico klina. Severnoistrski strukturni klin je zgrajen iz krednih, paleocenskih in eocenskih karbonatov, ki jih prekrivajo eocenski klastiti; karbonati izdanjajo v Savudrijsko-Buzetski an - tiklinali, ki je spremljajoča struktura Bujskega reverznega preloma in v tektonskem oknu ali poloknu v Izoli, ki je spremljajoča struktura Križnega narivnega preloma (KT). Flišne plasti tonejo pod istrsko-furlansko narivno-podrivno cono. V dinamičnem smislu je južna meja sever - noistrskega iztisnega klina identična s severno mejo južnoistrskega potisnega klina, obstaja pa možnost, da je poleg zambratijske levozmične cone levozmično aktiven tudi Zrenjski prelom na severni strani Savudrijsko-Buzetske antiklinale. Severovzhodna meja severnoistrskega iztisnega klin pa ni identična z Buzetskim narivnim pre - lomom, temveč poteka poševno na do 12 km ši- roko istrsko-furlanske narivno-podrivne cono, 18 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK In a dynamic sense, the southern border of the North Istra Extrusion Wedge is identical to the northern boundary of the South Istra Pushed Wedge, but there is a possibility that, in addition to the strike-slip Zambratija Zone, the Zrenj Fault on the north side of the Savudrija-Buzet Anticline is active as well. The north-eastern border of the North Istra Extrusion Wedge is not identical to the Buzet Thrust, but runs obliquely to the 8 to 12 km- wide Istra-Friuli Thrust-Underthrust Zone, ap - proximately from the upper Mirna to the lower Glinščica/Rosandra rivers in a SSE-NNW direc - tion. This boundary is not represented by only one structural element, but rather by a complex fault zone in which subvertical faults in the SSE-NNW direction are the most important (Figs. 2 and 4A). Before describing the zone between the upper Mirna and lower Glinščica/Rosandra rivers, let’s look at the most important signs of lateral thrusting within the North Istra Extrusion Wedge (Figs. 2 and 4A). The most important is the normal Rokava Fault, which runs transversely to the wedge and in- dicates the direction of extrusion towards the Gulf of Trieste. The middle Dragonja and Rokava valleys were formed along the Rokava Fault (Placer et al. 2004; Placer, 2005). A large part of the upper Drag - onja valley also runs transversely to the extrusion približno od zgornje Mirne do spodnje Glinščice v smeri SSE-NNW. Te meje ne predstavlja le en element strukture, temveč kompleksna prelom - na cona v kateri so najpomembnejši deznozmični subvertikalni prelomi v smeri SSE-NNW (sl. 2 in 4A). Preden opišemo cono med zgornjo Mirno in spodnjo Glinščico, si oglejmo najpomembnejše znake bočnega izrivanja znotraj severnoistrske - ga iztisnega klina (sl. 2 in 4A); na prvem mestu je Rokavin normalni prelom, ki poteka prečno na klin in kaže na smer iztiskanja proti Trža - škemu zalivu. Po njem sta se izoblikovali dolini srednje Dragonje in Rokave (Placer et al., 2004; Placer, 2005). Prečno na iztisni klin poteka tudi večji del doline zgornje Dragonje in pa številne doline potokov, ki med srednjo Dragonjo in Bra - čano ponikajo v apnencu Savudrijsko-Buzetske antiklinale. Prečno na klin teče tudi srednja Mirna preko Savudrijsko-Buzetske antiklinale. Severozahodno od Rokavinega preloma ne pre - vladujejo več prečne doline, tu so spodnja Dra - gonja, Drnica, Badaševica, Rižana in Osapska reka poglobile svoje struge po drugih elementih strukture. Glede na to izgleda, da se je severo - zahodni del klina iztisnil kot sorazmerno ho - mogen blok. Fig. 4. North Istra Extrusion Wedge: A. North Istra structural sketch (updated and symplified after Placer, 2005, Fig. 1; 2007, Fig. 2; Placer et al., 2010, Fig. 5). B. Neogene to recent extrusion evidence in the northern Istra relief. Sl. 4. Severnoistrski iztisni klin: A. Strukturna skica severne Istre (dopolnjeno in poenostavljeno po Placer, 2005, sl. 1; 2007, sl. 2; Placer et al., 2010, sl. 5). B. Znaki neogensko-recentnega iztiskanja v reliefu severne Istre. 1 K + Pc + E – Cretaceous, Paleogene and Eocene carbonates, E – Eocene flysch. Bedding strike and dip / 1 K + Pc + E – kredni, paleocenski in eocenski karbonati, E – eocenski fliš. Vpad plasti 2 Paleogene reverse and thrust faults: BuF – reverse Buje Fault, BT – Buzet Thrust KT – Križ Thrust IT – Izola Thrust / paleogenski reverzni in narivni prelomi: BuF – Bujski reverzni prelom, BT – Buzetski narivni prelom, KT – Križni narivni prelom, IT – Izolski narivni prelom 3 Paleogene backthrust fault (Strunjan structure) / paleogenski povratni reverzni prelom (Strunjanska struktura) 4 Neogene-recent reverse fault / neogensko-recentni podrivni reverzni prelom 5 Istra-Friuli Thrust-Underthrust Zone / istrsko-furlanska narivno-podrivna cona 6 Larger sub-vertical fault with prevailing strike-slip component, extrusion boundary: proved ZaF – Zambratija Fault, inferred ZrF – Zrenj Fault / večji subvertikalni prelom s prevladujočo zmično komponento, meja iztiskanja: dokazano ZaF – Zambratijski prelom, domnevno ZrF – Zrenjski prelom 7 Right lateral strike-slip faults in the Črni Kal Anomaly zone, extrusion boundary: 3 – Gračišče series, 4 – Kastelec series / desnozmični prelomi v območju črnokalske anomalije, extrusion boundary: 3 – gračiški niz, 4 – kastelski niz 8 Right lateral offset in the Neogene to recent underthrust reverse fault, extrusion boundary / desnozmični premik v ploskvi neogenskega do recentnega podrivnega reverznega preloma, meja iztiskanja 9 Normal fault. Proved, inferred: RoF – Rokava Fault / normalni prelom. Ugotovljen, domneven: RoF – Rokavin prelom 10 Extensional crack (Gračišče) / ekstenzijska razpoka (Gračišče) 11 Neogene antiformal deformation of the Paleogene thrust plane: a – Glinščica/Rosandra, b – Varda, c – Črni Kal, d – Movraž, e – Perci village near Buzet / v neogenu antiformno deformirane paleogenske narivne ploskve: a – Glinščica, b – Varda, c – Črni Kal, d – Movraž, e – Perci pri Buzetu 12 Spatialy restricted folds : Strunjan structure, Tinjan structure or Tinjan Extrusion Wedge / gube prostorsko omejenega obsega: strunjan - ska struktura, tinjanska struktura ali tinjanski iztisni klin 13 Larger folds: SbA – Savudrija-Buzet Anticline, BaA – Bazovica Anticline, LiS – Lipica Syncline / večje gube: SbA – Savudrijsko-Buzetska antiklinala, BaA – Bazovska antiklinala, LiS – Lipiška sinklinala 14 Extrusion direction / smer iztiskanja 15 Extrusion evidence locations: 1 – Zambratija, 3 – Gračišče, 4 – Kastelec / mesta z dokazi iztiskanja: 1 – Zambratija, 3 – Gračišče, 4 – Kastelec 16 A saddle above Trieste between Mt. Mai/Maj and Mt. Mote Calvo/Globojnar at elevation point 416 m / sedlo nad Trstom med Majem (Mai) in Globojnarjem (Monte Calvo) na koti 416 m 19 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Rosand r a Glinščica Rižan a Dragonja Rokava Mirna SbA LiS BaA SbA TRIESTE TRST IZOLA ISOLA Tinjan Strunjan UMAG UMAGO BUJE BUZET G U L F O F T R I E S T E SECTION Fig. 8 SEC. a b 4 1 3 BT KT IT RoF ZrF ZaF BuF c d e a - e Slavnik 0 5 1 0 km A K+Pc+E E B 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 ZrF ZaF 1, 3, 4 20 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK wedge, as well as numerous valleys of streams that sink between the middle Dragonja and Bračana rivers in the limestone of the Savudrija-Buzet An - ticline. The middle Mirna also flows transversely across the wedge and the Savudrija-Buzet Anti - cline. Northwest of the Rokava Fault, transverse valleys no longer dominate: here the lower Drag - onja, Drnica, Badaševica, Rižana and Osapska reka rivers have deepened their beds along other struc- tural elements. Based on this, it appears that the north-western part of the wedge was extruded as a relatively homogeneous block. Now let’s take a look at the north-eastern bor - der of the North Istra Extrusion Wedge between the upper Mirna and lower Glinščica/Rosandra riv - ers. In order to understand the causes of the shear zone formation that runs obliquely in the direction of thrusting, or underthrusting, we need to take a closer look at the Istra-Friuli Thrust-Underthrust Zone structure. In the Čičarija , it consists of sev- eral similar structural duplexes. The anticlines in the fronts of duplexes are composed of Paleogene limestone followed by the transitional marl or by f lysch in some places. Each duplex is covered by the Pg limestone core of the next duplex of the same structure. The axes of the frontal limestone anti - clines regionally plunge towards the northwest, so that in the north-western part of the Istra-Friuli Thrust-Underthrust Zone, the Paleogene limestones are no longer at the surface, but the transitional marl or flysch of the upper duplexes is thrust on the transitional marl and flysch of the lower ones. The described conditions can be seen on the OGK (sheet Tr ie s t e), s i mpl i f ie d on t he t e c ton ic s k e tc h of nor t he r n Oglejmo si zdaj severovzhodno mejo sever - noistrskega iztisnega klina med zgornjo Mir - no in spodnjo Glinščico. Da bi razumeli vzroke nastanka zmične cone, ki poteka poševno na smer narivanja, oziroma podrivanja, si moramo podrobneje ogledati zgradbo istrsko-furlanske narivno-podrivne cone. Ta je na območju Čiča - rije sestavljena iz več podobnih narivnih lusk. V njenem jugovzhodnem delu ležijo v čelih lusk čel - ne antiklinale iz paleogenskega apnenca na kate- rem ležijo prehodni laporji in ponekod tudi fliš, ki ga prekriva paleogenski apnenec, ki gradi čelo naslednje luske enake zgradbe. Osi čelnih antik - linal iz apnenca regionalno tonejo proti severo- zahodu, tako da v severozahodnem delu istrsko - -furlanske narivno-podrivne cone paleogenski apnenci niso več na površju, temveč je prehodni lapor ali fliš zgornjih lusk narinjen na prehodni lapor in fliš spodnjih lusk. Opisane razmere so vidne na OGK (list Trst), poenostavljeno na tek - tonski skici severne Istre, kjer je fliš označen s sivim odtenkom (sl. 2 in 4A). Severozahodni boki karbonatnih antiklinal v čelih lusk se na površju izklinjajo v pasu med zgornjo Mirno in spodnjo Glinščico v smeri SSE-NNW, narivne ploskve pa potekajo naprej po flišu proti NW. Potek narivnic v flišu na sliki 4A ni izrisan, temveč le nakazan v bližini morske obale, kjer narivnice praviloma ležijo v dnu zalivov, kar pomeni, da so ti nastali po tektonsko prizadetih conah. Narivnice v fli - šu med obalo in zmično cono v smeri SSE-NNW niso izrisane zato, ker jih je potrebno detajlno geološko skartirati. Karbonatne antiklinale v če - lih lusk med zgornjo Mirno in spodnjo Glinščico Fig. 5. Structural peculiarities of Istra and Istra-Friuli Thrust-Underthrust Zone. Sl. 5. Strukturne posebnosti Istre in istrsko-furlanske narivno-podrivne cone. 1 Left-lateral strike-slip Zambratija Fault: sub-horizontal slickensides on the plane 30/90 (Fig. 2, location 1; Fig. 4A, location 1) / Zambrati - jski levozmični prelom: subhorizontalne drse v ploskvi 30/90 (sl. 2, točka 1; sl. 4A, točka 1) 2 Right-lateral strike-slip Kvarner Zone: right-lateral strike-slip along the plane 110/30, which was primarily parallel to the Dinarides. Above Flanona Hotel near Plomin (town) (Fig. 2, location 2) / kvarnerska desnozmična cona: desno zmikanje v ploskvi 110/30, ki je imela prvotno smer Dinaridov. Nad hotelom Flanona pri Plominu (sl. 2, točka 2) 3 Extensional crack in direction 340/50 at Gračišče (Fig. 4A, location 3) / ekstenzijska razpoka v smeri 340/50 pri Gračišču (sl 4A, točka 3) 4 Fault zone in flysch in direction 50/50 zone of Neogene-recent underthrust reverse faults above Gabrovica village (Fig. 4A, location »c«; Fig. 8, Istra-Friuli Thrust-Underthrust Zone) / prelomna cona v flišu v smeri 50/50 cona neogensko-recentnih podrivnih reverznih prelo - mov nad Gabrovico (sl. 4A, točka »c«; sl. 8, istrsko-furlanska narivno-podrivna cona) 5 Antiformally bent paleogene thrust plane in the Varda road cut (Fig. 4A, location »b«) / antiformno usločena paleogenska narivna ploskev v cestnem useku Varda (sl. 4A, točk »b« 6 Antiformally bent paleogene thrust plane above Movraž village (Fig. 4A, location »d«) / antiformno usločena paleogenska narivna ploskev nad Movražem (sl. 4A, točka »d«) 7 Fault zone in flysch in direction 25/45 Paleogene thrust with stepped oblique cut, Valmarin (Škofije). Structural type of disordered jump (Fig. 7D) / prelomna cona v flišu v smeri 25/45 cona paleogenskega nariva, ki ima stopničasti poševni rez, Valmarin (Škofije). Strukturni tip neurejenega preskoka (sl. 7D) 8 Backthrust in the Strunjan structure in direction 230/60 (Figs. 4A and 8) / povratni reverzni prelom v strunjanski strukturi v smeri 230/60 (sl. 4A in 8) 9 Transverse folding in the Tinjan Extensional Wedge. Axial planes in direction 310/90 .Construction cave for the water reservoir at Slatine village (Fig. 4A, location 4) / prečno gubanje v tinjanskem iztisnem klinu. Osna ravnina gub v smeri 310/90 Izkop za vodohran v Slatinah (sl. 4A, točka 4) 21 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria 1 2 3 5 6 7 8 9 M o v r a ž 4 22 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Istra, where the flysch is marked with a grey hatch (Figs. 2 and 4A). The north-western f lanks (if a sim - ple fold is determined e.g. by the northern and the southern limbs and an axial plane between them we are missing the term to describe the western and the eastern part of the fold. As there is no adequate term for these in the literature, a term flank is used here. Flank and limb should therefore not be in - terchangeable terms) of the carbonate anticlinesin the fronts of the duplexes pinch out on the surface in the SSE-NNW trending belt between the upper Mirna and the lower Glinščica/Rosandra, and the thrust planes continue in flysch towards the NW. The course of the thrusts in the flysch in Fig. 4A is not drawn, but only indicated near the sea coast, where thrust planes generally lie at the bottom of bays, which means that they were formed along tectonically affected zones. Thrusts in the flysch between the coast and the shear zone in the SSE- NNW direction are not fully drawn because they need to be geologically mapped in detail. The car - bonate anticlines in the fronts of the duplexes be - tween the upper Mirna and the lower Glinščica/ Rosandra lie in an echelon series, which in reality represents a wider zone and not just a single set of duplexes. The north-western edges of the echelon-ar - ranged frontal carbonate anticlines are accom - panied by the SSE-NNW trending subvertical right-lateral faults. These were mapped at the highway construction site in two areas (Placer, 2003; 2004): between the lower entrance to the Kastelec tunnel and the upper entrance to the Dekani tunnel (260/90, 250/90, 240/80) (Fig. 4A, point 4) and in the vicinity of Gračišče, where a fault (70/80) was measured, otherwise without visible slickensides, but in its western flank there are pronounced extensional fractures in the 350- 0/70 direction, which indicate extrusion towards the north-northwest (Fig. 4A, point 3; Fig. 5/3). These two groups are referred to as the Kastelec and Grači šče sets of right-lateral strike-slip faults throughout the article. To understand their mean - ing, let’s look at the structural analysis of the re - lationship between these faults and the thrust duplexes of the Istra-Friuli Thrust-Underthrust Zone, with frontal anticlines composed of Paleo - gene limestone and Eocene flysch in the Figure 6. In the analysis, we proceed from the idealized ech - elon arrangement of duplexes and frontal anticlines (Fig. 6A), where in the ground plane the edges of the Paleogene limestone anticlines are connected to form an envelope »e«, which runs in a 340° di - rection. This direction was chosen because it il - lustrates the location of the right-lateral strike-slip ležijo torej v ešalonskem nizu, ki pa ni linearen, oziroma ne obsega le enega niza lusk, temveč za - jema širšo cono. Severozahodne robove ešalonsko razpore- jenih čelnih karbonatnih antiklinal spremljajo subvertikalni desnozmični prelomi v smeri SSE -NNW. Ti so bili na delovišču avtoceste kartira - ni na dveh območjih (Placer, 2003; 2004); med spodnjim vhodom v predor Kastelec in zgornjim vhodom v predor Dekani 260/90, 250/90, 240/80 (sl. 4A, točka 4) in v okolici Gračišča, kjer je bil izmerjen prelom 70/80, sicer brez vidnih drs, toda v njegovem zahodnem krilu nastopajo iz - razite ekstenzijske razpoke v smeri 350-0/70, ki kažejo na iztiskanje proti severo-severozahodu (sl. 4A, točka 3; sl. 5/3). V nadaljevanju članka ti dve skupini imenujemo kastelski in gračiški niz desnozmičnih prelomov. Da bi razumeli njihov pomen, si na sliki 6 oglejmo strukturno analizo odnosa med temi prelomi in narivnimi luska - mi istrsko-furlanske narivno-podrivne cone v čelu katerih ležijo antiklinale iz paleogenskega apnenca in eocenskega fliša. V analizi izhajamo iz idealizirane ešalonske razporeditve lusk in čelnih antiklinal (sl. 6A), kjer so v tlorisni ravni - nin robovi antiklinal iz paleogenskega apnenca povezati z ovojnico ali envelopo »e«, ki poteka v smeri 340°. Ta smer je bila izbrana zato, ker ponazarja lego desnozmičnih prelomov kastel - skega in gračiškega niza. Ovojnica ali envelo - pna »e« leži v ravnini, ki jo imenujemo ovojna ali envelopna ravnina »E«. Da bi ugotovili njen vpad je bila iz terenskih podatkov določena sre - dnja lega paleogenskih narivnih ploskev »P«, ki znaša 50/30 in srednja lega plasti »D« v krilu čelne antiklinale, ki znaša 35/20. Konstruirana presečnica »s« na sliki 6B ima smer 341/11, zao - kroženo 340/10, kar je enako smeri envelope »e« na sl. 6A. To pomeni, da ležita ovojnica »e« in presečnica »s« v ovojni ravnini »E«, ki ima smer 340 ° in vpad 90 °. V našem primeru je ovojna ravnina »E« konstruirana meja med območjem, kjer v luskah prevladuje paleogenski apnenc in območjem, ki je zgrajeno iz mehkejšega fliša, zato predstavlja labilno cono po kateri bi lahko nastal zmični prelom. Konstrukcija na sliki 6 je idealizirana, ven - dar dobro ponazarja razmere v pasu med zgor - njo Mirno in spodnjo Glinščico. Ovojna ravnina »E« ponazarja vzroke za nastanek kastelskega in gračiškega niza subvertikalnih desnozmič - nih prelomov v smeri SSE-NNW, le da v naravi ne gre za eno ovojno ravnino ali zmični prelom, temveč za cono, ki je sestavljena iz več podob - nih ešalonskih segmentov. Izločena sta kastelski 23 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Flysch Limestone (D) (P) D P s D P s faults of the Kastelec and Grači šče series. The en - velope »e« lies in a plane called the envelope plane »E«. In order to determine its elements (azimuth and dip), the middle position of Paleogene thrust surfaces »P« was determined from the field data, which is 50/30, and the middle position of layer »D« in the limb of the frontal anticline, which is 35/20. Constructed intersection »s« in Figure 6B has a bearing of 341/11 rounded to 340/10, which is parallel to the direction of envelope »e« in Fig - ure 6A. This means that envelope »e« and the in - tersection »s« lie in the envelope plane »E«, which has a 340° bearing and vertical dip. In our case, the enveloping plane »E« is a constructed bound - ary between an area dominated by duplexes of Pa - leogene limestone and an area built of softer (less rigid) flysch, so it represents a labile zone along which a strike-slip fault could occur. The construction in Figure 6 is idealized, but it well illustrates the conditions in the belt between the upper Mirna and lower Glinščica/Rosandra rivers. The enveloping plane »E« illustrates the causes of the formation of the SSE–NNW trend - ing Kastelec and Gračišče series of subvertical right-lateral strike-slip faults, except that in-situ it is not a single enveloping plane or strike-slip fault, but a zone consisting of several similar echelon segments. Kastelec and Gračišče series are oblite - rated here because they are emphasized in the Fig - ure 4A due to their importance. Echelon-arranged carbonate anticlines, as pre- sented in Figue 6A, represent a stack of competent blocks in a less competent medium, therefore we propose introducing the name stacked structure, and envelope fault for the fault that occurred along the envelope plane of the stacked structure. The complex dextral strike-slip zone between the upper Mirna and the lower Glinščica/Rosan - dra, which is characterized by a stacked struc- ture and enveloping faults, is called the Črni Kal Anomaly. The regional cause of its formation is explained in the chapter on the formation of the North Istra Extrusion Wedge and the South Istra Pushed Wedge. In addition to the Paleogene thrust faults, re- verse faults (Figs. 4A and 5/4) also occur in the Istra-Friuli Thrust-Underthrust Zone, represent - ing the leading structures of the Kraški rob (geo - graphic region along the SW margin of the Čičarija plateau between the villages of Socerb and Mlini Fig. 11) recent uplift. Next to them, the Paleogene thrusts planes are anticlinally bent (Fig. 5/5). In Fig. 4A, some examples of such deformation are marked with the letters »a« (Glinščica/Rosandra), »b« (Varda, Fig. 5/5), »c« ( Črni Kal), »d« (Movraž, Fig. 6. Formation of Kastelec and Gračišče series of faults. Sl. 6. Nastanek prelomov kastelskega in gračiškega niza. A. Stacked structure: ideal echelon arrangement of Paleogene lime - stone and flysch duplexes. The north-western edges of the thrusted frontal anticlines of Pale - ogene limestone form an echelon series whose »e« envelope is straight and runs due NNW (340°), which is oblique to the trust planes running NW (50°). / Zložbena zgradba: idealni ešalonski niz narivnih lusk iz paleogenskega apnenca in fliša. Severozahodni robovi čelnih antiklinal iz paleogenskega apnenca tvorijo ešalonski niz, katerega ovojnica »e« ali envelopa je ravna in poteka v smeri NNW (340°), kar je poševno na narivne ploskve lusk, ki potekajo v smeri NW (50°). B. Construction of the intersection between the middle position of the thrust surfaces of the scales (»P« = 50/30) and the middle position of the bedding (»D« = 35/20). The intersection »s« lies in the direction 341/11, rounded 340/10, with its direction iden - tical to the direction of the envelope »e«, which means that both lines lie in a single plane. It is vertical and called the enveloping plane »E«, which lies in the direction 70/90, (or 250/90). / Kon- strukcija presečnice med srednjo lego narivnih ploskev lusk (»P« = 50/30) in srednjo lego plasti (»D« = 35/20). Presečnica »s« leži v smeri 341/11, zaokroženo 340/10, njena smer je identična s smerjo ovojnice ali envelope »e«, kar pomeni, da ležita obe premici v eni ravnini. Ta je vertikalna. Imenujemo jo ovojna ali envelopna ravnina »E«, ki leži v smeri 70/90, oziroma 250/90. 24 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Fig. 5/6) and »e« (Perci near Buzet). Some of these Paleogene thrust surfaces show a certain degree of metamorphosis (verbally communicated by Dr. Bogomir Celarc, 2021), which, in addition to be - ing folded, undoubtedly indicates their inactivity and that the reverse faults are younger, i.e. of Neo - gene-recent age. Unlike the others, they are called underthrust reverse faults. The antiformly bent thrust surface in Glinščica/Rosandra a, marked with »a«, is probably related to the Bazovica An - ticline. In the area of the Črni Kal Anomaly , there are SSE–NNW trending (Kastelec and Gračišče se - ries) subvertical right-lateral strike-slip faults and SE-NW trending reverse underthrust faults. The relationship between them is multi-phased, in some places the first intersect the others, in oth - ers it is the other way around. In the zones char - acterised by reverse underthrust faults, signs of sub-horizontal extrusion towards the northwest to north-northwest are also found in the area of the Črni Kal Anomaly. Based on the geometrical conditions on the tip of the North Istra Extrusion Wedge, we conclude that there exists an underthrusting reverse fault between Gračišče and Buzet, which is occasionally active also as a right-lateral strike-slip. The un - derthrusting kinematics next to it is indicated by the anticlinal folding »e«, while the extrusion is indicated by the transverse valleys parallel to the Rokava Fault (Fig. 4B). The Rokava Fault also ter - minates next to this underthrusting fault (Fig. 4A, point 3), due to which the Rokava valley suddenly turns to the southeast, and the Buzet Thrust also leans on it. We assume that the oscillation between subho - rizontal dextral strike-slip and underthrusting is a characteristic of the Istrian Pushed Area. With this mechanism and intermediate variants, we can explain large tectonic mirrors in the Raša fault zone mentioned in the chapter on the Raša fault in this article. The discovery of the underthrust reverse faults requires a new geological mapping of the Istra-Fri - uli Thrust-Underthrust Zone, especially the part that takes place in flysch. The sketch of its already published (thrust) structure (Placer et al., 2004, Fig. 1; 2010, Fig. 5; Placer, 2005, Fig. 1; 2007, Fig. 2), is based on knowledge of the Buzet Thrust, ex - amined from Buzet to the Gulf of Trieste coast and takes place exclusively in flysch layers (Placer et al., 2004). The Buzet Thrust Thrust plane on the surface obliquely intersects the strata everywhere at an angle of around 30°, and beds are folded into a flanking fold along the thrust plane, thus we in gračiški niz, ki sta zaradi svojega pomena po - udarjena na sliki 4A. Ešalonsko razporejene karbonatne antikli- nale, kot je to predstavljeno na sliki 6A, pred - stavljajo skladovnico ali zložbo kompetentnih blokov v manj kompetentnem mediju, zato predlagamo, da se uvede naziv zložbena zgradba ali zložbena struktura, za prelom ki je nastal po ovojni ravnini zložbene strukture pa ovojni ali envelopni prelom. Izraz zložbena zgradba izva - jamo iz skladovnice drv, ki so zložena v zložbo, izraz skladovna zgradba bi bil neprimeren, ker se prekriva s skladi, oziroma plastmi. Kompleksno desnozmično cono med zgornjo Mirno in spodnjo Glinščico, za katero je značil - na zložbena zgradba in ovojni prelomi, imenu - jemo črnokalska anomalija. Regionalni vzrok za njen nastanek bo razložen v poglavju o na - stanku severnoistrskega iztisnega in južnoistr - skega potisnega klina. Poleg paleogenskih na - rivnih prelomov nastopajo v istrsko-furlanski narivno-podrivni coni tudi reverzni prelomi (sl. 4A in 5/4), ki predstavljajo vodilne struktu - re recentnega dviganja kraškega roba. Ob njih so ploskve paleogenskih narivov antiklinalno usločene (sl. 5/5). Na sliki 4A so nekateri pri - meri takih usločitev označeni z malimi črkami »a« (Glinščica), »b« (Varda, sl. 5/5), »c« (Črni Kal), »d« (Movraž, sl. 5/6) in »e« (Perci pri Bu - zetu). Nekatere paleogenske narivne ploskve od teh kažejo določeno stopnjo metamorfoze (ustno posredoval dr. Bogomir Celarc 2021), kar poleg tega, da so nagubane, nedvomno kaže na njiho - vo neaktivnost in da so reverzni prelomi mlaj - ši, torej neogensko-recentne starosti. Za razli - ko od drugih jih imenujemo podrivni reverzni prelomi. Antiformna usločitev narivne ploskve v Glinščici, ki je označena z »a« je verjetno po - vezana z Bazovsko antiklinalo (Bazovica, ba - zovski: Merku, 2006, 42). V območju črnokalske anomalije torej nasto - pajo subvertikalni desnozmični prelomi smeri SSE-NNW (kastelski in gračiški niz) in pod - rivni reverznimi prelomi smeri SE-NW. Odnos med njimi je večfazen, ponekod prvi sekajo dru - ge, ponekod je obratno. V conah podrivnih re - verznih prelomov najdemo v območju črnokalske anomalije tudi znake subhorizontalnega iztiska - nja proti severozahodu do severo-severozahodu. Po geometrijskih razmerah na območju ko - nice severnoistrskega iztisnega klina sklepamo, da obstoja med Gračiščem in Buzetom podriv - ni reverzni prelom, ki je postal občasno tudi desnozmičen. Na podrivno kinematiko ob njem kaže antiklinalna usločitev »e«, na iztiskanje 25 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria DUPLEX PRESSURE POCKET A B C D PRESSURE POCKET kažejo prečne doline potokov, ki so vzporedne Rokavinemu prelomu (sl. 4B). Ob njem se izkli - nja tudi Rokavin prelom (sl. 4A, točka 3), zaradi česar dolina Rokave nenadoma zavije proti jugo - vzhodu. Nanj se naslanja tudi Buzetski narivni prelom. Domnevamo, da je nihanje med subho - rizintalnim desnim zmikanjem in podrivanjem značilnost istrskega potisnega območja, s tem mehanizmom in vmesnimi variantami lahko razložimo velika tektonska zrcala v prelomni coni Raškega preloma, ki jih v tem članku ome - njamo v poglavju o Raškem prelomu. Odkritje podrivnih reverznih prelomov terja ponovno geološko kartiranje istrsko-furlanske narivno-podrivne cone. Zlasti tistega dela, ki poteka v flišu. Skica njene narivne zgradbe, ki je bila doslej večkrat objavljena (Placer et al., 2004, sl. 1; 2010, sl. 5; Placer, 2005, sl. 1; 2007, sl. 2) je izhajala iz poznavanja Buzetskega narivnega preloma, ki je bil pregledan od Buzeta do obale Tržaškega zaliva in poteka izključno v flišnih pla - steh (Placer et al., 2004). Njegova narivna plo - skev na površju povsod poševno seka plasti pod kotom okoli 30°, ob njej so plasti večinoma po - vite v obnarivno gubo, zato sklepamo, da je tako tudi v globini, na sliki 7 ga predstavljamo kot primer premega poševnega reza. Ostale narivne prelome v flišu znotraj istrsko-furlanske nariv - no-podrivne cone, smo doslej interpretirali v skladu z zgradbo Buzetskega narivnega preloma. Pri poznejših detajlnih raziskavah tega ozemlja pa se je pokazalo, da poševni rez v flišu ni ved- no raven, zelo pogosto je stopničast (sl. 7B), kar pomeni, da poteka narivna ploskev nekaj časa med plastmi, nekaj časa poševno nanje. V takem primeru je vpad narivne ploskve nekoliko bolj strm. Ko poteka med plastmi, nastopajo ob njej identične vzporedne medplastne deformacije, ponekod pa se razvijejo dupleksi. Pri preskoku iz enega nivoja plasti v drugega se pojavljata dva tipa zgradbe prelomne cone. V prvem primeru so se plasti zasukale v obprelomno gubo (sl. 7C), v drugem se razvije neurejeno zaporedje sko - raj izoklinalnih gub in reverznih prelomov (sl. 7D in 5/7). Struktura drugega ali neurejenega tipa preskoka je na moč podobna novonastalim conam podrivnih reverznih prelomov (sl. 5/4). Pomemben kriterij razlikovanja so strukturni žepi, ki se nahajajo v čelih narivnih struktur ne - urejenega tipa (sl. 7D) in dupleksov (sl. 7B). V njih običajno nastopajo močno stlačene pretrte kamnine ali zgoščine, ki imajo glede na okoliški pretrti medij povečano volumsko gostoto. Obrav - navane žepe imenujemo tlačni strukturni žepi, skrajšano tlačni žepi, ki predstavljajo novost v conclude that it is the same in depth. An example of an oblique cut is presented in Figure 7A. Oth - er thrust faults in the flysch within the Istra-Friuli Thrust-Underthrust Zone have so far been inter - preted in accordance with the structure of the Buzet Thrust. During later detailed research of this area, it was shown that the oblique cut in the flysch is not always straight, but is often stepped (Fig. 7B), which means that the thrust plane sometimes runs between the layers, and sometimes obliquely to them. The thrust plane dip in such a case is some - what steeper. When it passes between layers, iden - tical parallel interlayer deformations appear next to it, and locally duplexes may evolve, and when they Fig. 7. The course of the thrust plane in flysch layers. Profile. A. Straight oblique cut. B. Stepped oblique cut. C. Jump with natural folds. D. Disordered jump (Fig. 5/7). Sl. 7. Potek narivne ploskve v flišnih plasteh. Profil. A. Premi poševni rez. B. Stopničasti poševni rez. C. Preskok z obnarivnimi gubami. D. Neurejeni preskok (sl. 5/7). 26 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK jump from one level to another, two types of frac - ture zone structure appear. In the first case, the lay - ers are twisted into a fold along the fault (Fig. 7C), in the second a disordered sequence of almost iso - clinal folds and reverse faults develops (Figs. 7D and 5/7). The structure of the second or disordered type of jump is very similar to newly formed zones of underthrust reverse faults (Fig. 5/4). An important distinguishing criterion is the structural pockets located in the faces of thrust structures of disordered type (Fig. 7D) and du - plexes (Fig. 7B). They usually contain highly compressed crushed rocks or clusters, which are denser compared to the surrounding crushed (but not compressed as in the pressure pocket) medi - um. Said pockets are structural pressure pockets, abbreviated as pressure pockets representing a novelty in the case of the thrust duplexes of the described type. Pressure pockets of this type were observed in thrust zones, while other zones of un- derthrust reverse faults have not been explored in this sense. However, they do not form in duplexes, which accompany the phenomena of underwater synsedimentary gravitational sliding. An excep - tional example of the latter can be seen in the fly - sch cliff of Simonov zaliv (Simon bay) near Izola, which does not feature a pressure pocket at the head of the landslide, but a relaxed intertwining of layers that were only partially lithified at the time of sliding along the inclined seabed. Due to the importance of this phenomena, the structure is named the Kane landslide after the nearby ham - let and cape. In the Summaries and Excursions for the 4th Slovenian Geological Congress in Ankaran in 2014, the mentioned landslide was shown as an example of a thrust duplex structure (Vrabec & Rožič, 2014, 84-91). The task of re-mapping is to take into account all these peculiarities; above all it is necessary to dis - tinguish the zones of disordered jump of step thrust surfaces (Figs. 7B and 5/7) from the Neogene-re - cent zones of reverse thrust faults (Fig. 5/4). The structural relationships in the North Istra Extrusion Wedge are sketched in profile in Fig - ure 8. The Paleogene thrusts (Buzet Thrust, Izola Thrust, Križ Thrust, antiformally folded thrusts of the Kraški rob) and the reverse Buje Fault with its backthrusts. The left-lateral strike-slip Zambratija Fault, enveloping or envelope right-lateral strike- slip faults of the Črn i Kal Anomaly, and underthrust reverse faults are also of Neogene-recent age. Underthrusting occurs only in the north-east- ern part of the profile along the underthrust re- verse faults, where their hanging blocks are being uplifted. This is geomorphologically manifested primeru narivnih dupleksov opisanega tipa. Tlačne žepe tega tipa smo opazovali v narivnih conah, medtem ko so ostale cone podrivnih re - verznih prelomov v tem smislu neraziskane. Ne nastajajo pa v dupleksih, ki spremljajo pojave podvodnega singenega gravitacijskega drsenja, izjemen primer slednjega je viden v f lišnem klifu Simonovega zaliva v Izoli, kjer se v čelu plazu ne nahaja tlačni žep temveč sproščeni preplet plasti, ki so bile v času polzenja po nagnjenem morskem dnu le delno strjene. Predlagamo, da ta primer poimenujemo po bližnjem zaselku in rtiču plaz Kane. V Povzetkih in ekskurzijah za 4. slovenski geološki kongres v Ankaranu leta 2014, je bil omenjeni plaz prikazan kot primer strukture narivnega dupleksa (Vrabec & Rožič, 2014, 84–91). Naloga ponovnega kartiranja je upoštevati vse te posebnosti, predvsem je potrebno ločiti cone neurejenega preskoka stopničastih nariv - nih ploskev (sl. 7E in 5/7) od con neogensko-re - centnih podrivnih reverznih prelomov (sl. 5/4). Strukturni odnosi v severnoistrskem izti - snem klinu so skicirani v profilu na sliki 8. Pa - leogenske starosti so narivi (Buzetski, Izolski, Križni nariv, antiformno usločeni narivi Kraške - ga roba) in Bujski reverzni prelom s povratnimi narivi. Neogensko-recentne starosti so Zambra - tijski levozmični prelom, desnozmični ovojni ali envelopni prelomi črnokalske anomalije in pod - rivni reverzni prelomi. Podrivanje se dogaja le v severovzhodnem delu profila ob podrivnih reverznih prelomih, ob katerih se dvigujejo njihove krovninske grude. To se geomorfološko kaže kot dviganje Kraškega roba, kar je povzročilo antiformni upogib pale - ogenskih narivnih ploskev. Aktualno dviganje kraškega roba dokazuje kontrolni izračun nivel - manskega vlaka preko Kraškega roba (Rižnar et al., 2007). V profilu na sliki 8 je shematsko prikazana tudi lega desnozmičnih ovojnih prelomov. Njihov odnos do podrivnih reverznih prelomov je am - bivalenten, prva opažanja so pokazala, da pre - vladujejo podrivne strukture z drsami po vpadu, vendar najdemo znake desnega zmikanja tudi v conah podrivnih reverznih prelomov. Domneva - mo, da je v začetni fazi razvoja severnoistrskega iztisnega klina prevladovalo iztiskanje, pozneje podrivanje, verjetno pa se občasno še vedno po - javlja tudi iztiskanje. V jugozahodnem delu profila pri kartiranju površja nismo našli neogensko-recentnih pod - rivnih struktur. V tem primeru je zanimiva primerjava seizmičnega profila morskega dna 27 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria NORTH ISTRA EXTRUSION WEDGE ENVELOPE FAULT ČRNI KAL ANOMALY C Fig. 5/8 NOT TO SCALE Fig. 8. Sketch of the cross-section of the North Istra Extrusion Wedge. The course of the profile in Fig. 4A. Adapted after Placer et al. (2010, Fig. 6). Sl. 8. Skica prečnega profila severnoistrskega iztisnega klina. Potek profila na sl. 4A. Dopolnjeno po Placer et al. (2010, sl. 6). 1 K + Pc + E – Cretaceous, Paleocene and Eocene carbonates, E – Eocene flysch / K + Pc + E – kredni, paleocenski in eocenski karbonati, E – eocenski fliš 2 Paleogene reverse and thrust fault: reverse Buje Fault, Izola Thrust, Križ Thrust, Buzet Thrust / paleogenski reverzni in narivni prelom: Bujski reverzni prelom, Izolski narivni prelom, Križni narivni prelom, Buzetski narivni prelom 3 Paleogene backthrust fault / paleogenski povratni reverzni prelom 4 Neogene-recent underthrust reverse fault / neogensko-recentni podrivni reverzni prelom 5 Left strike-slip Zambratija Zone, a set of right strike-slip faults of the Črni Kal Anomaly (envelope faults) / zambratijska levozmična cona, niz desnozmičnih prelomov črnokalske anomalije (ovojni ali envelopni prelomi) 6 Area of interlayer movements in the Strunjan structure (Placer et al., 2010, Figs. 18 and 19) / območje medplastnih premikov v strunjanski strukturi (Placer et al., 2010, sl. 18 in 19) 7 Mirror folded area in the Strunjan structure / zrcalno nagubano območje v strunjanski strukturi 8 Direction of the Neogene-recent movement of the Istra block / smer neogensko-recentnega pomikanja istrskega bloka 9 Recent uplift of the Kraški rob / recentno dviganje kraškega roba 10 Sketch of the envelope faults position within the Črni Kal Anomaly / skica lege ovojnih (envelopnih) prelomov znotraj črnokalske anom - alije as the uplift of the Kraški rob, which caused the antiform bending of the Paleogene thrust surfaces. The current uplift of the Kraški rob is evidenced by the recalculation of the levelling lines across the Kraški rob (Rižnar et al., 2007). The position of the right-lateral strike-slip en - velope faults is schematically presented in pro - file in Figure 8. Their relationship to underthrust reverse faults is ambivalent: first observations showed that underthrust structures with slicken- sides along (parallel to) the bedding predominate, but evidence of dextral slip are also observed in underthrust reverse fault zones. It is assumed that extrusion was dominant in the initial phase of the North Istra Extrusion Wedge development, fol - lowed by underthrusting, but extrusion probably still occurs from time to time. prečno na Izolsko antiklinalo (Busetti et al., 2013, sl. 3) z odsekom profila na sliki 8 med Sa - vudrijsko-Buzetsko in Izolsko antiklinalo. Kar - tiranje je pokazalo, da sta poleg Izolske antik- linale vidna še medplastni nariv v prehodnem laporju antiklinale, ki smo ga poimenovali Izol - ski nariv in Križni nariv za katerega na kopnem ni bilo mogoče ugotoviti v kakšnem struktur - nem odnosu je z Izolsko antiklinalo. Med Sa - vudrijsko-Buzetsko antiklinalo in Križnim na - rivom ležijo povratni narivi, ki so spremljajoča struktura Bujskega reverznega preloma. V bloku med povratnimi narivi in Križnim narivom je fliš zrcalno simetrično naguban. V seizmičnem profilu se Izolska antiklinala nagiba proti jugo- zahodu, kar kaže na paleogensko čelno narivno gubo, ki je najbližja Križnemu narivu. Vendar ta 28 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK In the south-western part of the profile, no Neo- gene-recent underthrust structures were found during surface mapping. In this case a comparison of the seismic profile of the seabed transverse to the Izola Anticline (Busetti et al., 2013, Fig. 3) with the section of the profile in Figure 8 between the Savudrija-Buzet and Izola Anticlines is interesting. G e olog ic a l m appi ng showe d t h at t her e a r e a l s o i nter - layer thrusts (the Izola, and the Cross Thrusts) vis - ible in the transitional marl, in the Izola Anticline. It was not yet possible to determine their structural relationship with the Izola Anticline. Backthrusts and related structures between the Savudrija-Buzet Anticline and the Križ Thrust belong to the reverse Buje Fault. The flysch is mirror-symmetrically fold - ed in the structural block between the backthrusts and the Križ Thrust. The Izola Anticline is tilted to the southwest in the seismic profile, indicating a Paleogene frontal thrust fold, which is closest to the Križ Thrust. The thrust fault is not visible in the seismic profile, so we assume that only a fold has de - veloped there, which has not yet been broken by the thrust plane. Post-Paleogene reactivation is men - tioned in the description of the seismic profile that only affected subvertical faults without significant impact on the structure. A fold in the flysch along the reverse underthrust indicates the symmetry of fold vergence in the Strunjan structure between the reverse thrusts and the Križ Thrust and is pre - sented in Figure 5/8. This was formed successively: first, folds formed in the Križ Thrust footwall, then along backthrusts. Justification of the sequence of events is given in the chapter on the formation of the North Istra Extrusion Wedge and the South Is - tra Pushed Wedge. The Kane landslide in Simonov zaliv lies in the area of the Strunjan structure, but, as we have already mentioned, it is not a tectonic formation in origin, but rather a synsedimentary phenomenon in the flysch. The landslide slid in a direction of roughly 310°, while signs of Paleogene thrusting show a direction of some 220°. The important question – the amount of dis - placement along the Paleogene thrusts, which rep - resent the boundary of the Dinaric thrust struc- ture – remains unanswered. While it could be relatively large, the debates regarding the struc- ture of the Dinarides have failed to produce an ac- ceptable solution. Interpretation of the profile in Figure 8 rep - resents some progress in understanding the mech - anism of movement of the Microadria towards the External Dinarides, which includes thrusting and underthrusting. The progress is obvious after comparison with the Umag - Kozina profile (Placer et al., 2010, fig. 6), where the underthrusting was v seizmičnem profilu ni viden, zato domneva - mo, da se je na območju geofizikalnega profila razvila le guba, ki je narivna ploskev še ni pre- trgala. V opisu seizmičnega profila je omenje - na popaleogenska reaktivacija, ki pa je zajela le subvertikalne prelome brez pomembnega vpli - va na zgradbo. Na sliki 5/8 je prikazana guba v flišu ob povratnem narivu, ki kaže na sime - trijo vergence gub v strunjanski strukturi med povratnimi narivi in Križnim narivom. Ta je nastala zaporedoma, najprej so se razvile gube v talnini Križnega nariva, nato ob povratnih nari - vih. Utemeljitev zaporedja dogodkov je podana v poglavju o nastanku severnoistrskega iztisnega in južnoistrskega potisnega klina. Plaz Kane v Simonovem zalivu leži v območju strunjanske strukture, vendar, kot smo že omenili, po izvoru ni tektonska tvorba, temveč je sinsedimentarni pojav v flišu. Plaz je drsel v smeri okoli 310°, medtem ko kažejo znaki paleogenskega nariva - nja na smer okoli 220°. Odprto ostaja vprašanje dolžine premika ob paleogenskih narivih, ki predstavljajo mejo di - narske narivne zgradbe. Ta bi bil lahko soraz - merno velik, vendar nam dosedanje razprave o zgradbi Dinaridov o tem še ne dajejo sprejemlji - vega odgovora. Interpretacija profila na sliki 8 pomeni na - predek pri razumevanju mehanizma premikanja Mikroadrije proti Zunanjim Dinaridom, ki zaje - ma potiskanje in podrivanje. Napredek je viden po primerjavi s profilom Umag - Kozina iz leta 2010 (Placer et al., 2010, sl. 6), ko se je podri - vanje obravnavalo kot reaktivacija paleogenskih narivnih ploskev v nasprotni smeri. Antikli - nalno usločene paleogenske narivne ploskve ob podrivnih reverznih prelomih, ki so na sliki 4A označene z »a«, »b«, »c«, »d« in »e«, nastopa - jo tudi v jugovzhodnem delu istrsko-furlanske narivno-podrivne cone, npr. nad Brestom pod najvišjim vrhom Čičarije, Velikim Planikom (1272 m). V tem smislu predstavlja strukturni izziv tudi zgradba Učke, zato je potrebno ponov - no strukturno obdelati celotno narivno-podriv- no cono med Tržaškim in Reškim zalivom. Narivi in prelomi znotraj severnoistrskega iztisnega klina se nadaljujejo proti severozaho- du. Iz strukturne rekonstrukcije podmorja Trža - škega zaliva (Carulli, 2011, sl. 3) in geofizikal - nega profila v smeri SW-NE (Busetti et al., 2012, sl. 2) je moč sklepati, da se zahodno od Savudrije os Savudrijsko-Buzetske antiklinale obrne proti severozahodu (sl. 2). O Zambratijskem prelomu ni podatkov, domnevamo pa, da spremlja Savu - drijsko-Buzetsko antiklinalo v podmorju Bujski 29 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria considered as a reactivation of Paleogene thrust planes in the opposite direction. Anticlinally de - formed Paleogene thrust planes next to under - thrust reverse faults, shown in Figure 4A, marked with »a«, »b«, »c«, »d« and »e«, also occur in the south-eastern part of the Istra-Friuli Thrust-Un - derthrust Zone, e.g. above Brest under Mt. Veliki Planik (1272 m), the highest peak of Čičarija . In this sense, Mt. Učka also represents a structural challenge, so it is necessary to structurally remap the entire thrust-underthrust zone between the Gulf of Trieste and the Gulf of Rijeka. Thrusts and faults within the North Istra Ex - trusion Wedge continue to the northwest. From the structural reconstruction of the Gulf of Trieste sea - bed (Carulli, 2011, fig. 3) and the geophysical profile in the SW-NE direction (Busetti et al., 2012, fig. 2), it can be concluded that the axis of the Savudrija-Buzet Anticline west of Savudrija turns to the northwest (Fig. 2). There is no information about the Zambrati - ja Fault, but we assume that the reverse Buje Fault follows the Savudrija-Buzet Anticline, and Carulli (ib.) also assumed the same. The change of direc - tion occurs also on the opposite side of the extru - sion wedge. Here the SSE-NNW trending Črni Kal Anomaly (the complex shear zone between the upper Mirna and lower Glinščica/Rosandra rivers), turns due SE-NW. The Bazovica Anticline and the Lipica Syncline north-northwest of the lower Glinščica/ Rosandra (Fig. 4A) have the same direction, so we believe that they probably represent the extreme structural limit of the Črn i Kal Anomaly. This is also indicated by the change in the Kraški rob trend on the saddle between Mt. Mai /Maj (~ 443 m) and Mt. Monte Calvo/Globojnar (~ 442 m) above Trieste, where the Kraški rob turns from the SSE-NNW to the SE-NW direction (Fig. 4). Despite the apparent - ly well-defined boundary on the mentioned saddle (elevation 416 m), it is quite clear that it is correct to speak only of the belt between the upper Mirna and the lower Glinščica/Rosandra, since the Črni Kal Anomaly cannot be strictly bounded. The North-Istra Extrusion Wedge thus transits into a parallelepiped roughly between Savudri- ja and Trieste, which is called the Trieste paral - lelepiped block or the Trieste parallelepiped. It is clear that due to the parallelopiped shape, the ef- fect of extrusion is completely absent, therefore the space between Savudrija and Trieste is also the north-western limit of the extrusion wedge (Fig. 2). The Trieste parallelepiped (A3) formally lies in the extension of the North Istra Extrusion Wedge (Ad2) and represents its south-eastern margin extrusion boundary, so it makes sense to use the term only in the discussion of block dynamics. reverzni prelom. Podobno je domneval tudi Ca - rulli (ib.). Sprememba smeri se dogodi tudi na nasprotni strani iztisnega klina, tu se črnolak - ska anomalija, oziroma kompleksna strižna cona med zgornjo Mirno in spodnjo Glinščico v smeri SSE-NNW, obrne v smer SE-NW. Severo-seve - rozahodno od spodnje Glinščice se nahajata Ba - zovska antiklinala in Lipiška sinklinala (sl. 4A), ki imata enako smer, zato menimo, da verjetno predstavljata skrajno strukturno mejo črnokal - ske anomalije. Na to kaže tudi sprememba smeri Kraškega roba na sedlu med Majem (Mai, oko - li 443 m) in Globojnarjem (Monte Calvo, okoli 442 m) nad Trstom, kjer se kraški rob iz smeri SSE-NNW obrne v smer SE-NW. Kljub na vi - dez dokaj natančno določeni meji na omenjenem sedlu (kota 416 m), pa je povsem jasno, da je korektno govoriti le o pasu med zgornjo Mirno in spodnjo Glinščico, saj črnokalske anomalije ni mogoče ostro omejiti. Severnoistrski iztisni klin preide torej prib- ližno med Savudrijo in Trstom v paralelepiped, ki ga imenujemo tržaški paralelepipedni blok ali tržaški paralelepiped. Jasno je, da je zaradi paralelepipedne oblike povsem izostal učinek iztiskanja, zato je prostor med Savudrijo in Tr - stom hkrati tudi severozahodna meja iztisnega klina (sl. 2). Tržaški paralelepiped (A 3 ) leži for - malno v podaljšku severnoistrskega iztisnega klina (Ad 2 ), vendar predstavlja njegovo jugo - vzhodno stranico meja iztiskanja, zato je termin smiselno uporabljati le v diskusiji o dinamiki blokov. Glede na dinamiko severnoistrskega iztisne - ga klina bi bilo povsem mogoče, da bi zaradi ekstenzije v jugovzhodni polovici klina in bloka- de nasproti tržaškemu paralelepipedu, prišlo v severozahodni polovici iztisnega klina do guba- nja prečno na iztiskanje, podobno kot v tinjan - skem iztisnem klinu (Placer, 2005, sl. 3), kjer so te gube lepo razvite (sl. 4A in 5/9). Tinjanski iztisni klin je miniaturni pendant severnoistr - skega iztisnega klina, zato bi tudi pri slednjem pričakovali med Rokavinim prelomom in jugo - vzhodno mejo tržaškega paralelepipeda več gub, ali pa vsaj eno veliko. Pri kartiranju površja teh nismo odkrili. Geofizikalne raziskave Tržaškega zaliva so pokazale, da je predplio-kvartarna (večinoma flišna) kamninska podlaga prekrita z nekaj de - set do nekaj sto metri plio-kvartarnega sedi - menta (Busetti et al., 2010a, 2010b; Morelli & Mosetti, 1968; Trobec et al., 2018) Relief fli - šne podlage v skrajnem vzhodnem delu zaliva je bil v večji meri izoblikovan med mesinijsko 30 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Considering the dynamics of the North Istra Ex - trusion Wedge, it would be quite possible that due to the extension in the south-eastern half of the wedge and the blockage opposite the Trieste parallelepiped, folding transverse to the extrusion would occur in the north-western half of the extrusion wedge, much like the Tinjan Extrusion Wedge (Placer, 2005, Fig. 3), where these folds are well developed (Figs. 4A and Fig. 5/9). The Tinjan Extrusion Wedge is a miniature pendant of the North Istra Extrusion Wedge, so we would expect several folds, or at least one large one between the Rokava fault and the south-eastern Trieste parallelepiped boundary, but these were not detected at surface mapping. Geophysical surveys of the Gulf of Trieste have shown that the Pre-Plio-Quaternary bed- rock (mostly flysch) is covered by tens to sever - al hundred meters of Plio-Quaternary sediment (Busetti et al., 2010a, 2010b; Morelli and Mosetti, 1968; Trobec et al., 2018). The relief of the flysch substrate in the easternmost part of the bay was formed to a great extent during the Messinian ero - sion phase and to a lesser extent during a short - er Pliocene erosion episode (Busetti et al., 2010a, 2010b). The complex formation of the relief indi - cates that the surface currents during periods of erosion generally flowed westward (Morelli and Mosetti, 1968), which is comparable to the direc - tion of the present-day river network in the ex - treme north-western part of Istra (i.e. Dragonja, Rižana, Glinščica/Rosandra, etc.). The youngest Late Pleistocene sedimentary sequences, deposit - ed just before the last transgression in the eastern and central part of the area of the present-day Gulf of Trieste, show the general direction of the wa - ter currents towards the south, with one channel even running roughly parallel to the present-day coastline of the eastern part of the Gulf of Trieste (Novak et al., 2020; Ronchi et al., 2023; Trobec et al., 2017). It is very difficult to compare Late Qua - ternary river networks with river networks on fly- sch due to the far younger geomorphology, where sedimentation plays a greater role in shaping the surface compared to erosion. The shape of the riv - er network in the Late Pleistocene was largely in- fluenced by the topography of the time (Ronchi et al., 2023), since in the area of the present-day Gulf of Trieste, the terrain rose to the northwest (Tro - bec et al., 2018) due to the Soča megafan from the last glacial maximum (Fontana et al., 2014, 2010, 2008), which also covers the south-eastern part of the Gulf of Trieste. Possible transverse folding in the south-eastern part of the Gulf of Trieste could therefore only be determined from the structural map of the contact between carbonates and flysch. erozijsko fazo ter deloma med krajšo pliocensko erozijsko epizodo (Busetti et al., 2010a, 2010b) Kompleksna izoblikovanost reliefa nakazuje, da so površinski tokovi v obdobjih erozije v splo- šnem tekli proti zahodu (Morelli & Mosetti, 1968), kar je primerljivo s smerjo današnje reč - ne mreže v skrajnem severozahodnem delu Istre (i.e. Dragonja, Rižana, Glinščica, itd.). Najmlaj - ša poznopleistocenska sedimentna zaporedja, ki so se odložila tik pred zadnjo transgresijo na vzhodnem in osrednjem delu današnjega obmo - čja Tržaškega zaliva, pa kažejo generalno smer vodotokov proti jugu, pri čemer je en kanal tekel celo približno vzporedno z današnjo obalno črto vzhodnega dela Tržaškega zaliva (Novak et al., 2020; Ronchi et al. 2023; Trobec et al., 2017). Poznokvartarne rečne mreže zelo težko primer - jamo z rečno mrežo na flišu, saj gre za precej mlajšo geomorfologijo, kjer ima sedimentacija večjo vlogo pri izoblikovanju površja v primer - javi z erozijo. Na obliko rečne mreže v poznem pleistocenu je v večji meri vplivala takratna paleotopografija (Ronchi et al., 2023), saj se je na območju današnjega Tržaškega zaliva teren dvigal proti severozahodu (Trobec et al., 2018) zaradi Sočine megapahljače iz zadnjega glacial - nega viška (Fontana et al., 2014, 2010, 2008), ki prekriva tudi jugovzhodni del Tržaškega zaliva. Morebitno prečno gubanje v jugovzhodnem delu Tržaškega zaliva, bi bilo torej mogoče ugotovi - ti le iz strukturne karte stika med karbonati in flišem. To je sicer objavil Carulli (2011, sl. 3), vendar je njegov izdelek pregleden, zato ga ni mogoče uporabiti v ta namen. Prečnodinarska cona povečane kompresije v zaledju črnokalske anomalije V tem poglavju so opisane deformacije, ki so v istrskem potisnem območju nastale zaradi dinamike severnoistrskega iztisnega klina. Tu je med črnokalsko anomalijo, ki je prostorsko blizu Kraškemu robu in Hrušico nastala cona povečane kompresije, ki v celoti prečka Zuna - njedinarski naluskani pas in sega še v čelni del Zunanjedinarskega narivnega pasu. Zaradi nju - ne specifične zgradbe in zaradi nasledstvenega značaja novih deformacij, so te v vsaki enoti opi - sane posebej. Samostojno poglavje je namenjeno Raškemu prelomu, ker je v njegovi prelomni coni povečana kompresija povzročila nastanek tran - spresivne antiklinale, ki se je iz kraške uravnave dvignila kot Vremščica (1027 m). 31 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria This was published by Carulli (2011, Fig. 3), but as his work represents a review article it cannot be used for this purpose. Transverse Dinaric zone of increased compression in the hinterland of the Črni Kal Anomaly This chapter describes the deformations that occurred in the Istra Pushed Area due to the North Istra Extrusion Wedge dynamics. Here, between the Črni Kal Anomaly, which is close to the Kraški rob, and Mt. Hrušica a zone of increased compres - sion has formed, which crosses the entire External Dinaric Imbricated Belt and extends into the fron - tal part of the External Dinaric Thrust Belt. Due to their specific structure and due to the heredi- tary nature of the new deformations, they are de - scribed separately in each unit. A separate chapter is devoted to the Raša Fault, because the increased compression of its fault zone caused the formation of a transpressive anticline, which rose from the karstic levelled terrain as Mt. Vremščica (1027 m). External Dinaric Imbricated Belt The External Dinaric Imbricated Belt in the territory under consideration is bounded by the Istra-Friuli Thrust-Underthrust Zone and the Ex - ternal Dinaric Thrust Belt boundary. (Fig. 1). The term »imbricated belt« is inappropriate for this part of the Dinarides because it doesn’t consist of imbricates (horses) but of folds. Nevertheless, the term is acceptable because horses characterize the rest of this belt in the External Dinarides. The Istra hinterland is made up of large, folded units, the Trieste-Komen and Čičarija Anticlinoria and the Vipava and Brkini Synclinorium. There is also slightly smaller Ravnik Anticlinorium. All of the listed units represent an example of complete (ideal) folding and are spatially displaced across compartments (Placer, 2005, Fig. 2), which means that equivalent folded structures do not lie in consecutive compartments but skip across the width of the compartment. The Vipava Synclinori - um continues in its direction into the Ravnik An - ticlinorium, the Trieste-Komen Anticlinorium into the Brkini Synclinorium, and the Čičarija Anticli- nor iu m i s e x p o s e d a nd do e s not t r a n s it i nto t he s y n - clinorium. In theory, complete folding is expressed in sets of linear folds displaced for a compartment (a set width). It usually covers larger homoge - neously constructed areas, but there are only two folded sets with a frontal anticlinorium and a rear synclinorium that are being displaced (offset). The term frontal refers to the thrust structure of the Di - narides: the Trieste-Komen frontal Anticlinorium Zunanjedinarski naluskani pas Zunanjedinarski naluskani pas je na obrav- navanem ozemlju omejen z istrsko-furlansko na - rivno-podrivno cono in mejo Zunanjedinarskega narivnega pasu (sl. 1). Termin »naluskani pas« je za ta del Dinaridov neustrezen, ker ga ne ses- tavljajo luske temveč gube, vendar je kljub temu sprejemljiv, ker so luske značilne za preostali del tega pasu v Zunanjih Dinaridih. Zaledje Istre je zgrajeno iz velikih nagubanih enot, Tržaško-Ko - menskega in Čičarijskega antiklinorija ter Vipa - vskega in Brkinskega sinklinorija. Tu je še Ravni - ški antiklinorij, ki je nekoliko manjši. Vse naštete enote predstavljajo primer popol - nega gubanja in so prostorsko zamaknjene po pre - dalih (Placer, 2005, sl. 2), kar pomeni, da ekviva - lentne nagubane strukture ne ležijo v zaporednih predalih, temveč preskakujejo za širino predala. Vipavski sinklinorij se po smeri nadaljuje v Rav - niški antiklinorij, Tržaško-Komenski antiklino - rij v Brkinski sinklinorij, Čičarijski antiklinorij pa je izpostavljen in se ne izteka v sinklinorij. V teoriji se popolno gubanje izraža v linearnih in predalčno zamaknjenih gubah in običajno zaje - ma obsežnejša homogeno zgrajena območja, tu pa gre za specifičen primer, kjer obstojata le dva na - gubana niza s čelnim antiklinorijem in začelnim sinklinorijem, ki sta zamaknjena. Termin čelni se nanaša na narivno zgradbo Dinaridov, Tržaško - -Komenski čelni antiklinorij se previje v začelni Vipavski sinklinorij, Čičarijski čelni antiklinorij se previje v začelni Brkinski sinklinorij, ta pa v Ravniški antiklinorij (sl. 9A). Predalčna nagubana zgradba ima določene za - konitosti, ki so zastopane tudi v našem primeru, pomembne so tri: 1. prehod antiklinale (antikli - norija) v sinklinalo (sinklinorij) in obratno, po smeri, se dogodi s cepljenjem gub, 2. v pravilni predalčni nagubani zgradbi se gube cepijo v preč - no ležeči coni, imenovani cona cepljenja gub (sl. 9A in 9B), 3. ekvivalentne strukture v predalčno nagubani zgradbi se povezujejo z navzkrižni - mi povezovalnimi gubami (nov termin), ki ima - jo usločeno os (undacija). Predalčno zamaknjeni antiklinali povezuje prečna antiklinala s konkav - no usločeno osjo, sinklinali povezuje sinklinala s konveksno usločeno osjo (sl. 9C). Cona cepljenja gub je nasproti predalčnim gubam manj deforma - bilna (sl. 9D). Vzrok za nastanek predalčne nagubane zgradbe v Zunanjedinarskem naluskanem pasu tiči v zgradbi in dinamiki Zunanjedinarske - ga narivnega pasu. Prečnodinarska cona cep - lenja gub se namreč nahaja v podaljšku sti - ka Snežniškega in Hrušiškega pokrova proti 32 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK folds into the rear Vipava Synclinorium, and the Čičari ja frontal Anticlinorium folds into the rear Brkini Synclinorium, which in turn folds into the Ravnik Anticlinorium (Fig. 9A). The compartment-like folded structure has certain regularities (rules), which are also pre - sented in our case, of which three are important: 1. the transition of an anticline (anticlinorium) to a syncline (synclinorium) and vice versa, according to direction, occurs by the splitting of folds. 2. in the correct crosswise-connecting folds, the folds are split in a transverse zone called the folds split- ting zone (Figs. 9A and 9B). 3. equivalent struc - tures in the crosswise-connecting folds are con- nected by crosswise-connecting folds (new term), which have a folded (buckled) axis (undation). The anticlines displaced by a compartment connect transverse anticlines with a concave folded axis, while synclines connect a syncline with a convex folded axis (Fig. 9C). The splitting folds zone is less deformable compared to the longitudinal folds (Fig. 9D). The cause of the formation of the compart - ment-like folded structure in the External Dinaric Imbricated Belt lies in the structure and dynamics of the External Dinaric Thrust Belt. The Trans - verse Dinaric folds splitting zone is located in the extension of the contact between the Snežnik and Hrušica Nappes towards the southwest in the di - rection of thrusting. There is no similar phenom - enon in the extension of the contact between the Hrušica and Trnovo Nappes, which could mean two things: that the position of the Transverse Di - naric folds splitting zone is accidental, or that the Hrušica Nappe extends far to the northwest under the Trnovo Nappe, and both nappes act together as a single unit. In contrast, the Snežnk Nappe under the Hrušica Nappe is expected to pinch out over a relatively short distance. That such an explanation is possible is shown by the hydrological connection between the Vipava River spring in the Hrušica Nappe and the sinks east of the Postojna basin in the Snežnik Nappe (Petrič et al., 2020). The Trno - vo and Hrušica Nappes are older than the Snežnik A B C D FOLDS SPLITTING ZONE Fig. 9. Compartment-like folded structure, folds splitting and cross - wise connecting folds: A. Structural sketch of the compartment-like folded territory of the External Dinaric Imbricated Belt. B. Folds splitting. C. Crosswise connecting folds: concavely bent anticline axis, convexly bent syncline axis; D. Reduced compressibility of the Senožeče Folds Splitting Zone. Sl. 9. Predalčna nagubana zgradba, cepljenje gub in navzkrižno-pov - ezovalne gube: A. Strukturna skica predalčno nagubanega ozemlja Zunanjedinarskega naluskanega pasu. B. Cepljenje gub. C. Navz - križno-povezovalne gube: konkavno usločena os antiklinale, kon - veksno usločena os sinklinale; D. Zmanjšana stisljivost senožeške cone cepljenja gub. 33 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria 0 2 4 km Fig. 10. Structural-geological map of the Senožeče Folds Splitting Zone. Updated after Jurkovšek et al. (1996; 2008; 2013) and Placer (2015). The updates do not interfere with the thrust structure. The key for the naming of the folds in Fig. 11. Sl. 10. Strukturno-geološka karta senožeške cone cepljenja gub. Dopolnjeno po Jurkovšek et al. (1996, 2008, 2013) in Placer (2015). Dopol - nitve ne posegajo v narivno zgradbo. Legenda poimenovanja gub na sl. 11. 34 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Nappe; this corresponds to the spatial lag between the Trieste-Komen and the Čičarij a Anticlinoria, as well as a temporal lag, since in the nappe struc - ture the younger units are formed below the older ones. In the Glinščica/Rosandra area, where the Trieste-Komen and Čičarij a Anticlinoria meet, the thrust structures of the latter lie below the thrust structures of the former. The area of the described splitting of folds is shown on a simplified structural map of the con - sidered territory (Fig. 10), from where it is trans - ferred to the digital model of the relief in Fig - ure 11. Based on previous research, we conclude (OGK, sheets: Gorica, Postojna, Ilirska Bistrica; Jurkovšek et al., 1996; Placer, 2015) that there are three major folds on the south-eastern margin of the Trieste-Komen Anticlinorium, which are also part of the north-western margin of the Brkini Synclinorium. For the sake of easier discussion, we have now named them. In Figures 10 and 11 they are marked with numbers, the Artvi že (3) and Gornje Leže če S y n c l i n e s ( 5 ) , a n d t h e F a m l - je Anticline (4). Senože če (7) and Laže Syncline (9), and Jelenje (8) and Razdrto Anticline (10) are clearly visible at the junction of the Vipava Syncli - norium and the Ravnik Anticlinorium. The latter is presented only in Figure 11. Between the Gornje Leže če and Senože če Synclines, there is an anti- cline that also belonged to this group of split folds; however, it lies in the wider zone of the Raša Fault and is therefore strongly deformed. In Figures 10 and 11 it is only symbolically presented and named after the Vremščica Paleo-Vremščica Anticline (6). jugozahodu v smeri narivanja. V podaljšku sti - ka Hrušiškega in Trnovskega pokrova ni po - dobnega pojava, kar bi lahko pomenilo dvoje, da je lega prečnodinarske cone cepljenja gub slučajna, ali pa, da se Hrušiški pokrov razteza pod Trnovskim pokrovom še daleč proti seve - rozahodu in delujeta obe krovni enoti skupaj kot enotna narivna gruda. V nasprotju s tem pa naj bi se Snežniški pokrov pod Hrušiškim kmalu izklinil. Da je taka razlaga mogoča, kaže hidrološka povezava med izvirom reke Vipa - ve v Hrušiškem pokrovu in ponori vzhodno od Postojnske kotline v Snežniškem pokrovu (Pe - trič et al., 2020). Trnovski in Hrušiški pokrov sta starejša od Snežniškega; to ustreza prostor - skemu zamiku med Tržaško-Komenskim in Či - čarijskim antiklinorijem, pa tudi časovnemu zamiku, saj v krovni zgradbi mlajše enote na - stajajo pod starejšimi. Na območju Glinščice, kjer se stikata Tržaško-Komenski in Čičarijski antiklinorij, narivne strukture slednjega ležijo pod narivnimi strukturami prvega. Območje opisanega cepljenja gub je prikaza - no na poenostavljeni strukturni karti obravna- vanega ozemlja (sl. 10), od koder je preneseno na digitalni model reliefa na sliki 11. Po dose - danjih raziskavah povzemamo (OGK, listi: Go - rica, Postojna, Ilirska Bistrica; Jurkovšek et al., 1996; Placer, 2015), da nastopajo na jugovzho - dnem obrobju Tržaško-Komenskega antiklinori - ja tri večje gube, ki so hkrati tudi del severoza - hodnega obrobja Brkinskega sinklinorija. Zaradi lažjega pogovora smo jih zdaj poimenovali, na Fig. 11. Geomorphology of the Senožeče Folds Splitting Zone. Sl. 11. Geomorfologija senožeške cone cepljenja gub. 1 External Dinaric Thrust Belt boundary, nappe boundary, nappe unit (T – Trnovo Nappe, H – Hrušica Nappe, S – Snežnik Nappe) / meja Zunanjedinarskega narivnega pasu, meja pokrova, pokrov (T – Trnovski pokrov, H – Hrušiški pokrov, S – Snežniški pokrov) 2 Istra-Friuli Thrust-Underthrust Zone / istrsko-furlanska narivno-podrivna cona 3 Črni Kal Anomaly / črnokalska anomalija 4 Two folds in the Črni Kal Anomaly influence zone: 1 – Bazovica Anticline, 2 – Lipica Syncline / gubi v vplivnem območju črnokalske anomalije: 1 – Bazovska antiklinala, 2 – Lipiška sinklinala 5 Subvertical NW striking faults (»Dinaric trend«) with a predominant shear offset component: IF – Idrija Fault, PF – Belsko Fault, RF – Raša Fault / subvertikalni prelomi dinarske smeri s pretežno zmično komponento premika: IF – Idrijski prelom, BF – Belski prelom, RF – Raški prelom 6 Compartment-like folded area: a – Čičarija Anticlinorium, b – Trieste-Komen Anticlinorium, c – Ravnik Anticlinorium, d – Brkini Syn - clinorium, e – Vipava Synclinorium / predalčno nagubano ozemlje: a – Čičarijski antiklinorij, b – Tržaško-Komenski antiklinorij, c – Ravniški antiklinorij, d – Brkinski sinklinorij, e – Vipavski sinklinorij 7 Splitting folds: 3 – Artviže Syncline, 4 – Famlje Anticline, 5 – Gornje Ležeče Syncline, 6 – Paleo-Vremščica Anticline, 7 – Senožeče Syn - cline, 8 – Jelenje Anticline, 9 – Laže Syncline, 10 – Razdrto Anticline / cepilne gube: 3 – Artviška sinklinala, 4 – Fameljska antiklinala, 5 – Gornjeležeška sinklinala, 6 – Paleovremška antiklinala, 7 – Senožeška sinklinala, 8 – Jelenja antiklinala, 9 – Laženska sinklinala, 10 – Razdrška antiklinala 8 Cross-connecting folds: 11 – Rodik-Preloka Anticline, 12 – Pared Syncline / navzkrižno-povezovalne gube: 11 – Rodiško-Preloška an - tiklinala, 12 – Paredska sinklinala 9 Undation of the nappe units: I – Nanos-Čaven antiform, II – Hrušica-Trnovo synform / undacija krovnih enot: I – nanoško-čavenska antiforma, II – hrušiško-trnovska sinforma 10 Sistiana Flexural Zone / sesljanska upogibna cona 35 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria 6 7 8 9 10 1 2 3 4 5 11 12 K r a š k i r o b K R A S Ilirska Bistrica Fig. 10 0 5 1 0 km BF 36 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK The considered folds splitting zone is several kilometres wide and lies transversely in the direc - tion of the Dinaric fold axes. It is named after the village of Senožeče – the Senožeče Folds Splitting Zone. The cross-connecting folds are partially pre - served between the Trieste-Komen and Čičarija Anticlinoria, and the Brkini Synclinorium and the flysch depression in front of the Trieste-Komen Anticlinorium. They can be seen in the junction between the Rodik and Preloka Anticlines, named the Rodik-Preloka Anticline (11), which has a con - cave folded axis, and a convexly folded syncline lying transversely to it, which runs between the Brkini Synclinorium and the depression in front of the Trieste-Komen Anticlinorium. We named it the Pared Syncline (12). The degree of curvature of the axes of cross-connecting folds is weak, so in some places they are not mapped at all. Between the Trieste-Komen and Ravnik Anticlinoria and the Vipava and Brkini Synclinoria the cross-con - necting folds are deformed along the Raša Fault. As was already noted, the Lipica Syncline (2) and the Bazovica Anticline (1) on the margin of the Trieste-Komen Anticlinorium do not belong to the theoretical model of the Senože če Folds Split- ting Zone. This assumption is also confirmed by the general structural setting, since there are no folds connecting the lagged Trieste-Komen and Čičarij a Anticlinoria southwest of the cross-con- necting Rodik-Preloka Anticline (11) and Pared Syncline (12). The formation of the two mentioned folds (1 and 2) is related to the Črni Kal Anom - aly, presumably with the antiformly bent Paleo - gene thrust surface in Glinščica/Rosandra area (Fig. 4A, area »a« ). Deformations that cannot be related to folds splitting but rather to an increased compression northeast of the Črni K a l A n o m a l y o c c u r i n t h e Senože če Folds Splitting Zone. The connection to the increased compression is obvious, as the gen - eral structures of the south-western part of the Senože če Folds Splitting Zone run parallel to the Črni Kal Anomaly (Fig. 1 1 ) , which a pplies to the extreme north-western part of the Čičari ja Anticli- norium and the Artvi že Syncline (3) in the Brkini Synclinorium and also for the Lipica Syncline (2) and Bazovica Anticline (1). The cross-connecting folds of the Rodik-Preloka Anticline (11) and the Pared Syncline (12) also have a modified position. We will not discuss the kinematic mechanism of the adjustment of the mentioned structures in the direction of the Črni Kal Anomaly herein, but it would certainly be necessary to conduct some slikah 10 in 11 so označene s številkami, tu le - žijo Artviška (3) in Gornjeležeška sinklinala (5) ter Fameljska antiklinala (4). Na stiku Vipa - vskega sinklinorija in Ravniškega antiklinorija so lepo vidne Senožeška (7) in Laženska sin - klinala (9) ter Jelenja (8) in Razdrška antikli- nala (10). Slednja je vidna le na sliki 11. Med Gornjeležeško in Senožeško sinklinalo je obsta - jala antiklinala, ki je tudi pripadala tej skupini cepilnih gub, vendar leži v širši coni Raškega preloma in je zaradi tega močno deformirana. Na sliki 11 je le simbolno zabeležena in poime - novana po Vremščici Paleovremška antiklinala (6) (Paleovremščica anticline). Izognili smo se izrazu Paleovremščiška, ker je neroden, izraz paleoantiklinala Vremščice pa bi odstopal od pridevniške rabe za ostale gube, ki je prijaznejša do slovenščine. Obravnavana cona cepljenja gub je široka nekaj kilometrov in leži prečno na osi gubanja Dinari - dov. Imenujemo jo senožeška cona cepljenja gub. Navzkrižno-povezovalne gube so delno ohra - njene med Tržaško-Komenskim in Čičarijskim antiklinorijem ter Brkinskim sinklinorijem in flišno udorino pred Tržaško-Komenskim antikli - norijem. Vidimo jih v povezavi med Rodiško in Preloško antiklinalo, poimenovano Rodiško-Pre - loška antiklinala (11), ki ima konkavno usločeno os in prečno nanjo ležečo konveksno usločeno sin - klinalo, ki poteka med Brkinskim sinklinorijem in udorino pred Tržaško-Komenskim antiklinori - jem. Poimenovali smo jo Paredska sinklinala (12). Stopnja ukrivljenosti osi navzkrižno-povezoval - nih gub je šibka, zato ponekod sploh niso kartira- ne. Med Tržaško-Komenskim in Ravniškim anti- klinorijem ter Vipavskim in Brkinskim sinklinori - jem sta navzkrižno-povezovalni gubi deformirani ob Raškem prelomu. Kot je bilo že rečeno, Lipiška sinklinala (2) in Bazovska antiklinala (1) na robu Tržaško-Komen - skega antiklinorija, ne sodita v teoretski model senožeške cone cepljenja gub. To predpostavko potrjujejo tudi splošne razmere, saj jugozahodno od navzkrižno-povezovalnih Rodiško-Preloške antiklinale (11) in Paredske sinklinale (12) ni gub, ki bi povezovale zamaknjena Tržaško-Ko - menski in Čičarijski antiklinorij. Nastanek obeh omenjenih gub (1 in 2) je povezan s črnokalsko anomalijo, domnevno z antiformno usločitvijo paleogenske narivne ploskve v Glinščici (sl. 4A, območje »a« ). V senožeški coni cepljenja gub nastopajo defor - macije, ki jih ne moremo povezovati s cepljenjem temveč s povečano kompresijo severovzhodno od 37 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Timavo / Timava River Isonzo / Soča River outflow UNDERGROUND FLOW OF THE Reka River abyss Reka River Dolnji Kras Gornji Kras ~ ~ ~ ~ ~ ~ ~ NOT TO SCALE Fig. 12. Sketch of the longitudinal geomorphological cross section of Kras region. Position of the profile in Fig. 2. Sl. 12. Skica vzdolžnega geomorfološkega profila Krasa. Lega profila na sl. 2. detailed structural research before answering this question. The effect of locally increased compression in the Dinaric hinterland of the Črni Kal Anomaly is also reflected in the longitudinal geomorpholog - ical profile of the Kras region (Fig. 12). Initially, the original peneplanation of the Trieste-Komen Plateau was sub-horizontal, whereas today it is inclined. From the Doberdob Plateau on the Spod - nji Kras at an elevation of about 110 m, it grad - ually rises towards Gornji Kras to about 440 m on the Divača Kras, where the rise terminates at the Matavun Fault Zone, along which the Škocjan structural bend was formed (Placer, 2015). Be - hind the Škocjan structural bend lies the plateau of Goriče K r a s ( a f t e r t h e v i l l a g e o f G o r i č e n e a r Famlje), which is not inclined but remains hor - izontal at around 440 m. Somewhat below this settlement, at an elevation of about 400 m, lies the Naklo level, as a remnant of the blind Vreme valley highest terrace. The Škocjan structural bend played an active role in the formation of the present Notranjska Reka (river) sinking area and the longitudinal profile of the Škocjan Caves. In the simplified structural map of the Karst (Placer, 2015), the term Škocjanski p rag (Škocjan tresh- old) was used for the structural bend, but it is not an elevation level, only an escarpment, which requires a new corresponding term. črnokalske anomalije. Povezava je očitna zato, ker so generalne strukture jugozahodnega dela seno- žeške cone cepljenja gub vzporedne črnokalski anomaliji (sl. 11), to velja za skrajni severozaho - dni del Čičarijskega antiklinorija in za Artviško sinklinalo (3) v Brkinskem sinklinoriju in za Li - piško sinklinalo (2) in Bazovsko antiklinalo (1). Spremenjeno lego imata tudi navzkrižno-povezo - valni gubi Rodiško-Preloška antiklinala (11) in Paredska sinklinala (12). Kakšen je bil kinemat - ski mehanizem prilagoditve omenjenih struktur smeri črnokalske anomalije v tem članku ne bomo razpravljali, vsekakor pa bi bilo potrebno pred odgovorom na to vprašanje, izvesti detajlne us - merjene strukturne raziskave. Učinek lokalno povečane kompresije v dinar - skem zaledju črnokalske anomalije se odraža tudi v vzdolžnem zbirnem geomorfološkem profilu Krasa (sl. 12). Prvotna uravnava Tržaško-Komen - ske planote je bila ob svojem nastanku subho - rizontalna, danes je nagnjena. Od Doberdob - ske planote na Spodnjem Krasu na višini okoli 110 m, se proti Gornjemu Krasu polagoma dviga do okoli 440 m na Divaškem Krasu, kjer se dviga - nje ustavi ob matavunski razpoklinsko-prelomni coni, po kateri je nastal škocjanski pregib (Placer, 2015). Za škocjanskim pregibom leži uravnava Goriškega Krasa (po vasi Goriče pri Famljah), ki ni nagnjena temveč ostaja na enaki višini okoli 38 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK External Dinaric Thrust Belt Figure 11 also shows part of the External Di - naric Thrust Belt with the Snežnik, Hrušica and Trnovo Nappes. According to the regional research data (OGK, sheets: Tolmin, Videm, Kranj, Gori - ca, Postojna; Mlakar, 1969), we conclude that the overlying thrust plane of the Trnovo Nappe bends transversely to the Dinarides, so that from south - west to northeast the Trnovo synform, the Idrija antiform, Žir i synform and the Poljane-Vrhnika antiform (Placer et al., 2021a) stand out. In Figure 11, only a part of the Trnovo synform (II) is visible, the axis of which continues towards the southeast into the Hrušica Syncline. It is not possible from the data on the geologic map to determine whether the underlying Hrušica Nappe thrust plane is also synformly bent. In the article on the relationship between tec- tonics and gravity phenomena at the boundary of the External Dinaric Thrust Belt (Placer et al., 2021a), it was established that the underlying thrust surfaces of the Hrušica Nappe below Nanos and the Trnovo Nappe below Mt. Čaven are con- vexly folded. The new terms Nanos and Čaven an- tiforms were introduced. Both therefore lie at the head of both thrust fronts, but they differ in ampli - tude – in the first it is around 250 m, in the second around 30 m. The Nanos and Čaven antiforms at the head of the Hrušica and Trnovo Nappe belong to the same antiform unit (Placer et al., 2021a), so it makes sense to introduce the term Nanos- Čaven antiform (Fig. 11, I). The relationship between them is not clear because the intervening space is denuded, and the Sistiana Flexural Zone also passes through it (Placer et al., 2021b), due to which the axis of the antiform is bent laterally and its convex part rests on the Belsko Fault (formerly Predjama fault, Plac - er et al., 2021a). The lateral bending of the Nanos- Čaven a n t i f o r m a n d t h e u n u s u a l c h a n g e o f t h e Belsko Fault trace are the result of the crossing of two Transverse Dinaric deformation zones in this area, the f lexural zone of the Sistiana Fault and the now described zone of increased compression in the Dinaric hinterland of the Črni Kal Anomaly. A more detailed description of the effect of the afore - mentioned deformations in this area is beyond the scope of this article, and to prove the existence of a zone of increased compression it is important to note that the Nanos segment of the Nanos- Čaven antiform has a significantly larger amplitude than the Čaven segment. 440 m. Nekaj pod to uravnavo leži na koti okoli 400 m nakelski nivo, ki je ostanek najvišje terase Vremske slepe doline. Škocjanski pregib je imel dejavno vlogo pri nastajanju sedanjega ponorne- ga območja notranjske Reke in vzdolžnega pro - fila Škocjanskih jam. V poenostavljeni struktur - ni karti Krasa (Placer, 2015) je bil za škocjanski pregib uporabljen termin škocjanski prag, vendar ne gre za višinsko stopnjo temveč le za pregib, ki terja ustrezno spremembo naziva. Zunanjedinarski narivni pas Na sliki 11 je viden tudi del Zunanjedinarske - ga narivnega pasu s Snežniškim, Hrušiškim in Trnovskim pokrovom. Po podatkih dosedanjih regionalnih raziskav povzemamo (OGK, listi: Tolmin in Videm, Kranj, Gorica, Postojna; Mla - kar, 1969), da krovna narivna ploskev Trnovske - ga pokrova undira prečno na Dinaride, tako da od jugozahoda proti severovzhodu izstopajo trno- vska sinforma, idrijska antiforma, žirovska sin - forma in poljansko-vrhniška antiforma, oziroma poljansko-vrhniški nizi (Placer et al., 2021a). Na sliki 11 je od naštetih viden le del trnovske sin - forme (II), katere os se proti jugovzhodu nada - ljuje v Hrušiško sinklinalo, medtem ko iz podat - kov na karti ni mogoče ugotoviti ali je sinformno usločena tudi krovna narivna ploskev Hrušiškega pokrova. V članku o odnosu med tektoniko in gravi - tacijskimi pojavi na meji Zunanjedinarskega na - rivnega pasu (Placer et al., 2021a) je bilo ugoto - vljeno, da sta krovni narivni ploskvi Hrušiškega pokrova pod Nanosom in Trnovskega pokrova pod Čavnom konveksno usločeni. Uvedena sta bila termina nanoška in čavenska antiforma. Obe torej ležita v čelu obeh pokrovov, vendar se razlikujeta po velikosti amplitude, pri prvi znaša okoli 250 m, pri drugi okoli 30 m. Nanoška in čavenska antiforma v čelu Hruši - škega in Trnovskega pokrova pripadata isti an - tiformni enoti (Placer et al., 2021a), zato je smi - selno uvesti termin nanoško-čavenska antiforma ( sl. 1 1 , I) . Odnos med n jima je nejasen zato, ker je vmesni prostor denudiran, preko njega pa po - teka tudi sesljanska upogibna cona (Placer et al., 2021b), zaradi katere je os antiforme bočno upog - njena, njen izbočeni del pa se naslanja na Belski prelom (prej Predjamski prelom, Placer et al., 2021a). Bočni upogib nanoško-čavenske antifor - me in nenavadna sprememba smeri Belskega pre - loma sta posledica križanja dveh prečnodinarskih 39 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Raša Fault In order to understand the deformations along the Raša Fault in the area of the Transverse Di - naric zone of increased compression between the Kraški rob and Hrušica, it is necessary to look at its trace from a greater distance. The Raša Fault trace (Fig. 1) is drawn on the Italian side accord - ing to Carulli’s (2006) data. On the Slovenian side, it is interpreted anew between Gorica and Dorn- berk, and from here to Vremščica by Poljak (2007), Jurkovšek et al. (1996), Jurkovšek (2010); Placer (2015), Placer et al. (2021b), and according to OGK data (sheets: Gorica, Trieste, Postojna and Ilirska Bistrica). Southeast of Vremščica, the Raša Fault trace is drawn on the basis of an exposed fault zone in the Stržen stream valley (Fig. 13) and on the basis of the interpretation of the formation of the pull-apart Ilirska Bistrica coal basin, which is said to have formed along the Raša Fault (Placer & Jamšek, 2011). In Figure 1, the visible part of the fault trace is marked with a solid line, and the invisible or presumed part with a dashed line. For the purposes of this article, it is import - ant to show in greater detail the conditions along the Raša Fault between Gorica and Vremščica (Fig. 13) and the Stržen valley. The damage zone is exposed in several places, in the village of Brdo near Dornberk (village) (Fig. 13, point 1), in the ravines and on the intermediate ridges between Tabor and Cvetrož village (Fig. 13, point 2), in the Zajčica road cut on the highway near Senožeče (Fig. 13, point 3), in three sand pits »V žlebu« (toponime) above Čepn o beneath the Mt. Vremšči - ca slope (Fig. 13, point 4) and along the Stržen (Fig. 13, point 5). There are also several small sand pits in the Raša valley next to the Raša Fault. The structure of the Raša Fault is best visible in the Zajčica terraced road cut on the highway near Senožeče (Fig. 13, point 3; Fig. 14), and was also revealed in a large, abandoned sand pit near the road cut. The entire fault zone, about 80 m wide, is exposed in the east wall of the road cut (Fig. 14A). Its major part is enlarged in Figure 14B. Here, an anticlinal fold is still visible in the third terrace. The anticline can be detected upon closer inspection of the entire roadcut. The first terrace riser is already built up and covered with grass, which is why Figure 14C shows the mirror image of the western wall of the road cut at the height of the first terrace, which is no longer there today but the mentioned anticline was clearly vis - ible here. In Figure 14D, the structure of the sec - tion is sketched with the stratigraphic data from Jurkovšek et al. (1996); on the left half, there is bedded Lipica Formation limestone (LF/K 2 4 -5 ), deformacijskih con na tem prostoru, upogibne cone Sesljanskega preloma in sedaj opisovane cone povečane kompresije v dinarskem zaledju čr - nokalske anomalije. Natančnejši opis učinka ome - njenih deformacij na tem prostoru presega okvir tega članka, za dokazovanje obstoja cone povečane kompresije pa je pomembno, da ima nanoški se - gment nanoško-čavenske antiforme bistveno večjo amplitudo od čavenskega segmenta. Raški prelom Za razumevanje deformacij ob Raškem pre - lomu v območju prečnodinarske cone poveča - ne kompresije med Kraškim robom in Hrušico, je potrebno pogledati na njegov potek z nekoliko večje razdalje. Trasa Raškega preloma (sl. 1) je na italijanski strani potegnjena po podatkih Caru - lli-ja (2006). Na slovenski strani je od Gorice do Dornberka interpretirana na novo, od tu do Vrem - ščice pa po podatkih Poljaka (2007), Jurkovška et al. (1996), Jurkovška (2010), Placerja (2015) in Placerja et al. (2021b), ter po podatkih OGK (listi Gorica, Trst, Postojna, Ilirska Bistrica). Jugovzho - dno od Vremščice je potegnjena na podlagi vidne prelomne cone v dolini potoka Stržena (sl. 13) in na podlagi interpretacije nastanka ilirskobistri- škega premogovnega pull apart-skega ali razmič - nega bazena, ki naj bi nastal ob Raškem prelomu (Placer & Jamšek, 2011). Na sliki 1 je vidni del tra - se označen s polno črto, nevidni ali domnevni del pa s prekinjeno črto. Za ta članek je pomembno, da podrobneje pri - kažemo razmere ob Raškem prelomu med Gorico in Vremščico (sl. 13) ter dolino potoka Stržena. Zdrobljena cona je vidna na več mestih, v naselju Brdo pri Dornberku (sl. 13, točka 1), v grapah in na vmesnih grebenih med Taborom in Cvetrožem (sl. 13, točka 2), v useku Zajčica na avtocesti pri Senožečah (sl 13, točka 3), v treh peskokopih »V žlebu« nad Čepnim pod Vremščico (sl. 13, točka 4) in ob potoku Strženu (sl. 13, točka 5). Tudi v dolini Raše je ob Raškem prelomu več manjših pe - skokopov. Najlepše je vidna zgradba Raškega preloma v terasastem useku avtoceste Zajčica pri Senože - čah (sl. 13, točka 3; sl. 14), razkrita pa je bila tudi v veliki jami nekdanjega peskokopa blizu useka. Na sliki 14A je fotografija vzhodne stene useka, kjer je vidna celotna zdrobljena cona preloma, široka okoli 80 m. Njen večji del je povečan na sliki 14B, tu je v ježi tretje terase kljub poruše - nosti še opazna antiklinalna guba, ki jo je pri bolj natančnem pregledu mogoče zaznati na ce - lotni višini useka. Ježa prve terase je že podzida - na in zatravljena, zato je na sliki 14C prikazana 40 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK gently dipping to the northeast, followed by two stronger subvertical fault planes with an interme - diate tectonized block, then the block folded into an asymmetric anticline slightly inclined to the southwest. Its wavelength is 20 m to 25 m with an amplitude of about 8 m. Towards the southwest, zrcalna podoba zahodne stene useka v višini ježe prve terase, ki je danes ni več. Tu je bila omenjena antiklinala lepo vidna. Na sliki 14D je zgradba useka skicirana, stratigrafski podatki so navedeni po Jurkovšku et al. (1996); na levi po - lovici so plasti Lipiške formacije (LF/K 2 4 -5 ), ki TKA VS FOB TKA, VS, FOB A A Fig. 18 Štanjel Štorje Goriče Škocjan RAŠA FAULT 0 5 1 0 km TF, KF, LF LF Fig. 13. Raša Fault between Gorica and the Stržen stream. Sl. 13. Raški prelom od Gorice do potoka Stržen. 1 Adjusting faults: TF – Tomačevo Fault, KF – Kobjeglava Fault, LF – Lukovec Fault / izravnalni prelomi: TF – Tomačevski prelom, KF – Kobjeglavski prelom, LF – Lukovski prelom 2 Sistiana Flexural Zone / sesljanska upogibna cona 3 Bent structures in the Sisitiana Flexural Zone: TKA – Trieste-Komen Anticlinorium axis, VS –Vipava Synclinorium axis, FOB – External DinaricThrust Belt front / upognjene strukture v sesljanski upogibni coni: TKA – os Tržaško-Komenskega antiklinorija, VS – os Vipavskega sinklinorija, FOB – čelo Zunanjedinarskega narivnega pasu 4 Profiles across the Raša Fault: A – A Štorje - Stomaž, B – B Povir - Griško polje, C – C Vremska dolina - Mt. Vremščica - Ravnik, D – D Košanska dolina, E – E Brezavščak stream valley / profili preko Raškega preloma: A – A Štorje - Stomaž, B – B Povir - Griško polje, C – C Vremska dolina - Vremščica - Ravnik, D – D Košanska dolina, E – E Dolina potoka Brezavščka 5 Observation sites of the Raša Fault: 1 – Brdo near Dornberk, 2 – Saksidi, 3 – Zajčica, 4 – Čepno, 5 – Stržen / mesta opazovanja Raškega preloma: 1 – Brdo pri Dornberku, 2 – Saksidi, 3 – Zajčica, 4 – Čepno, 5 – Stržen 41 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria the anticline limb lies on a subvertical fault plane, behind which lies a block of tectonized beds of the Lipica Formation. It is completed by a set of several parallel fault surfaces, behind which lie Liburnia Formation beds (LIB/K-Pc), already a part of the south-western block of the Raša Fault. As the Liburnian Formation makes a part of the Karst Group of Formations, the KGF is used in - stead of the LIB/K-Pc designation in Figure 14D. In the sand pit, right-lateral strike slip fault sur- faces with sub-horizontal slickensides and several completely flat subvertical tectonic mirrors, from a few metres to 25 m 2 in size, were observed in the Lipica Formation limestones. Tectonic mirrors were polished to a high gloss, and clearly indicate periodic polygonal movement of the fault blocks, confirmed also by barely visible striae in differ - ent directions. Signs of polygonal movement of the fault blocks were also observed in the fault zone of the Idrija Fault (Placer, 1980, fig. 12) and in the thrust plane of the Hrušica Nappe in the sand pit near Planina (Placer, 1994/95). In the profile sketch (14D), it is necessary to draw attention to the compatibility of the geologi - cal structure and the surface: on the left, the gentle slope of the upland adapts to the gently inclined bedding; the top of the upland lies above the top of the extruded anticline; and the steep slope on the right lies in the inner fault zone. From the condi - tions in the profile, we conclude that the relief here is the result of tectonic formation. Three successive sand pits opened in the lime - stones of the Lipica and Liburnia Formations (LF/ K 2 4 -5 , LIB/K-Pc), separated by the main fault plane of the damage zone of the Raša Fault in the »V žlebu« valley above Čepno villag e ( Fig . 1 3, po in t 4). The most telling are the fault surfaces in the middle sand pit, where horizontal tectonic slicken - sides occur, which indicate right-lateral strike slip motion and vertical slides with block movements in different directions. Other directions are also present. Flysch rocks occur in outcrops of the Raša Fault damage zone at Brdo near Dornberk (Fig. 13, point 1), between Tabor and Cvetrož (Fig. 13, point 2) and near Stržen (Fig. 13, point 5). In all cases, the main fault plane dips steeply towards the northeast; next to it lies a cut reverse flexure, which at first glance would indicate a simple re - verse movement, but conditions at Zajčica and Čepno s h o w t h a t o t h e r m o v e m e n t s a l s o e x i s t , s o conclusions based on a limited set of data can be deceptive. Without detailed research of different parts of the fault zone, it is not possible to discuss the kinematics of the blocks along the Raša Fault. položno vpadajo proti severovzhodu, sledita dve močnejši subvertikalni prelomni ploskvi z vme - snim zdrobljenim blokom, zatem blok naguban v asimetrično antiklinalo, ki je rahlo nagnjena proti jugozahodu. Njena valovna dolžina znaša okoli 20 m do 25 m, amplituda okoli 8 m. Proti jugozahodu se krilo antiklinale naslanja na sub- vertikalno prelomno ploskev, za katero je blok iz zdrobljenih plasti Lipiške formacije. Zaključi ga snop več prelomnih ploskev za katerimi leži - jo plasti Liburnijske formacije (LIB/K-Pc), ki že pripadajo jugozahodnemu bloku Raškega prelo - ma. Na sliki 14D je namesto Liburnijske forma - cije oznaka KGF (Kraška grupa formacij), katere del je tudi Liburnijska formacija. V peskokopu so bile v apnencih Lipiške formacije zabeležene des - nozmične prelomne ploskve s subhorizontalnimi tektonskimi drsami in več povsem ravnih, od nekaj do 25 m 2 velikih subvertikalnih tektonskih zrcal, ki so bila polirana do visokega sijaja, kar jasno kaže na občasno poligonalno premikanje prelomnih kril, ki so ga potrjevale tudi komaj vi - dne strije v različnih smereh. Znaki poligonalne - ga premikanja prelomnih kril so bili opazovani tudi v prelomni coni Idrijskega preloma (Placer, 1980, sl. 12) in v narivni ploskvi Hrušiškega po - krova v peskokopu pri Planini (Placer, 1994/95). V skici profila (14D) je potrebno opozoriti na skladnost geološke zgradbe in površja; na levi se položno pobočje vzpetine prilagaja položnim plastem, vrh vzpetine leži nad vrhom izrinjene antiklinale, strmo pobočje na desni leži v coni glavne prelomne ploskve. Iz razmer v profilu povzemamo, da je relief na tem mestu posledica tektonskega oblikovanja. »V žlebu« nad Čepnim (sl. 13, točka 4) so odprti trije zaporedni peskokopi v apnencih Li- piške in Liburnijske formacije (LF/K 2 4 -5 , LIB/ K-Pc), ki ju razdvaja glavna prelomna ploskev Raškega preloma. Najbolj povedne so prelomne ploskve v srednjem peskokopu, kjer nastopa - jo tektonske drse horizontalne smeri, ki kažejo na desno zmikanje in vertikalne drse z različno usmerjenimi premiki blokov. Prisotne pa so tudi druge smeri. Izdanki zdrobljene cone Raškega preloma v Brdu pri Dornberku (sl. 13, točka 1), med Ta - borom in Cvetrožem (sl. 13, točka 2) ter ob Str - ženu (sl. 13, točka 5), so v flišnih kamninah. V vseh primerih glavna prelomna ploskev strmo vpada proti severovzhodu, ob njej leži pretrgana reverzna fleksura, kar bi na prvi pogled kaza- lo na enostavni reverzni premik, vendar Zajči - ca in Čepno kažeta, da obstojajo tudi drugačni premiki, zato je sklepanje na podlagi omejenega 42 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK A B C D 43 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Only faulted rocks were observed in the outcrop next to Stržen (Fig. 13, point 5), but not the struc - ture of the fault zone or the kinematics. Displacements along the Raša Fault have not yet been investigated more precisely, but Jurkovšek et al. (1996, profile A – B) provides relatively reli - able information about the vertical displacement between the two fault blocks in the profile between the villages of Štorje and Stomaž, which amounts 150 to 200 m (measured from the cross-section on the map). The direction of the horizontal com - ponent of the displacement is right-lateral, but its magnitude has not yet been determined. In this article we are interested in the section of the Raša Fault, where the vertical uplift of its north-eastern block was measured (Jurkovšek et al., 1996, profile A – B). This profile is shown again (Fig. 15, profile A – A) for the sake of un - derstanding the topic under discussion. The men - tioned offset of 150 m to 200 m is significant be - cause it was determined on the basis of systematic mapping and a good knowledge of the thickness of the strata. However, since we are studying the re - lationship between tectonics and geomorphology, it was necessary to check whether a similar verti - cal movement also exists in the karst formations between the two blocks of the Raša Fault. A single karst ridge extends from Štanjel to Goriče pri Famljah, and plunges gently to the north - west in the south-western block of the Raša Fault in Figure 13. In the north-eastern block, there are fewer peneplained areas, which are found only in the vicinity of Senožeče, Volče and in Košanska do - lina valley (Fig. 18). For a comparison with profile A – A it was necessary to choose a control profile as close as possible to that of Štorje for the sake of credibility. As such, the B – B profile from Povir village through the Divača-Sežana lowland (about 390 m), the Mt. Sopada ridge, the Senadolski dol (a dol is usually an elongated shallow valley in Dinaric Karst), the Mt. Selivec ridge, and the flat Griško polje field (about 540 m) below Mt. Veliki Ognjivec (636 m) seemed suitable (Fig. 15, profile B - B). The difference in the peneplane elevations between the Divača - Sežana lowland and the Griško polje field is around 150 m. The bottom of Senadolski dol is not števila podatkov lahko varljivo; brez detajlnih raziskav različnih predelov prelomne cone ni mogoče govoriti o kinematiki blokov ob Raškem prelomu. V golici ob potoku Strženu (sl. 13, toč - ka 5) je bila zabeležena le prelomna porušitev, ne pa tudi zgradba prelomne cone ali kinema - tika. Premiki ob Raškem prelomu še niso bili na - tančneje raziskani, vendar podajajo Jurkovšek et al. (1996, profil A – B) sorazmerno zanes - ljiv podatek o vertikalnem premiku med obema prelomnima kriloma v profilu med Štorjami in Stomažem, ki znaša okoli 150 m do 200 m (iz - merjeno iz profila na karti). Smer horizontalne komponente premika je desna, vendar njena ve - likost še ni določena. V tem članku nas zanima odsek Raškega preloma, kjer je bil izmerjen vertikalni dvig njegovega severovzhodnega krila (Jurkovšek et al., 1996, profil A – B). Zaradi razumevanja obravnavane teme, ta profil ponovno prikazuje - mo (sl. 15, profil A – A). Omenjeni skok 150 m do 200 m je pomemben zato, ker je bil določen na podlagi sistematičnega kartiranja in dobrega poznavanja debeline plasti. Ker pa proučujemo razmerje med tektoniko in geomorfologijo, je bilo potrebno preveriti ali obstoja podoben ver- tikalni premik tudi pri kraških uravnavah med obema kriloma Raškega preloma. Na sliki 13 se v jugozahodnem krilu Raške - ga preloma razteza enotna kraška uravnava od Štanjela do Gorič pri Famljah, ki neznatno visi proti severozahodu. V severovzhodnem krilu je uravnanih površin manj, najdemo jih le v okolici Senožeč, v Volčah in v Košanski dolini (sl. 18). Za primerjavo s profilom A – A je bilo potrebno zaradi verodostojnosti izbrati kontrolni profil čim bliže Štorjam. Kot tak se je zdel primeren profil B – B od Povirja preko Divaško-Sežanske - ga podolja (okoli 390 m), grebena Sopade, Se - nadolskega dola, grebena Selivca in uravnanega Griškega polja (okoli 540 m) pod Velikim Og - njivcem (636 m). Razlika v koti uravnav med Divaško-Sežanskim podoljem in Griškim poljem znaša tu okoli 150 m. Dno Senadolskega dola ni primerno za primerjavo, ker je preoblikovano ob Fig. 14. Raša fault in the Zajčica roadcut (highway) (Figs. 13 and 18): A. Photo of the section. B. Part of the damage zone. C. Oblique anticline within the damage zone indicating reverse movement of the northeast limb. D. Sketch of the section: about 80 m wide Raša Fault damage zone. I – Southwestern boundary fault plane, which is also the main one; II, III, IV – internal fault planes; V – northeastern boundary fault plane. Key for the stratigraphic markers in Fig. 15. Sl. 14. Raški prelom v useku avtoceste Zajčica (sl. 13 in 18): A. Fotografija useka. B. Del zdrobljene cone. C. Poševna antiklinala znotraj zdrobljene cone, ki kaže na reverzni premik severovzhodnega krila. D. Skica useka: okoli 80 m široka zdrobljena cona Raškega preloma. I – jugozahodna mejna prelomna ploskev, ki je hkrati glavna; II, III, IV – notranje prelomne ploskve; V – severovzhodna mejna prelomna ploskev. Legenda stratigrafskih oznak na sl. 15. 44 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Straža Sopada Selivec Veliki Ognjivec Raša River Vremščica Markiževa gora 1 50m-200m SECTION A - A SECTION B - B Senadolski dol Brestovica Vremska dolina Volče Ravnik Griško polje 180 ° 230 ° 50 ° SECTION C - C 235 ° 55 ° 0 ° DRAJNA F. -300 Fig. 15. Profiles across the Raša Fault: A – A Štorje - Stomaž (after Jurkovšek et al. 1996, profile A – B); B – B Povir - Griško polje; C – C Vremska dolina - Vremščica - Ravnik, in the photo a handy model of the transpressive Vremščica Anticline; D – D Košanska dolina; E – Brezavšček stream valley. 1 Approximate level of comparative peneplanation. Sl. 15. Profili preko Raškega preloma: A – A Štorje - Stomaž (po Jurkovšek et al. 1996, profil A – B). B – B Povir - Griško polje; C – C Vremska dolina - Vremščica - Ravnik, na fotografiji priročni model Vremške transpresivne antiklinale; D – D Košanska dolina; E – E dolina potoka Brezavščka. 1 približni nivo primerjalne uravnave. 45 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria alluvium Sušica Brook Široki hrib Brezavšček Brook Vrtojba Orlek 1 SECTION D - D SECTION E - E 230 ° 50 ° 265 ° 95 ° Mh : Mv = 1 : 2,5 suitable for comparison, because it was transformed by the Raša Fault, nor is the flood plain near Dolenja vas village, which was transformed and deepened by the Senožeški potok stream. The second control profile C – C runs from Zavrhek village through the Vreme valley, across the Vremščica ridge to the part of the plateau at Volče (around 590 m) and over Mt. Markiževa gora to Ravnik peneplain (around 590 m) northeast of here (Fig. 15, profile C – C). The starting peneplanation level in the south-western block lies in the vicinity of Goriče pri Famljah vil - lage (around 440 m), but the profile does not cover it, so its projection on the profile plane is indicated. Also in this profile, the difference in the height of the settlements between Goriče, Volče, and Ravnik peneplain is about 150 m. Both control profiles therefore indicate that the difference in the height of the peneplained territory between the north-eastern and south-western blocks of the Raša Fault is com - parable to the geological offset in the A – A profile between Štorje and Stomaž. Raškem prelomu, primerna pa ni tudi naplavna ravnica pri Dolenji vasi, ki jo je preoblikoval in poglobil Senožeški potok. Drugi kontrolni pro - fil C – C poteka od Zavrhka preko Vremske do - line, čez greben Vremščice na del uravnave pri Volčah (okoli 590 m) in preko Markiževe gore na Ravnik (okoli 590 m) severovzhodno od tod. Izhodiščna uravnava v jugozahodnem krilu je v okolici Gorič pri Famljah (okoli 440 m), vendar je profil ne zajema, zato je nakazana njena pro - jekcija na profilno ravnino. Tudi v tem profilu znaša razlika v višini uravnav med Goričami ter Volčami in Ravnikom okoli 150 m. Oba kontrol - na profila torej kažeta na to, da je razlika v viši - ni uravnanega ozemlja med severovzhodnim in jugozahodnim krilom Raškega preloma primer - ljiva z geološkim skokom v profilu A – A med Štorjami in Stomažem. Profila D – D in E – E kažeta drugačno po - dobo. Profil D – D poteka prečno na Raški pre - lom jugovzhodno od Vremščice mimo Nove Su - šice, ki leži na uravnavi Košanske doline. Ta je v celoti v severovzhodnem krilu Raškega prelo - ma, trasa samega preloma pa poteka od Gornje Košane na golico št. 5 (sl. 13 in 18) ob strugi Stržena. Med Gornjo Košano in Strženom Ra - ški prelom ni zaznan v geomorfologiji terena, preseneča pa kota uravnave Košanske doline, ki znaša pri Novi Sušici okoli 440 m, kar je toliko kot v okolici Gorič pri Famljah severozahodno od Vremščice, to pa praktično pomeni, da se se - verovzhodno krilo Raškega preloma med Gor - njo Košano in Strženom ni dvignilo nad jugoza - hodnim krilom. Koti uravnav Košanske doline (okoli 440 m) in v okolici Gorič (okoli 440 m) sta približno enaki. Podoben ali enak, je podatek v profilu E – E preko doline Brezavščka med Gorico in Volčjo Drago, v katerem so povezani najvišji uravnani grebeni flišnega gričevja v jugozahodnem krilu Raškega preloma (Martinjak okoli 100 m, Bu - kovnik okoli 100 m in 110 m), s tistimi v seve - rovzhodnem krilu (Široki hrib okoli 100 m, La - movo okoli 100 m). Uravnana slemena in vrhovi na približno enako nadmorsko višino kažejo na večje uravnano flišno ozemlje, ki ga seka Ra - ški prelom, vendar brez vidnega vertikalnega premika. Flišna uravnava na tem območju ni povezana z uravnanim Krasom, vendar je od - nos med obema kriloma Raškega preloma mo - goče primerjati med seboj. Obravnavana flišna uravnava je omejenega obsega in se proti severu kmalu konča ob geomorfološki meji v smeri za - hod-vzhod. Ni raziskano ali gre za tektonsko ali erozijsko mejo. Fig. 15. continuation Sl. 15. nadaljevanje 46 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Profiles D – D and E – E provide a different picture. Profile D – D runs across the Raša Fault southeast of Mt. Vremščica past Nova Sušica vil - lage, which lies on the Košana valley plateau en- tirely on the north-eastern block of the Raša Fault (Fig. 15, profile D – D). The Raša Fault trace runs from Gornja Košana village to outcrop No. 5 (Figs. 13 and 18) along the Stržen. The Raša Fault is not detected in the geomorphology of the terrain be - tween Gornja Košana and Stržen, but the eleva - tion of the Košana valley is surprising, which is roughly 440 m near Nova Sušica village, as much as in the vicinity of Goriče pri Famljah northwest of Mt. Vremščica, which in practical terms means that the northeast block of the Raša Fault between Gornja Košana and Stržen did not rise above the south-western block. The peneplanation eleva - tions of the Košana valley (around 440 m) and in the vicinity of Goriče (around 440 m) are approxi - mately the same. The information in the profile E – E across the Brezavšček valley between Gorica and Volčja Dra - ga village is similar or identical (Fig. 15, profile E – E), where the highest levelled ridges of the f lysch hills in the south-western block of the Raša Fault (Mt. Martinjak about 100 m, Mt. Bukovnik about 100 m and 110 m) are connected, with those in the north-eastern block (Mt. Široki hrib about 100 m, Mt. Lamovo about 100 m). Level ridges and peaks at approximately the same altitude indicate a larg - er peneplained flysch area cut by the Raša Fault, but without visible vertical displacement. The pe - neplained flysch in this area is not related to the peneplained Karst, but the relationship between the two blocks of the Raša Fault can be compared with each other. The discussed peneplanation of flysch formation is of limited extent and soon ends to the north at the geomorphological boundary in the E–W direction. The question whether it is a tectonic or erosional boundary has not been inves- tigated. Let’s return again to profiles B – B and C – C in Fig. 15. In profile B – B, in addition to the already mentioned peneplanation in both blocks of the Raša Fault, there are four more hills, Mt. Straža (542 m) above Povir village, Mt. Sopada ridge, Mt. Selivec ridge, and Mt. Veliki Ognjivec ridge (636 m). Mt. Straža among the Tabor hills was formed due to selective corrosion and is built from less soluble rocks of the upper part of the Povir Formation (dolomite). As a result of selective cor - rosion, Mt. Sopada was also formed, as until re - cently it was covered by flysch, which is still visible along the Gabrk Fault (Jurkovšek et al., 1996). The formation of Mt. Selivec and Mt. Veliki Ognjivec, Vrnimo se ponovno k profiloma B – B in C – C na sliki 15. V profilu B – B so poleg že ome - njenih uravnav v obeh krilih Raškega preloma še štiri vzpetine, Straža (542 m) nad Povirjem, greben Sopade, greben Selivca in greben Velike - ga Ognjivca (636 m). Straža v Taborskih gričih je nastala zaradi selektivne korozije, zgrajena je iz manj topnih kamnin zgornjega dela Povirske formacije (dolomit). Zaradi selektivne korozije je nastala tudi Sopada, saj jo je še do nedavnega pokrival fliš, ki je še viden ob Gabrškem prelomu (Jurkovšek et al., 1996). Drugačen je nastanek Selivca in Velikega Ognjivca, med katerima leži Raški prelom. V prelomnih krilih vpadajo plasti v nasprotnih smereh in so ob Raškem prelomu najbolj strme, ko se pa od preloma oddaljujemo, je vpad vse manjši, pri tem pa je pomembno, da je hkrati z bolj strmo lego plasti dvignjen tudi relief. Pred seboj imamo transpresivno antikli - nalo, ki se je dvignila iz uravnanega sveta za- radi predisponirane lege plasti v coni Raškega preloma, imenujemo jo Selivška transpresivna antiklinala. Po zdrobljeni coni preloma je ero - zija ustvarila grapo, ki se izteka v dolino Raše. Grebena Selivca in Velikega Ognjivca sta ostanek vrha transpresivne antiklinale, ki jo je erozija po grapi med dviganjem razdelila na dva dela. Po taki analizi se Senadolski dol pokaže kot netipična asimetrična kraška depresija, njegovo jugozahodno pobočje je del Sopade in je nastalo zaradi selektivne korozije, severovzhodno po- bočje pa predstavlja krilo Selivške transpresiv - ne antiklinale, zaradi katere se je že uravnano površje izbočilo. Senadolski dol je torej kombi - nirana tvorba, ki v strukturnem smislu predsta - vlja korozijsko modificirano krilo tranapresiv - ne antiklinale. Podobnih in drugačnih dolov je na Krasu kar nekaj, brez dvoma pa bi jih našli tudi drugod, zato je smiselno, da tak genetsko mešani ali kombinirani kraški dol poimenujemo nevtralno, predlagamo termin kombinirani dol, kombidol ali komdol. Genetskih kombinacij, ki so prispevale k nastanku dolov je več, zato je nemogoče najti za vsako specifično kombinacijo posebno ime. Pred kratkim imenovani genetski tip dola razdol (Placer et al., 2021a), je nastal po snopu razpok ali po razpoklinski coni in je genetsko vezan samo na en fenomen. Ker gre za kraške pojave, je korozija dejavnik, ki ga ni tre- ba vključevati v termin. Termin pradol, ki so ga predlagali Diercks et al. (2021) je rečnoerozijska tvorba, tu imata struktura in korozija drugoten pomen. 47 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria between which lies the Raša Fault, is different. Layers in both fault blocks plunge in opposite di- rections and are steepest at the Raša Fault and become continuously less steep as we move away from the fault. It is important that with increased dip of the bedding, the relief is also raised. The described structure is a transpressive anticline, which rose from the peneplained relief due to the predisposed position of the strata in the Raša Fault zone, hence the transpressive Selivec Anticline. Along the damage zone erosion carved a canyon that runs into the Raša valley. The Mt. Selivec and Mt. Veliki Ognjivec ridges are the remains of the top of the transpressive anticline, divided into two parts by erosion along the fault during uplift. According to such analysis, Senadolski dol appears as an atypical asymmetric karst depres - sion, its south-western slope is part of Mt. Sopa - da and was formed by selective corrosion, while its north-eastern slope represents the limb of the transpressive Selivec Anticline, due to which the already levelled surface bulged. Senadolski dol is therefore a combined formation, which structural - ly represents a corrosion-modified limb of a trans - pressional anticline. There are a number of similar and different dols in the Kras, and can no doubt be found elsewhere as well, so it makes sense to name such a genetically combined karst dol neu - trally, thus we suggest the term combined dol called komdol (new term). There are several genet - ic combinations that contributed to the formation of dols, so it is impossible to find a special name for each specific combination. Razdol, one recent - ly-named genetic type of dol (Placer et al., 2021a) was formed in a fracture system or in a fault zone and is genetically related to only one phenome - non. Since these are karst phenomena, corrosion is a factor that does not need to be included in the term. The term pradol proposed by Diercks et al. (2021) is used for a dol formed by river erosion. Structure and corrosion are of secondary impor - tance here. On this occasion, it makes sense to point out that there are also dols that are entirely the result of folding: for example, »Vrhpoljski dol« between the Krvavi potok stream and the village of Vrhpol - je near Kozina, which is not a name given by the locals but represents a valley along the syncline, which is a secondary formation of the Materija Fault. Here we have a nice example of a folded pri - mary peneplanation, but since it is a karst relief, this type of valley or dol could be called a synclinal valley or sindol (new term). From the interpretation of the relief in profile B – B, it therefore follows that before the formation Ob tej priliki je smiselno poudariti, da obsto - jajo tudi doli, ki so v celoti posledica gubanja. Tak je npr. »Vrhpoljski dol« med Krvavim po - tokom in Vrhpoljem pri Kozini, ki ga domačini sicer tako ne imenujejo, predstavlja pa dolino po sinklinali, ki je sekundarna tvorba Matarskega preloma. Tu imamo lep primer nagubane pri - marne uravnave, ker pa gre za kraški relief, bi ta tip doline ali dola lahko imenovali sinklinalni dol ali sindol. Iz razlage reliefa v profilu B – B torej izha - ja, da je pred nastankom Raškega preloma, na nivoju profila, obstajala enotna kraška uravnava iz katere sta se dvigala samo grebena Taborskih gričev in Sopade. Po nastanku Raškega preloma in v fazi transpresije se je severovzhodno krilo preloma dvignilo, hkrati pa je nastala tudi tran - spresivna antiklinala, ki jo je omogočila ugodna lega plasti v krilih preloma, ki so že pred na - stankom Raškega preloma tvorile antiklinalo v sestavi senožeškega pasu cepljenja gub (sl. 11). Grapa po grebenu transpresivne antiklinale je lahko nastala samo v primeru, da je bila erozij - sko dejavna že pred transpresivnim dvigom, saj je ob dviganju izgubila hidrografsko zaledje. V profilu C – C je prikazana zgradba Vrem - ščice, ki je podobna Selivcu, le da je izhodna struktura izrazitejša, ker se Vremščica, oziro - ma območje, ki ga prikazuje profil C – C, na - haja bliže osrednjega dela senožeškega pasu cepljenja gub. V njem sta zajeti Gornjeležeška in Senožeška sinklinala, med katerima je pred na - stankom Raškega preloma ležala Paleovremška antiklinala. Po nastanku cepilnih gub je bilo ce - lotno ozemlje, skupaj s Fameljsko in Paleovrem - ško antiklinalo, uravnano. Za tem je poševno na Paleovremško antiklinalo (okoli 20°) nastal zmični Raški prelom, ob katerem se je, tako kot v primeru Selivca, v fazi transpresije dvignila transpresivna guba ob hkratnem dvigu seve - rovzhodnega krila preloma. Gubo imenujemo Vremška transpresivna antiklinala. V primeru Vremščice je zaradi obstoja vzporednega kraka ob Raškem prelomu, verjetno prišlo tudi do iz - rivanja vmesnega bloka. Tako pri Selivcu kot pri Vremščici, je bilo dviganje severovzhodnega kri - la Raškega preloma in transpresivne antiklinale, lahko enofazen ali večfazen proces, v vsakem primeru pa je Vremška transpresivna antiklina - la nasledstvena struktura Paleovremške antik - linale. V profilu C – C je tik ob Raškem prelomu še vidno njeno sleme. Fotografija pod profilom poenostavljeno ponazarja mehanizem nastanka Vremške antiklinale; položene talne plošče na tleh predstavljajo uravnano ozemlje, dve sta se 48 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK of the Raša Fault, at the level of the profile, there was a single karstic peneplanation from which only the ridges of the Tabor hills and Mt. Sopada rose. After the formation of the Raša Fault and during the transpression phase, the north-eastern block of the fault rose, and at the same time a transpres - sive anticline was formed, which was made pos - sible by the favourable position of the bedding in the fault blocks that already formed an anticline in the Senožeče Folds Splitting Zone before the formation of the Raša Fault (Fig. 11). The ravine along the crest of the transpressive anticline could only have formed if it was erosively active before the transpressive uplift, as it lost its hydrographic hinterland during the uplift. Profile C – C shows the building of Mt. Vremščica, which is similar to Mt. Selivec, except that the outgoing structure is more pronounced because Mt. Vremščica, or the area shown by profile C – C, is located closer to the central part of the Senožeče Folds Splitting Zone. It includes the Gornje Ležeče and Senožeče Synclines, be - tween which the Paleo-Vrem ščica Anticline took place before the formation of the Raša Fault. Af - ter the formation of split folds, the entire territo - ry, together with the Famlje and Paleo-Vrem šči- ca Anticlines, was levelled (peneplained). Afterwards, the Raša Fault was formed oblique - ly (around 20°) to the Paleo-Vrem ščica Anti- cline, along which, as in the case of Mt. Selivec, a transpressive fold rose during the transpres- sion phase at the same time as the north-eastern block of the Raša Fault rose. The fold is called the transpressive Vremščica Anticline. The in - termediate block was probably pushed out in the case of Mt. Vremščica, due to the existence of a parallel fault branch along the Raša Fault. Both at Mt. Selivec and at Mt. Vremščica, the up - lift of the north-eastern flank of the Raša Fault and the transpressive anticline may have been a single-phase or multiphase process, but in any case, the transpressive Vremščica Anticline is the successor structure of the Paleo-Vrem ščica Anticline. In profile C – C, its hinge is still visi - ble right next to the Raša Fault. The photo below the profile illustrates the formation mechanism of the Mt. Vrem ščica Anticline; laid floor slabs on the ground represent a levelled area, with two of them later rising due to the shrinkage of that part of the bridge construction on which the slabs are laid. The contact between them illus - trates the role of the Raša Fault. The transpressive Vrem ščica Anticline is sepa- rated from the Selivec Anticline by a saddle, which is conditioned by a less pronounced anticlinal pozneje dvignili zaradi krčenja dela konstruk - cije mostu, na katerem so plošče položene. Stik med njima ponazarja vlogo Raškega preloma. Vremška transpresivna antiklinala je od Seli - vške ločena s sedlom, ki je pogojeno z manj izra - zito antiklinalno lego plasti. Sedlo leži v bližini useka Zajčica (sl. 14) in nima imena, vendar ga zaradi lažjega sporazumevanja imenujemo Sena - dolsko sedlo. Transpresivna guba tu ni odsotna temveč le manj izrazita, profil Zajčica lepo poja - snjuje njegovo zgradbo. Domnevamo, da je zaradi transpresije dvig - njena tudi Markiževa gora med uravnavama okoli Volč in na Ravniku (sl. 15, profil C – C) . Razteza se ob Markiževem prelomu vzpored - no z Vremščico, le da je dvig tu skromnejši in asimetričen. Na obstoj Markiževega preloma posredno kažeta smer Markiževe gore in njeno dolgo, ravno, strmo severovzhodno pobočje, ki je verjetno zaradi hitrega dviga skoraj v celo- ti prekrito z deluvijem. Obstoj preloma podpira tudi izstopajoči linearni niz vrtač v smeri WNW - E S E, ki p o t e k a p r e k o m a n j š e u r a vn a v e s e v e - rozahodno od Markiževe gore proti Senožečam (sl. 16). Da gre za pomembnejšo mejo nakazu - jejo nizi vrtač v smeri NNW-SSE do N-S, ki se naslanjajo na omenjeni niz in so razviti v obeh krilih. Prostorska lega Markiževega preloma je vidna na sl. 18. 0 200 m Fig. 16. Markiž Fault. Position in Fig. 18. Sl. 16. Markižev prelom. Lega v prostoru na sl. 18. 49 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria position of the strata. The saddle is located near the Zajčica section (Fig. 14) and has no name, but for ease of communication we called it the Senadole saddle (after the village of Senadole). The transpressive fold is not absent here, but only less pronounced; the Zajčica profile nicely explains its structure. We assume that Mt. Markiževa gora was also raised between the levelled relief around Volče and on Ravnik peneplain (Fig. 15, profile C – C) due to transpression. It stretches along the Markiž Fault parallel to Mt. Vremščica, except that the rise here is less pronounced and asymmetrical. The exis - tence of the Markiž Fault is indirectly indicated by the direction of Mt. Markiževa gora and its long, flat, steep north-eastern slope, which is probably almost entirely covered by deluvium due to rapid uplift. The existence of the fault is also support - ed by a prominent linear series of dolines (usual - ly round sinkholes) in the WNW-ESE direction, which runs over a small plane northwest of Mt. Markiževa gora towards Senožeče (Fig. 16). The importance of the boundary is indicated by the series of dolines in the NNW-SSE to N-S direc - tion, which rest on the mentioned series and are developed in both fault blocks. The position of the Markiž Fault is presented in Figure 18. Before the uplift of Mt. Vremščica, the area around Goriče, Volče and Ravnik was levelled, as in the case of Mt. Selivec. Since it is more or less obvious that Mt. Selivec, Mt. Vremščica, and Mt. Tako kot pri Selivcu je tudi pri Vremšči - ci prvotno uravnano površje pred nastankom Vremščice, združevalo območja Gorič, Volč in Ravnika. Ker je več ali manj očitno, da so Seli - vec, Vremščica in Markiževa gora nastali zaradi povečane transpresije, domnevamo, da so zara - di nasledstvenih deformacij ob povečani tran - spresiji nastale tudi nekatere druge pozitivne in negativne reliefne oblike okoli danes obsto- ječih uravnav. Kraški relief opisovanega ozemlja je torej seštevek primarno uravnanega ozemlja, selektivne korozije, erozije in nasledstvene tek- tonike, kar pomeni, da je treba h genezi reliefa posameznih območij pristopati kompleksno. V profilu C – C je zajeta tudi flišna Gornjeležeška sinklinala, ki pripada Brkinskemu sinklinori - ju, zato jo je potrebno obravnavati drugače po litološki in strukturni plati. V sorazmerno sti - snjeni sinklinali so bili ugotovljeni znaki ver- tikalnega izrivanja jedra, ki ga povezujemo z učinkom transpresije. Ob regionalni cesti Vrem - ska dolina - Ribnica je nasproti vodarne Draga viden reverzni prelom 65/60, ki poteka v smeri osi Gornjeležeške sinklinale. Ob njem je videti tudi prevrnjene plasti. Območje ni detajlno kar - tirano, zato le sklepamo na obstoj konjugiranih dislokacij. Zaradi pomena omenjenega preloma za razumevanje zgradbe ozemlja, ga po bližnjem Drajnem potoku (sl. 18) imenujemo Drajni re - verzni prelom. Selivec Zajčica Vremščica a, b 2 1 b’ b a c 3 c c 4 b 5 a, b b Mh : Mv = 1 : 8 Sistiana Flexural Zone axis Adjusting structure boundry Fig. 17. Vertical displacement along the Raša Fault, based on the difference in elevation of the levelled areas: a – idealized starting level in the southwestern block of the Raša Fault; b – elevation level in the northeastern block of the Raša Fault (b´ – variant); c – Selivec and transpres - sive Vremščica Anticlines ridge level; 1 to 5 – observation sites along the Raša Fault. Sl. 17. Vertikalni premik ob Raškem prelomu, ki temelji na razliki v višinskem nivoju uravnav: a – idealizirani izhodiščni uravnani nivo v jugozahodnem krilu Raškega preloma; b – nivo uravnav v severovzhodnem krilu Raškega preloma (b´ – varianta); c – nivo slemena Selivške in Vremške transpresivne antiklinale; 1 do 5 – opazovalna mesta ob Raškem prelomu. 50 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Markiževa gora were formed due to increased transpression, we assume that some other posi - tive and negative relief forms around the existing levelled areas were also formed due to successive deformations in the zone of increased transpres - sion. The k a rst relief of t he de scr ib ed a re a is t here - fore the sum of a primarily regulated territory, selective corrosion, erosion, and successive tec- tonics, which means that the genesis of the relief of individual areas must be approached with this complexity in mind. The Gornje Leže če Syncline, covered in the C – C profile, belongs to the Brkini Synclinorium, so it needs to be treated differently in terms of lithology and structure. Signs of ver - tical core extrusion were found in the relatively tight syncline, associated with the transpression effect. A reverse fault 65/60 is exposed, running in the direction of the Gornje Ležeče Syncline axis along the Vremska dolina (Vreme valley) - Ribnica regional road, opposite the Draga water reservoir. Inverse bedding can also be seen next to it. The area is not mapped in detail, so we only infer the existence of conjugate dislocations. Due to the importance of the aforementioned fault for understanding the structure of the territory, it is called the reverse Drajna Fault after the nearby Drajna Stream (Fig. 18). The Divača and Gabrk Faults, visible in profiles B – B and C – C, are older than the Raša Fault. No deformation was found in the area that could be definitively related to successional offsets. The transverse profiles data is supplemented by a longitudinal schematically comparative geo - morphological profile, which combines the two fault blocks of the Raša Fault (Fig. 17). Such com - parison does not deal with real geomorphological data, but instead is meant to show the differenc - es in the absolute elevation of the compared lev - elled areas between the two fault blocks: between those in the south-western block are shown with a horizontal line »a«, and with a dashed line »b« in the north-eastern block, which in the individual profiles is offset from the line »a« as much as the difference in the absolute elevation of the levelled areas. The two lines completely overlap in the area between Gorica and Volčja Draga, and there is no comparative data on the villages of Volčja Draga and Štor je, but in the vicinity of Štorj e they are al- ready well apart, at around 150 m to 200 m. From Štorj e to Volče, the lines illustrating the elevations are separated, with the difference in elevation be- tween them around 150 m everywhere. They are reunited in the Košana valley. Line »a« is not only a construction aid but is very close its natural state, as the elevations of the Divaški in Gabrški prelom, ki sta vidna v profilih B – B in C – C, sta starejša od Raškega preloma. Na obravnavanem prostoru ob njima nismo opazili deformacij, ki bi jih brez vsakega dvoma lahko pripisali nasledstvenim premikom. Podatki prečnih profilov so dopolnjeni z vzdolžnim shematskim primerjalnim geomorfo - loškim profilom, ki združuje obe prelomni krili Raškega preloma (sl. 17). Tu ne gre za stvarne geomorfološke podatke temveč za prikaz razlik v absolutni višini primerjanih uravnav med obe - ma prelomnima kriloma; tiste v jugozahodnem krilu so prikazane z vodoravno črto »a «, v seve- rovzhodnem krilu s črto »b «, ki je v posameznih profilih toliko odmaknjena od črte »a «, kolikor znaša razlika v absolutni koti uravnav. Črti se povsem prekrivata na območju med Gorico in Volčjo Drago, od Volčje Drage do Štorij ni pri - merjalnih podatkov, vendar sta v bližini Štorij že krepko narazen, okoli 150 m do 200 m. Od Štorij do Volč sta črti, ki ponazarjata uravnave loče - ni, višinska razlika med njima je povsod okoli 150 m. V Košanski dolini sta ponovno združeni. Črta »a« ni le konstrukcijsko pomagalo, tem - več je zelo blizu stanja v naravi, saj sta koti urav - nav na območju Gorič in Košanske doline zelo blizu, okoli 440 m. Območje doline Brezavščka med Gorico in Volčjo Drago je izven take primer - jave, vendar vseeno ustreza kriteriju vertikalne- ga premika. Kakšen je potek črte »b « med Volčjo Drago in Štorjami ne vemo, lahko pa sklepamo, da se loči od črte »a « že daleč pred Štorjami, brez dvoma pa se ji ponovno priključi v Gornji Košani. Pre - den spregovorimo o tem si oglejmo strukturno skico Košanske doline na sliki 18. Raški prelom se od peskokopov »V žlebu« nad Čepnim (sl. 18, točka 4) spusti po geomorfološko močno odzivni grapi do Gornje Košane, od tu naprej proti strugi Sušice (sl. 18, točka 5) pa ga praktično na površ - ju ni mogoče zaznati. Skrivnost nenadne spre - membe v geomorfologiji tiči v reverznem pre - lomu, ki se v Gornji Košani odcepi od Raškega preloma in ga je potem mogoče slediti pod robom Košanskega hriba (589 m) najprej proti vzhodu in nato vzhodu-jugovzhodu do potokov Suši- ce in Stržena. Imenujemo ga Košanski reverzni prelom, v katerega čelu se je razvila Košanska antiklinala. Velikost premika ob Košanskem pre - lomu se od Raškega preloma proti vzhodu nag - lo zmanjšuje, kar pomeni, da gre za sekundarno tvorbo v širši coni Raškega preloma. Pomik ob Košanskem prelomu je pomemben zato, ker kaže, da se je prvotno enotno uravnano območje v se - verovzhodnem krilu preloma razdelilo na zgornji 51 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria G. Košana Volče Senožeče Sušica Sušica Barka MF RF RF MF R a v n i k V r e p o l j e R a v n i Drajni potok 1 2 3 4 5 6 0 10 20 km Fig. 18. Structural-geomorphological sketch of the Košana valley. Sl. 18. Strukturno-geomorfološka skica Košanske doline. 1 Fault: RF – Raša Fault, MF – Markiž Fault / prelom: RF – Raški prelom, MF – Markižev prelom 2 Reverse Drajna Fault / Drajni reverzni prelom 3 Reverse Košana Fault / Košanski reverzni prelom 4 Approximate adjustment level (approx. 440 m) / približna kota uravnave (ok. 440) 5 Neverke ramp / neverška klančina (rampa) 6 Observation site: 3 – AC Zajčica section, 4 – sand pits »V žlebu« above Čepno, 5 – Stržen valley / opazovalno mesto: 3 – usek AC Zajčica, 4 – peskokopi »V žlebu« nad Čepnim, 5 – dolina Stržena levelled areas of Goriče and the Košana valley are, at around 440 m, very close. The area of the Breza - všček valley between Gorica and the Volčja Draga valley is beyond such comparison, but still meets the criterion of vertical movement. We do not know what the course of line »b« is between Volčja Draga and Štorje , but we can con- clude that it separates from line »a« long before Štorje , and rejoins it at Gornja Košana village. Be - fore we talk further about it, let’s take a look at the structural sketch of the Košana valley in Figure 18. The Raša Fault descends from the »V žlebu « sand pits above Čepn o village (Fig. 18, point 4) along a geomorphologically strongly responsive ravine to Gornja Košana; from here in the direction of the Sušica riverbed (Fig. 18, point 5) it is practically impossible to detect it on the surface. The secret nivo okoli Volč (okoli 580 m) in spodnji nivo v Ko - šanski dolini (okoli 440 m). Povezuje ju pas danes nagnjene uravnave severno od Košanskega hriba. Nagnjeni povezovalni pas nekdaj enotne uravna- ve imenujemo po bližnjem naselju Neverke never - ška klančina ali neverška rampa. Vzhodno od sti - ka neverške klančine z uravnavo Košanske doline se v krovni grudi Košanskega reverznega prelo- ma dviga vzpetina, katere del je viden na sliki 18 (kota 467), ki ne potrjuje koncepta pojemanja re - verznega premika ob tem prelomu proti vzhodu. Anomalija je slej ko prej povezana s prelomom v smeri SW-NE, ki poteka preko sedla med dolina - ma reke Pivke in notranjske Reke (OGK, list Ilir - ska Bistrica; Šebela, 2005, sl. 1). Nanj se naslanja Košanski reverzni prelom. Natančnejša razlaga presega okvir tega članka. 52 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK of the sudden change in geomorphology lies in the reverse fault, which splits off from the Raša Fault at Gornja Košana village and can then be followed under Mt. Košanski hrib (589 m) first to the east and then east-southeast to the Sušica and Stržen streams. We named it the reverse Košana Fault, at the head of which the Košana Anticline devel- oped. The offset along the Košana Fault rapidly decreases from the Raša Fault to the east, which means that it is a secondary formation in the wider zone of the Raša Fault. The offset along the Košana Fault is important because it shows that the origi - nally uniformly levelled area in the north-eastern block of the fault was divided into an upper level around Volče (around 580 m) and a lower level in the Košana valley (around 440 m). They are con - nected by a belt of what is today the inclined plane north of Mt. Košanski hrib. The inclined connect - ing belt is called Neverke ramp after the nearby village of Neverke. An elevation rises in the hang - ing wall of the reverse Košana Fault, part of which can be seen in Figure 18 (elevation point 467), to the east of the junction of the Neverke ramp with the levelled Košana valley, which does not confirm the concept of a decrease in the offset along this reverse fault to the east. The anomaly is in one way or another related to a fault in the SW-NE direc - tion, which runs across the saddle between valleys of the Pivka and Reka rivers (OGK, sheet: Ilirska Bistrica; Šebela , 2005, fig. 1) and terminates at the reverse Košana Fault. A more detailed explanation is beyond the scope of this article. Line »b« in the longitudinal profile in Figure 17 therefore joins line »a« along the Neverke ramp. The discussion about where northwest of Štorje the effect of transpression along the Raša Fault should cease is theoretically interesting. A direct comparison with the Neverke ramp is not possi - ble, but a hypothetical discussion is possible, for which we find a basis in the discussion of the Sistiana Flexural Zone (Placer et al., 2021b). The left-lateral strike-slip Sistiana Fault in the seabed of the Gulf of Trieste has a WSW-ENE trend in the area of Sistiana Bay. The fault is wedged out at the north-eastern boundary of the Istra-Friuli Thrust-Underthrust Zone. Further to the north - east, a flexural zone was formed in that direction, where the Trieste-Komen Anticlinorium, the Vipa - va Synclinorium, and the frontal part of the Exter - nal Dinaric Thrust Belt are clearly bent (Fig. 13). The bending was the result of the movement of the Istran block towards the Dinarides, as its axis runs from Sistiana Bay towards the village of Spodnja Branica and Ajdovščina (Fig. 1). The Dinarides between the Sistiana and Kvarner Flexural Zones Črta »b« v vzdolžnem profilu na sliki 17 se torej priključi črti »a« po neverški klančini. Razprava o tem, kje severozahodno od Što - rij naj bi izzvenel učinek transpresije ob Raškem prelomu, je teoretično zanimiva. Neposredna primerjava z neverško klančino ni mogoča, mo - žna pa je hipotetična obravnava za katero najde - mo osnovo v razpravi o sesljanski upogibni coni (Placer et al., 2021b). Sesljanski levozmični pre - lom v podmorju Tržaškega zaliva poteka v smeri WSW-ENE, na območju Sesljanskega zaliva se izklini ob severovzhodni meji istrsko-furlanske narivno-podrivne cone, naprej proti sevrovzho- du pa se je v njegovi smeri izoblikovala upogib - na cona v kateri sta se lateralno vidno upognila Tržaško-Komenski antiklinorij, Vipavski sinkli - norij in čelni del Zunanjedinarskega narivnega pasu (sl. 13). Os upogiba poteka od Sesljanske - ga zaliva proti Spodnji Branici in Ajdovščini, nastala pa je zaradi pomikanja istrskega blo - ka proti Dinaridom (sl. 1). Območje Dinaridov med sesljansko in kvarnersko upogibno cono je bilo torej izpostavljeno povečani transpresiji in učinku raznolike nasledstvene tektonike. Ker je v s e s l j a n s k i u p o g i b n i c o n i b o č n o u s l o č e n t u d i Raški prelom, bi se v apikalnem delu usločitve, torej na območju Spodnje Branice, vsaj teoretič - no črta »b« lahko odcepila od črte »a«. Vendar os upogibne cone ni ozka, niti natančno dolo - čena, v najširšem smislu bi njen vpliv proti se - verozahodu lahko segal do severovzhodne meje izravnalne zgradbe Raškega preloma, torej do stičišča Tomačevskega preloma z Raškim prelo - mom (sl. 13). V tem primeru bi se črta »b« lahko odcepila od črte »a« že na območju Volčje Dra - ge. Za tako možnost govori deformacija flišnih plasti v Brdu pri Dornberku (sl. 13, točka 1). Za potrditev hipoteze bi bilo potrebno opraviti us- merjene terenske in modelne raziskave. Na sliki 17 sta za potek črte »b« od Selivca do meje iz - ravnalne zgradbe Raškega preloma nakazani dve možnosti, »b« in »b´ «. Dvig Selivca in ekstremni dvig Vremščice je na sliki 17 prikazan s črto »c«, ki shematsko sle - di njunemu slemenu in Senadolskemu sedlu med obema vzpetinama. Razmere na profilu na sliki 17 torej kažejo, da je transpresija dosegla naj - večji učinak na območju Vremščice. Poleg strukturnih kazalcev, da so Selivec, Vremščica in Markiževa gora antiklinalne, ali bolje antiformne deformacije prej uravnanega kraškega površja, obstajajo tudi krasoslovni po- kazatelji, ki pa še niso dovolj raziskani, da bi bili zanesljivi. Najpomembnejše so vrtače, ki so na u r a v n a n e m o z e m l j u p o g o s t e , n a z n a t n o n a g n j e n e m 53 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria were therefore exposed to increased transpression and the effect of diverse successional tectonics. Since the Raša Fault trace is also laterally bent in the Sistiana Flexural Zone, in the apical part of the folding, i.e. in the area of Spodnja Branica, line »b« could, at least theoretically, split off from line »a« (Fig. 13). However, the Sistiana Flexural Zone axis is neither narrow nor precisely defined; in the broadest sense its influence towards the northwest could extend as far as the north-eastern border of the Raša Fault adjusting structure i.e. to the junc - tion of the Tomačevo Fault with the Raša Fault (Fig. 13). In this case, line »b« could split off from line »a« already in the area of Volčja Draga village. The deformation of the flysch beds at the village of Brdo near Dornberk supports such a possibili - ty (Fig. 13, point 1). To confirm the hypothesis, it would be necessary to carry out focused field and model research. In Figure 17, two options are in - dicated for the course of line »b« from Mt. Selivec to the boundary of the Raša Fault adjusting struc- ture, »b« and »b’«. The uplift of Mt. Selivec and the extreme up - lift of Mt. Vremščica are represented by line »c« in Figure 17, which schematically follows their ridge and the Senadole saddle between the two eleva- tions. The conditions on the profile in Figure 17 therefore show that the transpression reached its greatest effect in the Mt. Vremščica area. In addition to the structural indicators that Mt. Selivec, Mt. Vremščica and Mt. Markiževa gora are anticlinal, or rather antiform deformations of the previously levelled karst surface, there are also karstological indicators that have not yet been suf- ficiently studied as to be considered reliable. The most important are dolines, which are common on flat land, yet absent or markedly rarer on a signifi - cantly tilted relief. Two tentative conclusions can be drawn from this: 1. dolines do not develop on slopes or only exceptionally under special condi - tions, and 2. dolines only develop on levelled relief and eventually disappear if the levelled relief tilts. The second assumption is more likely, because do - lines are often found on antiform hinges, which is a kind of confirmation of what has been said, since the antiform hinge maintains a more or less hori - zontal (untilted) position, but there are no dolines or there are significantly fewer on the slopes. The rare dolines on the slopes could be the remnants of the larger ones from the previous peneplanation, while the smaller ones may have already disap - peared. In this sense, we could interpret the sit - uation on Mt. Markiževa gora above the village of Volče (Fig. 18): its north-eastern slope is condi - tioned by a fault, so it is steep and covered with svetu jih ni ali pa so bistveno bolj redke. Iz tega je mogoče postaviti dva začasna sklepa: 1. vrtače se na pobočjih ne razvijejo ali le izjemoma kadar nastopijo posebni pogoji in 2. vrtače se razvijejo le na uravnanem svetu in sčasoma izginejo, če se uravnano ozemlje nagne. Verjetnejša je dru - ga domneva, pogosto namreč najdemo vrtače na slemenih antiform, kar je svojevrstna potrditev povedanega, saj ohrani sleme antiforme več ali manj vodoravno lego, na pobočjih jih pa ni ali jih je bistveno manj. Redke vrtače na pobočjih bi lahko bile ostanki večjih vrtač prvotne urav - nave, medtem ko so manjše morda že izginile. V tem smislu bi lahko interpretirali razmere na Markiževi gori nad Volčami (sl. 18), njeno seve - rovzhodno pobočje je pogojeno s prelomom, zato je strmo in pokrito z deluvijem, jugozahodno pobočje pa položnejše, na njem je nekaj manjših vrtač, vendar bistveno manj kot spodaj na urav - nanem Vrepolju pri Volčah, na slemenu pa sta dve večji vrtači. Lahko bi torej dejali, da so red - ke vrtače na jugozahodnem pobočju preostanek večjih vrtač, ki so obstajale pred dvigom. Pas ob Volčah in navzdol proti Košanskemu hribu je kultiviran in ni primeren za primerjavo. Preko Ravnika se na severovzhodni strani Markiževe gore vleče niz vrtač, ki kaže na brezstropo jamo (1), konča se ob severovzhodnem pobočju z veli - ko udorno tvorbo podobno zatrepu (2). Ta pokri - va celotno severno pobočje in del grebena, kar pomeni, da je nastala po dvigu Markiževe gore in je verjetno posledica sekundarnih procesov, zato ne ruši predlagane interpretacije. Vremščica in Selivec sta praktično brez večjih vrtač, obstajajo pa manjše, ki so na lidarju komaj zaznavne. Razmeroma enostavna razlaga pa je manj pre - pričljiva za Sopado za katero smo ugotovili, da ni nastala zaradi tektonskega dviga temveč za - radi selektivne korozije, saj je Sopado dolgo časa prekrival pokrov flišnih kamnin, katerega osta - nek je še viden ob Gabrškem prelomu v Brestovi - ci pri Povirju (sl. 15, profil B – B). Če zanemari - mo udornico Petnjak nad Brestovico, preseneča ena velika vrtača in nekaj manjših ter nizi vrtač v grapah. Vsi ti pojavi bi lahko nastali zaradi po - sebnih pogojev pri postopnem umikanju flišnega pokrova od slemena Sopade navzdol, vendar bi bilo treba to možnost še preučiti. Korelacija V coni povečane kompresije med črnokalsko anomalijo in Hrušico (sl. 11) so zaporedoma razvrščene naslednje strukturno-geomorfološke posebnosti: 1. deformirani severozahodni robovi 54 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK deluvium, while the south-western slope is flatter with a few small dolines, but significantly fewer than further below, on the levelled Vrepolje field near Volče, and there are two larger dolines on the ridge. It could therefore be said that the rare dol - ines on the south-western slope are the remnants of larger dolines that existed before the uplift. The zone along Volče and down towards Mt. Košanski hrib is cultivated and not suitable for comparison. A series of dolines stretches across the Ravnik plane north of Mt. Markiževa gora and indicate an unroofed cave (1), ending on the north-eastern slope with a large collapse form similar to a steep - head (2). It covers the entire northern slope and part of the ridge, which means that it was formed after the uplift of Mt. Markiževa gora and is prob - ably the result of secondary processes, so it does not affect the proposed interpretation. Mt. Vremščica and Mt. Selivec are practically free of larger dolines, but there are smaller ones that are barely detectable on the lidar. A relatively simple explanation, however, is less convincing for Mt. Sopada, which we found to have been formed not by tectonic uplift but by selective corrosion, as Mt. Sopada was covered by flysch rocks for a long time, so flysch remnants can still be seen next to the Gabrk Fault at the village of Brestovica pri Povirju (Fig. 15, profile B – B). Ig - nor ing t he collapse doline Petnja k above Brestov ic a pri Povirju, one large and several smaller dolines and series of dolines in the ravines are surpris- ing. All these phenomena could have formed due to special conditions during the gradual retreat of the flysch cover from the Mt. Sopada ridge down, but such a possibility should still be studied. Correlation In the zone of increased compression between the Črni Kal Anomaly and M t. Hrušica (Fig. 1 1 ) , the following structural-geomorphological pecu - liarities are sequentially classified: 1. the deformed north-western edges of the Brkini Synclinorium and the Čičarija Anticlinorium, 2. the Škocjan structural bend, which represents the highest part of the NW-tilted levelled karst surface (Fig. 12), 3. transpressive Selivec and Vremščica Anticlines (Fig. 15, profile B – B, profile C – C; Fig. 17) and 4. the Nanos part of the Nanos- Čaven antiform, which has a larger amplitude than the Čaven part. The interdependence of the described structur - al-geomorphological peculiarities is shown on the correlation diagram (Fig. 19), where their position on the common imaginary axis in the direction of N25° is given schematically. It is roughly per - pendicular to the local trend of the larger Dinaric Brkinskega sinklinorija in Čičarijskega antikli - norija, 2. škocjanski pregib, ki predstavlja naj - višji del proti NW nagnjene uravnave Krasa (sl. 12), 3. Selivška in Vremška transpresivna an - tiklinala (sl. 15, profil B – B, profil C – C; sl. 17) in 4. nanoški del nanoško-čavenske antiforme, ki ima večjo amplitudo od čavenskega dela. So - odvisnost opisanih strukturno-geomorfoloških posebnosti je prikazana na korelacijskem di - agramu (sl. 19), kjer je shematsko podana nji - hova lega na skupni namišljeni osi v smeri 25°. Ta je približno pravokotna na tukajšnjo smer večjih dinarskih struktur in poteka med hribom Zjat (449 m) na Kraškem robu nad Podpečjo in najvišjim vrhom Nanosa, Suhim vrhom (1313 m). V spodnjem delu diagrama je prika - zano vplivno območje črnokalske anomalije. Vse omenjene strukturno-geomorfološke poseb - nosti na korelacijskem diagramu ležijo v coni, ki je dolga okoli 40 km in široka okoli 10 km do 15 km. Zaradi prekrivanja strukturnih in geomorfoloških vrhuncev uvajamo namesto opisnega termina prečnodinarska cona pove - čane kompresije med črnokalsko anomalij in Hrušico, skrajšani termin traverza Kraški rob 10 km 25 ° Nanos Selivec Deformation of Trieste - Komen Anticlinorium SE Črni Kal Anomaly Deformation of Čičarija Anticlinorium NW Vremščica Škocjan Bend Artviže Syncline Suhi vrh 1313 m Zjat 449 m Fig. 19. Corelation diagram. Sl. 19. Korelacijski diagram. 55 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria structures and runs between Zjat hill (449 m) on the Kraški rob above the village of Podpeč and the highest peak of Mt. Nanos, Mt. Suhi vrh (1313 m). The influence area of the Črni K a l A n o m a l y i s shown in the lower part of the diagram. All of the mentioned structural-geomorpholog - ical features on the correlation diagram lie along a zone some 40 km long and 10 km to 15 km wide. Due to the overlap of structural and geomorpholog - ical peaks, instead of the descriptive term Trans - verse Dinaric zone of increased compression be - tween the Črn i Kal Anomaly and Mt. Hrušica«, we introduce the abbreviated term Kraški rob – Hruši - ca Traverse. For the sake of simplified use, we re - placed the term Črni Kal Anomaly with the term Kraški rob ( Žitko , 1990; Placer, 2007), with which it mainly overlaps (Fig. 11). The aforementioned zone of increased compression is not an exception within the Istra Pushed Area, as there is a dispro- portionately larger unit located in the hinterland of the South Istra Pushed Wedge. The Črni Kal Anomaly is a peculiarity, a special feature, which was the cause of the North Istra Extrusion Wedge formation. Without the discovery of the Črni Kal Anomaly and the zone of increased compression, we would not be able to explain the formation of Mt. Vremščica and other structural-geomorpho - logical peculiarities in it, e.g. structural character - istics of the Škocjan Caves sinking area. The Kraški rob - Hrušica Traverse spatial - ly overlaps with the Senož če Folds Splitting Zone. The overlap is not accidental, as the Črni Kal Anomaly between the fronts of the Trieste - Komen and Čičari ja Anticlinorium is an integral part of the Senože če F o l d s S p l i t t i n g Z o n e . I f w e look at the problem from the point of view of space shortening, the folds splitting zone is more (de - formed) than the synclinorium and anticlinorium next to it (Fig. 9D), so the deformations are more pronounced in it. In this article, we did not deal with the defor- mation kinematics of the north-western edges of the Brkini Synclinorium and the Čičarij a Anticli- norium, which is related to the Črni Kal Anomaly. The exposed position of the Ravnik Anticlinorium could also be the result of increased compression, as it lies in the traverse zone. There are still some problems, but the tectonic geomorphology of the Istra Pushed Area is still in its infancy. Formation of the North Istra Extrusion Wedge and South Istra Pushed Wedge The main cause of the formation of the North Istra Extrusion Wedge and the South Istra Pushed Wedge is the structure of the border area between - Hrušica. Izraz črnokalska anomalija smo za - radi poenostavljene rabe zamenjali s pokrajino Kraški rob (Žitko, 1990; Placer, 2007) s katero se v glavnem prekriva (sl. 11). Omenjena cona povečane kompresije ni izjema znotraj istrskega potisnega območja, saj se neprimerno večja na - haja v zaledju konice južnoistrskega potisnega klina, posebnost je črnokalska anomalija, ki je bila vzrok za njen nastanek. Brez odkritja čr - nokalske anomalije in cone povečane kompre - sije ne bi mogli razložiti nastanka Vremščice in drugih strukturno-geomorfoloških posebnosti v njej, npr. strukturnih značilnosti ponornega ob - močja Škocjanskih jam. Traverza Kraški rob - Hrušica se prostorsko prekriva s senožeško cono cepljenja gub. Prek - rivanje ni slučajno, saj je črnokalska anomalija med čeloma Tržaško-Komenskega in Čičarij - skega antiklinorija sestavni del senožeške cone cepljenja gub. Če gledamo na problem s strani krčenja prostora, je cona cepljenja gub bolj toga od sinklinorijev in antiklinorijev ob njej (sl. 9D), zato so deformacije tu povečane. V tem članku se nismo ukvarjali s kinema - tiko deformacije severozahodnih robov Brkin - skega sinklinorija in Čičarijskega antiklinorija, ki je povezana s črnokalsko anomalijo. Tudi iz - postavljena lega Ravniškega antiklinorija bi lah- ko kazala na posledico povečane kompresije, saj leži v območju traverze. Problemov je še nekaj, vendar je tektonska geomorfologija istrskega po - tisnega območja šele v povojih. Nastanek severnoistrskega iztisnega in južnoistrskega potisnega klina Glavni vzrok nastanka severnoistrskega izti- snega klina in južnoistrskega potisnega klina je zgradba mejnega območja med Mikroadrijo in Dinaridi v Istri v katerem ima posebno vlogo čr - nokalska anomalija. Uvodoma si najprej oglejmo standardni horizontalni presek ene izmed manj - ših narivnih lusk, ki so sestavni del istrsko-fur- lanske narivno-podrivne cone (sl. 20). Vzorčna narivna luska je omejenega obsega. Njeno čelo ima obliko loka, zato se bočno izklinja, premik ob narivni ploskvi je največji v njenem srednjem delu, kjer se razvije čelna antiklinala, ki tone proti obema bokoma (sl. 20A), lahko pa se pla - sti preprosto naslanjajo na narivno ploskev brez izrazite čelne antiklinale (sl. 20B). Med nariva - njem so zgornje luske s svojo težo izzvale nasta - nek spodnjih lusk, tako da se je izoblikoval splet lusk, ki je prikazan na sl. 20C. Iz tega sledi, da ležijo mlajše luske pod starejšimi. Taka zgrad - ba je značilna za čičarijski del istrsko-furlanske 56 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Microadria and the Dinarides in Istra, in which the Črni Kal Anomaly plays a special role. As an intro - duction, let us first take a look at the standard hori- zontal section of one of the smaller duplexes that are an integral part of the Istra-Friuli Thrust-Under - thrust Zone (Fig. 20). The sample thrust duplex is limited in scope. Its front has the shape of an arch, so it curves laterally, and the offset along the thrust plane is largest in its central part, where a fron- tal anticline develops and its axis (gently) plunges towards both flanks (Fig. 20A), but the layers can simply rest on the thrust plane without a distinct frontal anticline (Fig. 20B). During thrusting, the upper duplexes provoked the formation of the low - er scales with their weight, so that the scales-like network of duplexes was formed, which is shown in Fig. 20C. It follows that the younger scales lie below the older ones. Such a structure is typical for the Čičari ja part of the Istra-Friuli Thrust-Underthrust Zone. The frontal anticlines (the duplex cores) are from the oldest layers that come to the surface, in our case Paleogene limestone. The formation of the North Istra and South Is - tra Structural Wedges and their dynamic versions is shown schematically in Figure 21 in four sketch - es A, B, C and D. The first three show what hap - pened in the Paleogene, the last one in the Neo- gene, which extended into the recent period. Figure 21A shows the Trieste-Komen and Čičarija frontal Anticlines in the initial stage of the formation of the Trieste-Komen and Čičarija Anticlines. The two frontal anticlines had already shifted in the beginning, which is described in the chapter on thestructure of the External Dinaric Imbricated Belt. Figure 21B shows the beginning of the devel - opment of a single thrust zone, when two anticli - noria formed from the two anticlines. From the present-day structure it can be concluded that there was no direct connection between the fron- tal thrusts of the two offset folds, but that a series of thrust duplexes of monotonous structure was formed between them, in which the north-west - ern edges of the frontal anticlines of the Paleogene limestone were arranged in an echelon series. In the figure, the situation is simplified, whereby a situation developed where the envelope of the north-western flanks of the Paleogene limestone frontal anticlines was linear in two-dimension - al space, and the subvertical plane or enveloping plane »E« in three-dimensional space. The spatial arrangement of frontal anticlines from Paleogene limestone can be compared to a stack of firewood, where the sawn surfaces of individual logs create a constructed plane. That this is possible is shown narivno-podrivne cone. Čelne antiklinale so iz najstarejših plasti, ki izdanjajo na površje, v na- šem primeru je to paleogenski apnenec. Nastanek severnoistrskega in južnoistrskega strukturnega klina ter njunih dinamskih izve - denk je shematsko prikazan na sliki 21 v skicah A, B, C in D, prve tri kažejo dogajanje v pale - ogenu, zadnja v neogenu, ki se je podaljšalo v recentno obdobje. Na sliki 21A sta narisani Tržaško-Komenska in Čičarijska čelna antiklinala v začetni fazi na - stajanja Tržaško-Komenskega in Čičarijskega antiklinorija. Čelni antiklinali sta bili zamaknje - ni že v začetku, kar je opisano pri zgradbi Zuna - njedinarskega naluskanega pasu. 1 2 3 4 5 Fig. 20. Imbrication geometry: A. Ideal thrust sheet, variant with frontal anticline. B. Ideal thrust sheet, variant without frontal anti - cline. C. Imbricated zone (zone of multiple thrust sheets). Sl. 20. Geometrija luskanja: A. Idealna narivna luska, varianta s čelno antiklinalo. B. Idealna narivna luska, varianta brez čelne an - tiklinale. C. Narivna cona iz narivnih lusk. 1 Carbonates / karbonati 2 Flysch / fliš 3 Thrust plane / narivna ploskev 4 Overturned Anticline / prevrnjena antiklinala 5 Bedding: normal, inverse / plasti: normalne, inverzne 57 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria in the structural diagram in Figure 6. Therefore, a special type of building was created, for which we proposed the term composite building. Figure 21C shows the further development of the thrust structure. Erosion thrusts developed in front of the thrust zone front, such as the Iso- la Thrust, which initiated the formation of inter - layer thrust surfaces in the flysch (Fig. 8). As the last thrust unit of the Dinarides in this area, the reverse Buje Fault, or the Buje Thrust Sheet, was formed, which has all the characteristics of the ini - tial thrust unit, except that it is larger (Fig. 20). Five structural features indicate this: 1. The Savudrija-Buzet Anticline is the fron - tal anticline of the Buje Thrust Sheet, whose car - bonate core is visible from the Savudrija penin - sula to the Mirna valley before Buzet, where the limestone is covered by flysch layers in such a way that is typical for the carbonate cores of the initial thrust scales frontal folds in Figures 20A and 20C. The Savudrija-Buzet Anticline continues from Savudrija towards the northwest in the Gulf of Trieste seabed (Carulli, 2011, Fig. 3). The anti - cline is also indicated by the geophysical profile in the WSW-ENE direction (Busetti et al., 2012, Fig. 2). Figures 21C shows its presumed position at the time of its formation in the Paleogene. 2. The steep position of the reverse Buje Fault corresponds to the initial stage of thrust develop- ment. 3. Northeast verging reverse faults are visible in the cliff of the south-western coast of Strunjan Bay (Figs. 4A and 8). Judging by their position, they are related to the backthrusting in the hinter- land of the Buje reverse Fault. 4. Thicker sub-horizontal layers of calcarenite are visible in the flysch cliff between Piran and Fiesa, i.e. in the uplifted block between the reverse Buje Fault and its backthrusts. Internal rotation is developed along the internal structures paral- lel to lamination in these layers via interlayer slips (Placer et al., 2010, fig. 19). The slips of the hang - ing wall beds are directed in a southwestern di- rection (Figs. 4A and 8). The data is not evidence of thrusting or underthrusting, but interlayer slip- ping could have been established only before the formation of the reverse Buje Fault and its back - thrusts. The reverse Buje Fault is therefore related to the Paleogene thrusting. An interlayer thrust was discovered in the sub-horizontal bedding of the transitional marl between Paleogene limestone and flysch in Izola, which is the apparent equiv - alent of interlayer offsets in the cliff between Pi- ran and Fiesa, which we named the Izola Thrust (Figs. 4A and 8). Na sliki 21B je viden pričetek razvoja enotne narivne cone, ko sta iz antiklinal nastala antikli- norija. Iz današnje zgradbe je moč sklepati, da ni prišlo do neposredne povezave med čelnima na - rivoma obeh zamaknjenih gub, temveč, da je med njima nastal niz narivnih lusk monotone zgrad - be, v katerih so se severozahodni robovi čelnih antiklinal iz paleogenskega apnenca razporedili v ešalonski niz. Na sliki so razmere poenostavlje - ne, razvilo se je stanje, ko je ovojnica (envelopa) severozahodnih bokov čelnih antiklinal iz pale - ogenskega apnenca bila v dvodimenzionalnem prostoru lineara, v tridimenzionalnem prostoru pa subvertikalna planara ali ovojna ravnina (en - velopna ravnina) »E«. Prostorsko razporeditev čelnih antiklinal iz paleogenskega apnenca lahko primerjamo s skladovnico drv, kjer žagane plo - skve posameznih polen ustvarjajo konstruirano ravnino. Da je to mogoče je pokazano na struk - turnem diagramu na sliki 6. Nastal je torej pose - ben tip zgradbe za katerega smo predlagali ter - min zložbena zgradba. Na sliki 21C je prikazan nadaljnji razvoj na - rivne zgradbe. V predčelju narivne cone so se razvili erozijski narivi, kot npr. Izolski nariv, ki so injicirali nastanek medplastnih narivnih ploskev v flišu (sl. 8). Kot zadnja narivna enota Dinaridov na tem prostoru je nastal Bujski re - verzni prelom, oziroma Bujska narivna luska, ki ima vse značilnosti inicialne narivne enote, le da je velikih dimenzij (sl. 20). Na to kaže pet struk - turnih značilnosti: 1. Savudrijsko-Buzetska antiklinala je čelna antiklinala Bujske narivne luske, njeno karbo - natno jedro je vidno od Savudrijskega polotoka do doline Mirne pred Buzetom, kjer karbonat prekrijejo flišne plasti na tak način, kot je zna - čilno za karbonatna jedra čelnih gub inicialnih narivnih lusk na sliki 20A in 20C. Savudrijsko - -Buzetska antiklinala se od Savudrije proti seve - rozahodu nadaljuje v podmorju Tržaškega zaliva (Carulli, 2011, sl. 3). Na antiklinalo kaže tudi ge - ofizikalni profil v smeri WSW – ENE (Busetti et al., 2012, sl. 2). Na sliki 21C je prikazana njena domnevna lega ob nastanku v paleogenu. 2. Strmi vpad Bujskega reverznega preloma ustreza inicialnemu stadiju razvoja nariva. 3. V klifu jugozahodne obale Strunjanskega zaliva so vidni reverzni prelomi, ki vergirajo proti severovzhodu (sl. 4A in sl. 8). Po prostorski legi sodeč, kažejo na povratno narivanje v zaled - ju Bujskega reverznega preloma. 4. V flišnem klifu med Piranom in Fieso, to - rej v dvignjeni grudi med Bujskim reverznim prelomom in njegovimi povratnimi narivi, so 58 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK FRIULI BLOCK Paleogene Paleogene Paleogene Neogene FRIULI BLOCK ISTRA BLOCK ISTRA BLOCK flysch flysch a KVARNER BLOCK KVARNER BLOCK E E 0 10 20 km Fig. 21. Formation of the Črni Kal Anomaly, the North Istra Extrusion Wedge and the South Istra Pushed Wedge. Sl. 21. Nastanek črnokalske anomalije, severnoistrskega iztisnega klina in južnoistrskega potisnega klina. 59 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria 5. Folds are developed in the flysch between the reverse Buje Fault backthrusts and the Križ Thrust (Figs. 4A and 8). The Križ Thrust is a Paleogene structure associated with the interlayer Izola Thrust which represents an example of the interweaving of subhorizontal thrust planes in the flysch and inter- layer thrust planes. The vergence of the folds in the intermediate space between the reverse Buje Fault backthrusts and the Križ Thrust is mirror-like. In this case, the symmetry is not evidence of simultaneous formation, but indicates that the older folds were formed together with the Križ Thrust. Later, when the reverse Buje Fault backthrusts were formed, the folds that create the impression of symmetry were also formed. A broader explanation is given in the description of Figure 8. The Buje Thrust Sheet did not develop into a nappe thrust with a large offset along a subhori- zontal or gently sloping thrust plane but remained as its aborted unit at the end of the Dinarides thrust. Its extreme south-eastern part is today the vidne debelejše subhorizontalne plasti apnečeve - ga peščenjaka. V njih je po internih strukturah vzporednih laminam, razvita interna rotacija, ki je nastala zaradi medplastnih zdrsov (Placer et al., 2010, sl. 19). Zdrsi krovninskih slojev so usmerjeni proti jugozahodu (sl. 4A in 8). Poda - tek ni dokaz za narivanje ali podrivanje, toda medplastno drsenje se je lahko uveljavilo samo pred nastankom Bujskega reverznega preloma in njegovih povratnih narivov. Povezujemo ga torej s paleogenskim narivanjem. V Izoli je bil v subho - rizontalnih plasteh prehodnega laporja med pale - ogenskim apnencem in flišem odkrit medplastni nariv, ki je pojavni ekvivalent medplastnih pre - mikov v klifu med Piranom in Fieso, imenovali smo ga Izolski nariv (sl. 4A in 8). 5. Med povratnimi narivi Bujskega reverznega preloma in Križnim narivnim prelomom so v f lišu razvite gube (sl. 4A in 8). Križni narivni prelom je paleogenska struktura, povezujemo ga z Izolskim medplastnim narivnim prelomom, ki predstavlja Paleogene thrusting: A. Formation of shifted primal anticlines of the Trieste-Komen and Čičarija Anticlinoria and frontal reverse faults. B. Anticlines develop into anticlinoria. A jump of movements from the frontal thrust of the Čičarija Anticlinorium to the frontal thrust of the Trieste-Komen Anticlinorium is formed via an echelon set of reverse faults. A stacked structure is formed (updated after Placer et al., 2010, Fig. 25 A). A composite building is created. C. A segmented thrust zone is finally formed, the Buje Thrust Sheet is formed, which is the last (the most external) unit of the thrust structure of this part of the Dinarides with reverse Buje Fault in its front. The South Istra and North Istra Structural Wedges are formed (updated after Placer et al., 2010, Fig. 25 B). Paleogensko narivanje: A. Nastanek zamaknjenih izvornih antiklinal Tržaško-Komenskega in Čičarijskega antiklinorija ter čelnih reverznih prelomov. B. Iz antiklinal se razvijeta antiklinorija. Oblikuje se preskok premikov s čelnega nariva Čičarijskega antiklinorija na čelni nariv Tržaško-Komenskega antiklinorija preko ešalonskega niza reverznih prelomov. Nastane zložbena zgradba (dopolnjeno po Placer et al., 2010, sl. 25 A). C. Dokončno se oblikuje segmentirana narivna cona, nastane Bujska narivna luska, ki je zadnja enota narivne zgradbe tega dela Dinaridov. V njenem čelu Bujski reverzni prelom. Nastaneta južnoistrski in severniostrski strukturni klin (dopolnjeno po Placer et al., 2010, sl. 25 B). Neogene underthrusting and pushing: D. Formation of the South Istra Pushed and North Istra Extrusion Wedges. Neogensko podrivanje in potiskanje: D. Nastanek južnoistrskega potisnega in severnoistrskega iztisnega klina. 1 The segmented Microadria strike-slip faults: SF – Sisitiana Fault, KF - Kvarner Fault / zmični prelom segmentirane Mikroadrije: SF – Sesljanski prelom, KF – Kvarnerski prelom 2 Subsided fault block / ugreznjeno prelomno krilo 3 Paleogene thrust, reverse fault: BT – Buzet Thrust, BuF – reverse Buje Fault / paleogenski nariv, reverzni prelom: BT – Buzetski nariv, BuF – Bujski reverzni prelom 4 Paleogene thrust zone / paleogenska narivna cona 5 Neogene-recent Istra-Friuli Thrust-Underthrust Zone / neogensko-recentna istrsko-furlansla narivno-podrivna cona 6 Lateral slipping along primary thrust surfaces, along reverse faults and along envelope faults in the Črni Kal Anomaly / zmikanje po pri - marnih narivnih ploskvah, po reverznih prelomih in po ovojnih ali envelopnih prelomih v črnokalski anomaliji 7 Anticlines: TKA – Trieste-Komen Anticline, ČA – Čičarija Anticline, LA –Lim Anticline, a flanking asymetric fold along the Kvarner Fault (LA1 – axis in the axial plane, LA2 – axis in one of the bisector planes) / antiklinale: TKA – Tržaško-Komenska antiklinala, ČA – Čičarijska antiklinala, LA – Limska antiklinala, obprelomna asimetrična guba ob Kvarnerskem prelomu (LA1 – os v osni ravnini, LA2 – os v eni izmed simetralnih ravnin) 8 Anticlinoria: TKAm – Trieste-Komen Anticlinorium, ČAm – Čičarija Anticlinorium / antiklinoriji: TKAm – Tržaško-Komenski an - tiklinorij, ČAm – Čičarijski antiklinorij 9 Geological boundary, dip direction / geološka meja, smer vpada 10 Stacked structure / zložbena zgradba 11 Rellative offset direction / smer relativnega premikanja bloka 12 North Istra Extrusion Wedge extrusion boundary / meja izrivanja severnoistrskega iztisnega klina. 60 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK North Istra Structural Wedge. We assume that Mi - croadria was already segmented in the Paleogene. This is indicated by the absence of the Oligocene in Istra, which is very likely related to the post-thrust uplift of Istra along the Kvarner Fault. From the above data, it follows that the South Istra Struc- tural Wedge was also formed in the Paleogene. In the Neogene, the movement of Istra, or rath - er this part of Microadria, towards the Dinarides began, which resulted in the development of push - ing and underthrusting structures. The origin and direction of the deformations now change radically and run in the opposite direction of thrusting. In this process, the segmented Microadria faults also came to life, the most important of which are the Kvarner Fault and the Sistiana Fault in the terri- tory under consideration, between which lies the Istra block. Structural mapping of the selected ar - eas showed that the degree of thrusting and under- thrusting of the Istra block increases from north - west to southeast, which is illustrated by the degree of tectonization of the Istra-Friuli Thrust-Under - thrust Zone. This movement is smaller in the area of the Trieste parallelepiped, larger in the area of the North Istra Extrusion Wedge, and largest in the tip of the South Istra Pushed Wedge. Pushing and underthrusting is reflected in the formation of »pushed« reverse faults and in the folding of Pa - leogene thrust units. Both caused the uplift of the Kraški rob and the deformation of the Dinarides. The mechanism of folding and uplift of the Di - narides due to underthrusting and pushing of the Microadria has not yet been described in detail. Sketch D (Fig. 21D) shows the hypothesis of the formation of the South Istra Pushed and Nor th Istra Extrusion Wedges and envelope faults in the area of the Črni Kal Anomaly. The arcuate shape of the reverse Buje Fault trace and the resulting wedge- shaped south-eastern block should therefore have been designed already in the Paleogene (Fig. 21C). The Neogene movement of the Istra block towards the Dinarides provoked the development of the left-lateral strike-slip Sistiana and right-lateral strike-slip Kvarner Flexural Zones and the formation of pushed and underthrust zones. Within the Is - tra block itself, the wedge-shaped south-eastern part of the Buje Thrust Sheet provoked an extru - sion process that did not follow the disjunctive boundaries of the wedge. Its south-western margin slipped along the newly formed strike-slip Zam - bratija Zone at the head of the Buje Thrust Sheet, while its north-eastern margin slipped along the newly formed dextral strike-slip zone in the envel - oping plane of the Črni Kal Anomaly . The graphic in Figure 21D is a rough schematic of the reverse primer prepletanja položnih narivnih ploskev v flišu in medplastnih narivnih ploskev. Vergenca gub v vmesnem prostoru med povratnimi narivi Bujskega reverznega preloma in Križnim nariv - nim prelomom, je zrcalna. Simetrija v tem prime - ru ni znak hkratnega nastanka, temveč kaže na to, da so starejše gube nastale skupaj s Križnim narivom, ob nastanku povratnih reverznih pre - lomov Bujskega reverznega preloma, pa so zatem nastale tudi gube, ki ustvarjajo podobo simetrije. Pri opisu sliki 8 je podana širša razlaga. Bujska narivna luska se ni razvila v krovni nariv z daljšim premikom in položnejšim vpa - dom, temveč je ob zaključku narivanja Dinaridov ostala kot njihova abortirana enota. Njen skrajni jugovzhodni del predstavlja danes severnoistr- ski strukturni klin. Predpostavljamo, da je bila Mikroadrija v paleogenu že segmentirana, na to kaže odsotnost oligocena v Istri, kar je zelo verjetno povezano s postnarivnim dvigom Istre ob Kvarnerskem prelomu. Iz naštetih podatkov izhaja, da je bil v paleogenu zasnovan tudi juž - noistrski strukturni klin. V neogenu se je pričelo premikanje Istre, ozi - roma tega dela Mikroadrije, proti Dinaridom, v katerih so se zaradi tega razvile strukture po- tiskanja in podrivanja. Izvor in smer deforma - cij se sedaj radikalno spremenita in potekata v nasprotni smeri narivanja. V tem procesu oži - vijo tudi prelomi segmentirane Mikroadrije, pomembnejša med njimi sta na obravnavanem ozemlju Kvarnerski in Sesljanski prelom med katerima leži istrski blok. Strukturno kartiranje izbranih območij je pokazalo, da se stopnja poti - skanja in podrivanja istrskega bloka povečuje od severozahoda proti jugovzhodu. To se najlepše vidi v stopnji porušenosti istrsko-furlanske na- rivno-podrivne cone. Na območju tržaškega pa - ralelepipeda je manjša, na območju severnoistr - skega iztisnega klina večja, največja na območju konice južnoistrskega potisnega klina. Potiska - nje in podrivanje se odraža v nastajanju potisnih reverznih prelomov in v gubanju paleogenskih narivnih enot. Oboje je povzročilo dvig kraškega roba in deformacijo Dinaridov. Mehanizem gu - banja in dviganja Dinaridov zaradi podrivanja in potiskanja Mikroadrije še ni bil podrobneje opisan. Na skici D (sl. 21D) je podana hipoteza na - stanka južnoistrskega potisnega in severnois - trskega iztisnega klina ter ovojnih ali envelo- pnih prelomov v območju črnokalske anomalije. Ločna oblika Bujskega reverznega preloma in iz tega izhajajoča klinasta oblika njegovega jugo - vzhodnega boka, naj bi bila torej zasnovana že v 61 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria Buje Fault area, so it also appears in Figure 22. The formation of the South Istra Pushed Wedge is therefore the result of the movement of the North Istra Extrusion Wedge. The amount of displace - ment along the edges of the North Istra Extrusion Wedge is the same, but it is asymmetric along the edges of the South Istra Pushed Wedge; along the strike-slip Zambratija Zone it is equal to the dis - placement of the North Istra Extrusion Wedge and is relatively small, while it is incomparably larger along the strike-slip Kvarner Fault. This is exter - nally reflected in the formation of the extensive sigmoidal structure of the Kvarner Flexural Zone and the asymmetric Lim Anticline. The dynamics of this process are also confirmed by recent GNSS (Globa l Nav igation Satellite System) data, according to which the part representing the South Istra Pushed Wedge is moving north-north - east, i.e. parallel to the Kvarner Fault (Brancolini et al., 2019, fig. 1). A large asymmetrical anticlinal fold, called the Lim Anticline, developed along the Kvarner Fault. Its asymmetrical structure is pre - sented in Fig. 21D, sketch a; the axis in the axial plane is marked as LA1; and the axis in one of the symmetry planes is marked as LA2, and there are as many of these as there are layers. Due to a gentle bedding dip it is easy to determine anticline axis on the geological map only in the symmetry plane of the unconformity between the Eocene carbonates and clastites (Fig. 21D, fold LA2; Fig. 2), while the axis of the LA1 axial plane can only be construct - ed. When interpreting the current shape of the Lim Anticline it is also necessary to take into account the deformation due to movement along the left-lat - eral strike-slip Zambratija Zone. The Lim Anticline shape (Figs. 2 and 3) is therefore a combination of a flanking fold along the right-lateral strike-slip Kvarner Zone and the left-lateral strike-slip Zam - bratija Zone. By describing the role of the reverse Buje Fault, or the Buje Thrust Sheet it is, in the dynamic scheme of Istra, possible to answer the question of where the border of the Dinarides lies northwest of the Kvarner Fault. Formally, it would lie along the reverse Buje Fault, which is the most distal thrust of the Dinarides which, however, did not experience its full development. Which is why the Buje Thrust Sheet became a part of Microadria in the process of its underthrusting. Thus, the formal thrust bound - ary of the Dinarides in eastern Istra represents the south-western or external edge of the Istra-Friuli Thrust-Underthrust Zone, and in the area of the Gulf of Trieste its north-eastern or inner edge. The Kvarner Fault extends to the external edge, the Sistiana Fault to the internal edge, and with this the paleogenu (sl. 21C). Neogensko premikanje istr - skega bloka proti Dinaridom je izzvalo razvoj sesljanske levozmične in kvarnerske desnoz - mične upogibne cone ter nastajanje potisne in podrivne cone. Znotraj samega bloka je klinasta oblika jugovzhodnega dela Bujske narivne luske izzvala proces iztiskanja, ki pa ni sledil disjun- ktivnim mejam klina. Njegov jugozahodni rob je zdrsel po novonastali zambratijski levozmični coni ob čelu Bujske narivne luske, severovzho - dni rob pa po novonastali desnožnični coni v envelopni ravnini črnokalske anomalije. Grafi - ka na sl. 21D je v območju Bujskega reverznega preloma grobo shematska, tako je tudi na sl. 22. Nastanek južnoistrskega potisnega klina je torej posledica premika severnoistrskega iztisnega klina. Velikost premika ob robovih severnoistr - skega iztisnega klina je enaka, ob robovih južno - istrskega potisnega klina pa je asimetrična; ob zambratijski levozmični coni je enaka premiku severnoistrskega iztisnega klina in sorazmerno majhna, ob Kvarnerskem desnozmičnem prelo - mu pa neprimerljivo večja. Ta se navzven odraža v nastanku obsežne sigmoidalne zgradbe kvar - nerske upogibne cone in Limske asimetrične obprelomne antiklinale. Dinamiko tega procesa potrjujejo tudi recen - tni podatki GNSS (Global Navigation Satellite System) po katerih se del, ki predstavlja južno - istrski potisni klin, premika proti severo-seve - rovzhodu, torej vzporedno s Kvarnerskim prelo - mom (Brancolini et al., 2019, sl. 1). Razvila se je obsežna obprelomna guba, oziroma obprelomna antiklinala, ki smo jo poimenovali Limska. Nje - na zgradba je asimetrična (sl. 21D, skica a), os v osni ravnini je označena z LA1, os v eni izmed simetrijskih ravnin pa z LA2, teh je toliko koli - kor je plasti. Na površinski karti Istre je zaradi blagega vpada plasti mogoče hitro in enostavno določiti le os v simetralni ravnini diskordančne - ga stika med eocenskimi karbonati in eocenski - mi klastiti (sl. 21D, guba LA2; sl. 2), medtem ko je mogoče os osne ravnine LAl le konstruirati. Pri razlagi sedanje oblike gube pa je potrebno upoštevati tudi deformacijo zaradi premika ob zambratijski levozmični coni, Limska antiklina - la na slikah 2 in 3 je torej kombinacija obpre - lomne gube ob kvarnerski desnozmični coni in zambratijski levozmični coni. Z opisom vloge Bujskega reverznega preloma, oziroma Bujske narivne luske, v dinamični she - mi Istre, je mogoče dati odgovor na vprašanje, kje poteka meja Dinaridov severozahodno od Kvarnerskega preloma. Formalno po Bujskem reverznem prelomu, ki je skrajni zunanji nariv 62 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK Črni Kal Anomaly acquires a meaning that must be investigated from other aspects as well, e.g. sedi - mentological. At the moment, we can only suggest that the informal and temporary boundary between the Dinarides and the Adriatic promontory runs along the Črni Kal Anomaly. Considering the offset between the Tri - este-Komen and the Čičarij a Anticlinoria, which caused the Črni Kal Anomaly, we believe that the Istra-Friuli Thrust-Underthrust Zone is only so wide in the Istra block. The Zone should therefore be narrower northwest of the Sistiana Fault, but this aspect has not yet been investigated. Dynamic model A structural geometry of the Istra block and the south-western part of the Istra Pushed Area sketch is presented in Figure 22. At first glance, the re - lation between the autochthon ( sensu stricto and sensu lato), that is, Microadria, and the Dinarides is noticeable. The only original deformations of the autochthon sensu stricto are the Sistiana and Kvarner Faults, both of which lie transversely to Dinaridov, vendar ta ni doživel popolnega ra - zvoja. Zato je Bujska narivna luska v procesu podrivanja Mikroadrije postala njen aktivni del. Tako predstavlja formalno narivno mejo Dinari - dov v vzhodni Istri jugozahodni ali zunanji rob istrsko-furlanske narivno podrivne cone, na ob- močju Tržaškega zaliva pa njen severovzhodni ali notranji rob. Kvarnerski prelom sega do zu - nanjega roba, Sesljanski prelom do notranjega roba, s tem pa dobi črnokalska anomalija pomen, ki ga je treba raziskati tudi z drugih vidikov, npr. sedimentološkega. V tem trenutku lahko le predlagamo, da poteka neformalna in začasna meja med Dinaridi in jadranskim predgorjem po črnokalski anomaliji. Glede na zamik med Tržaško-Komenskim in Čičarijskim antiklinorijem, zaradi katerega je nastala črnokalska anomalija, menimo, da je istrsko-furlanska narivno-podrivna cona tako široka le na območju istrskega bloka. Severoza - hodno od Sesljanskega preloma naj bi bila torej ožja, vendar je v tem smislu še neobdelana. Fig. 22. Dynamic model of the Kraški rob - Hrušica Traverse formation. Sl. 22. Dinamski model nastanka traverze Kraški rob - Hrušica. 1 Thrusting classification: autochthon sensu stricto, autochthon sensu lato, allochthon / narivna razčlenitev: avtohton sensu stricto, avtoht- on sensu lato, alohton 2 External Dinaric Thrust Belt boundary / meja Zunanjedinarskega narivnega pasu 3 A thrust (plane) in the External Dinaric thrust boundary zone: BuF – reverse Buje Fault, BT – Buzet Thrust / nariv v coni narivne meje Dinaridov: BuF – Bujski reverzni prelom, BT – Buzetski narivni prelom 4 Istra-Friuli Thrust-Underthrust Zone / istrsko-furlanska narivno-podrivna cona 5 Črni Kal Anomaly, the informal boundary between autochthon sensu lato and allochthon / črnokalska anomalija, neformalna meja avtoht - ona sensu lato in alohtona 6 The segmented Microadria strike-slip faults: SF – Sistiana Fault, KF – Kvarner Fault / zmični prelom segmentirane Mikroadrije: SF – Sesljanski prelom, KF – Kvarnerski prelom 7 Secondary subsided block of the Kvarner Fault / sekundarno ugreznjeno krilo Kvarnerskega preloma 8 Right lateral strike-slip longitudinal faults: RF – Raša Fault, IF – Idrija Fault / dinarski desnozmični longitudinalni prelom: RF – Raški prelom, IF – Idrijski prelom 9 Direction of secondary strike-slip movement / smer sekundarnega zmikanja 10 Axis of the flexural zone and the inferred position of the Sistiana and Kvarner Faults beneath nappe units of the External Dinarides: SFZ – Sistiana Flexural Zone, KFZ – Kvarner Flexural Zone / os upogibne cone in domnevna lega Sesljanskega in Kvarnerskega preloma pod narivnimi enotami Zunanjih Dinaridov: SFZ – sesljanska upogibna cona, KFZ – kvarnerska upogibna cona 11 Anticline: LA2 – Lim Anticline (axis in one of the bisector planes), SbA – Savudrija- Buzet Anticline, ViA – East Istra Anticline / 11 antiklinala: LA2 – Limska antiklinala (os po eni od simetralnih ravnin), SbA – Savudrijsko-Buzetska antiklinala, ViA – vzhodnoistrska antiklinala 12 Anticlinorium, synclinorium: a – Trieste-Komen Anticlinorium, b – Čičarija Anticlinorium, c – Ravnik Anticlinorium, d – Vipava Syn - clinorium, e – Brkini Synclinorium / 12 antiklinorij, sinklinorij: a – Tržaško-Komenski antiklinorij, b – Čičarijski antiklinorij, c – Ravniški antiklinorij, d – Vipavski sinklinorij, e – Brkinski sinklinorij 13 Area of the Kraški rob - Hrušica Traverse / območje traverze Kraški rob - Hrušica 14 Structural-geomorphological trajectory / strukturno-geomorfološka trajektorija 15 North Istra Extrusion Wedge limit of extrusion / meja izrivanja severnoistrskega iztisnega klina 16 External boundary of the Mesozoic carbonate platform / zunanja meja mezozojske karbonatne platforme 17 Relative direction of movement of the South Istra Pushed and North Istra Extrusion Wedges / relativna smer premikanja južnoistrskega potisnega in severnoistrskega iztisnega klina 18 Exposed peaks: SV– Mt. Suhi vrh (1313 m), V – Mt. Vremščica (1027 m), A – Mt. Ajdovščina (804 m) and Mt. Artviže (817 m), S – Mt. Slavnik (1028 m), U – Mt. Učka (1394 m), VP – Mt. Veliki Planik (1272 m), G – Mt. Gomila (1241 m), VS – Mt. Veliki Snežnik (1796 m) / izpostavljeni vrhovi: SV – Suhi vrh (1313 m), V – Vremščica (1027 m), A – Ajdovščina (804 m) in Artviže (817 m), S – Slavnik (1028 m), U – Učka (1394 m), VP – Veliki Planik (1272 m), G – Gomila (1241 m), VS – Veliki Snežnik (1796 m). 63 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria SV V A S VS G VP U BuF ViA 0 10 20 km KFZ SFZ KFZ 64 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK the Dinarides, while the reverse Buje Fault, or rather the Buje Thrust Sheet, is part of the Dinaric thrust structure, which became part of the autoch - ton ( sensu lato) in the Neogene-recent pushing and subthrusting phase of the Microadria towards the Dinarides. The Sistiana and Kvarner Faults do not intersect the Dinarides, but only extend to the Istra-Friuli Thrust-Undrerthrust Zone. The Sisti - ana and Kvarner Flexural Zones have developed in their extensions in the Dinarides. The first is sim - pler and weaker, but can be followed on a digital relief model at least 50 km into the Dinarides. The second one is considerably stronger and forms an extensive flexural zone of sigmoidal shape, but its extent in the Dinarides is difficult to determine. According to a rough estimate, it extends at least 70 km to 80 km into the Dinarides. In its exten - sion, the Idrija Fault is not bent in the same way as in the extension of the Sistiana Flexural Zone. Discussion of this issue is beyond the scope of this article; here it is sufficient to explain that the Idri - ja Fault is segmented in the area of the karst fields southeast of Mt. Hrušica and in this sense has not yet been investigated in detail, therefore its trace in Figures 1 and 22 is drawn dashed. The course of the Sistiana Fault in the Gulf of Tri - este is not clear. Carulli (2011, fig. 3) hypothetically stretched it from Sistiana Bay towards the south - west, based on the structural map of the contact be - tween the carbonates and the flysch in the subsea of the Gulf of Trieste, which is based on the geophys - ical profiles. Carulli (2011) was guided by a saddle in the hinge of the Savudrija-Buzet Anticline exten - sion drawn on the structural map. Determination of the Sistiana Flexural Zone in the External Dinarides to 60–56° (Placer et al., 2021b) offered a hypothet - ical possibility that the fault trace runs along the north-western edge of the extension of the Savudri - ja-Buzet Anticline, where Carulli (ib.) assumed the Aquilea Fault. According to this variant, there is a possibility that the Sistiana Fault runs from Sistiana Bay towards the west-southwest to the mentioned edge of the Savudrija-Buzet Anticline and continues along the south-western slope of the Friuli Mesozo- ic Carbonate Platform in the Lignano area. Such an interpretation could also mean that the previously uniform Mesozoic carbonate platform margin was cut along the Sistiana Fault, and its south-south- eastern part was moved together with the Istra block towards the Dinarides. In our opinion, the Aq - uileia Fault does not exist; the structural anomaly on the north-western margin of the Trieste-Komen Anticlinorium, to which Carulli linked the Aquil - eia Fault, is, according to our yet unpublished re- search, similar to the structural anomaly between Dinamski model Na sliki 22 je skicirana strukturna geometrija istrskega bloka in jugozahodni del istrskega po- tisnega območja. Že na prvi pogled je opaziti po - vezavo med avtohtonom ( sensu stricto in sensu lato), torej Mikroadrijo in Dinaridi. Izvorni de - formaciji avtohtona sensu stricto sta le Sesljan- ski in Kvarnerski prelom, oba ležita prečno na Dinaride, medtem ko je Bujski reverzni prelom, oziroma Bujska narivna luska, del dinarske na - rivne zgradbe, ki pa je v fazi neogensko-recen- tnega potiskanja in podrivanja Mikroadrije proti Dinaridom, postala del avtohtona ( sensu lato). Sesljanski in Kvarnerski prelom ne sekata Di - naridov, temveč segata le do istrsko-furlanske narivno-podrivne cone, v Dinaridih sta se v nju- nih podaljških razvili sesljanska in kvarnerska upogibna cona. Prva je enostavnejša in šibkejša, vendar jo je mogoče na digitalnem modelu reliefa slediti vsaj 50 km v notranjost Dinaridov. Druga je bistveno močnejša in tvori obsežno upogibno cono sigmoidalne oblike, ki pa ji je težko določiti doseg v Dinaridih. Po grobi oceni sega vanje vsaj 70 km do 80 km. V njenem podaljšku Idrijski prelom ni upognjen tako kot v podaljšku sesljan - ske upogibne cone. Razprava o tem vprašanju presega okvir tega članka, tu zadostuje pojasni - lo, da je Idrijski prelom na območju kraških polj jugovzhodno od Hrušice segmentiran in v tem smislu še ni detajlno raziskan, zato je njegova trasa na slikah 1 in 22 narisana črtkano. Potek Sesljanskega preloma v Tržaškem zali - vu ni jasen. Carulli (2011, sl. 3) ga je na podlagi strukturne karte stika med karbonati v podla - gi in flišem v podmorju Tržaškega zaliva, ki je bila izdelana s pomočjo geofizikalnih profilov, hipotetično potegnil od Sesljanskega zaliva pro - ti jugozahodu. Za vodilo mu je služilo sedlo v temenu podaljška Savudrijsko-Buzetske antikli - nale, ki se je izrisala na strukturni karti. Potem, ko je bila določena smer sesljanske upogibne cone v Zunanjih Dinaridih, ki znaša okoli 60° do 65° (Placer et al., 2021b), se je ponudila hipo - tetična možnost, da poteka po severozahodnem robu podaljška Savudrijsko-Buzetske antiklina - le, kjer je Carulli (ib.) domneval Oglejski pre - lom. Po tej varianti obstaja možnost, da poteka Sesljanski prelom od Sesljanskega zaliva proti zahodu-jugozahodu do omenjenega roba Savu - drijsko-Buzetske antiklinale in se nadaljuje po jugozahodnem pobočju Furlanske mezozojske karbonatne platforme na območju Lignana (Lignano). Taka interpretacija pa bi lahko tudi pomenila, da je bil ob Sesljanskem prelomu prej enotni rob mezozojske karbonatne platforme 65 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria the Čičarij a and Trieste-Komen Anticlinorium in the Val Glinščica/Rosandra area, only that the Tri - este-Komen Anticlinorium meets a similar unit in the northwest, which is covered by fluvial deposits on the Friuli Plain. If the proposed interpretation of the Sistiana Fault trace turns out to be correct, it could represent the agreed boundary between the Adriatic and Friuli Mesozoic Carbonate Platforms. This assumption is supported by the consistency of the strike-slip direction along the Sistiana Flexural Zone and along the proposed route of the Sistiana Fault. The offset in both cases is left-lateral. The as - sumption that the Sistiana Fault has not been active recently (Placer et al., 2021b) speaks only in favour of the proposed hypothesis. The location of the Kvarner Fault in the Adriat - ic Sea subsea was well determined by Špelić et al. (2021). At the same time, we must draw attention to the subsided block of the Microadria on the east- south-eastern side of the Kvarner Fault, with which the Kvarner islands, belonging to the External Di - naric Imbricated Belt, also subsided and which we have named the Kvarner block. It is the result of the Paleogene and Neogene-recent Microadria activi- ties southeast of the Kvarner Fault, description of which exceeds the scope of this article. The forma - tion of the East Istrian Anticline is also related to this same scheme (Korbar et al., 2020). Formation of the Istra Pushed Area and the two flexural zones is therefore related to the movement of the Istra block towards the Dinarides. The differ - ence in the size of the flexural zones and the sub - marine response of the Sistiana and Kvarner Faults shows that northwest of the Kvarner Fault the Istra block is only the most exposed object of this part of the Microadria, while the second in the series is the Friuli block. The Sistiana Fault is therefore less im - portant than the Kvarner Fault. Based on this, we believe that the Kvarner Fault divides the Microad- ria into the Po and Adriatic segments. This assump - tion is also supported by the fact that southeast of the Kvarner Flexural Zone there is no structure that would surpass it in terms of size and importance, at least in the middle Adriatic area. The Istra block is therefore the most eastward-pushed part of the Po segment of the Microadria. Three dynamic units lie opposite the Dinarides: the Trieste parallelepiped, the North Istra Extru - sion Wedge, and the South Istra Pushed Wedge in the Istra Block. The formation of the Kraški rob - Mt. Hrušica Traverse can be explained by the blocking of the lateral extrusion of the North Is - tra Extrusion Wedge towards the Trieste paral - lelepiped. We assume that the Extrusion Wedge was therefore compressed and acted as a rigid presekan, njegov jugo-jugovzhodni del pa pre- maknjen skupaj z istrskim blokom proti Dina - ridom. Oglejski prelom po našem mnenju ne obstaja, strukturna anomalija na severozaho - dnem obrobju Tržaško-Komenskega antiklino - rija, na katero je Carulli vezal Oglejski prelom, je po naših, vendar še neobjavljenih raziska- vah, podobna strukturni anomaliji med Čiča - rijskim in Tržaško-Komenskim antiklinorijem na območju Glinščice, le da se tu stikata Trža - ško-Komenski antiklinorij in podobna enota na severozahodu, ki pa je prekrita z naplavinami Furlanske nižine. Če se predlagana interpretaci - ja poteka Sesljanskega preloma izkaže za pravil - no, bi ta lahko predstavljal dogovorno mejo med Jadransko in Furlansko mezozojsko karbonatno platformo. V prid tej domnevi govori skladnost smeri zmika ob sesljanski upogibni coni in ob predlagani trasi Sesljanskega preloma. V obeh primerih je levi. Domneva, da Sesljanski prelom recentno ni aktiven (Placer et al., 2021b), govori le v prid predlagane hipoteze. Lego Kvarnerskega preloma v podmorju Ja - dranskega morja so dobro določili Špelić et al. (2021). Ob tem moramo opozoriti na ugreznjeni blok Mikroadrije na vzhodno-jugovzhodni strani Kvarnerskega preloma s katerim so se ugreznili tudi Kvarnerski otoki, ki pripadajo Zunanjedi- narskemu naluskanemu pasu. Poimenovali smo ga kvarnerski blok. Gre za posledico paleogenske in neogensko-recentne dejavnosti Mikroadrije jugovzhodno od Kvarnerskega preloma, katere opis presega okvir tega članka. S tem je povezan tudi nastanek Vzhodnoistrske antiklinale. O tej problematiki so pisali Korbar et al. (2020). Nastanek istrskega potisnega območja in obeh upogibnih con je torej povezan s premikom istr - skega bloka proti Dinaridom. Razlika v velikosti upogibnih con in podmorske odzivnosti Sesljan - skega in Kvarnerskega preloma kaže, da je seve - rozahodno od Kvarnerskega preloma istrski blok le najbolj izpostavljen objekt tega dela Mikroa- drije, drugi v nizu je furlanski blok. Sesljanski prelom je torej manj pomemben od Kvarnerske - ga preloma. Glede na to menimo, da Kvarnerski prelom deli Mikroadrijo na padski in jadranski segment. Tej domnevi ustreza tudi podatek, da jugovzhodno od kvarnerske upogibne cone vsaj v območju srednjega Jadrana ni strukture, ki bi jo prekašala po velikosti in pomenu. Istrski blok je torej najbolj proti vzhodu potisnjeni del padske- ga segmenta Mikroadrije. V istrskem bloku ležijo nasproti Dinaridom tri dinamske enote, tržaški paralelepiped, se - vernoistrski iztisni klin in južnoistrski potisni 66 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK insert between the active Microadria and the pas- sive Dinarides, in which stress state trajectories grew thicker transversely to their direction. Spe - cific deformations occurred in the area of thicken - ing, presented on the correlation diagram in Fig - ure 19. The lateral boundaries of the zones of these deformations are not sharp, but gradually die out more slowly toward the northwest and more quickly toward the southeast. The visible area of influence of the Kraški rob-Mt. Hrušica Traverse is 10 to 15 km wide and about 40 km long. It is necessary to prove the assumption about the formation of the traverse experimentally, and to determine the mutual influence of three factors: the blocking of the North Istra Extrusion Wedge, the Črni Kal Anomaly, and the Senože če Folds Splitting Zone. The presented dynamic model should work from the beginning of the movement of the Microadria towards the Dinarides. More broadly, the process is related to the anticlockwise rotation of the Mi- croadria (Weber et al., 2006), which is expressed in two components, in the hinterland of the Istra block, transpressive and shear (Placer et al., 2010). The question arises as to which status is recently active. Whether it is a transpressive or shear phase could only be determined from focal mechanisms and targeted surface surveys. However, it should be taken into account that one activity does not ex - clude the other, only that one is the prevailing one and the other is parallel, i.e., relieves the burden. It follows from the field data that the role of the Sisti - ana Fault in the recent dynamics is not important (Placer et al., 2021b), but the assumption needs to be proven. The presented dynamic model forms the basis for focused geodetic measurements. The proposed dynamic model is supported by the following structural-geomorphological indi - cators: in the area of the Kraški rob-Mt. Hrušica Traverse, in addition to Mt. Selivec (619 m) and Mt. Vremščica (1027 m), are also the highest peaks of Mt. Nanos (Mt. Suhi vrh 1313 m), the north-west - ern part of Brkini (Mt. Ajdovščina 804 m, Mt. St. Servul 817 m, above Artviže village) and the north-western part of Čičarija (Mt. Slavnik 1028 m). The existence of the South Istra Pushed Wedge is confirmed by the highest peaks of Mt. Učka (Mt. Vojak 1394 m), Čičarija (Mt. Veliki Planik 1272 m, Mt. Gomila 1241 m) and Snežnik hills (Mt. Veliki Snežnik 1796 m). In terms of geomorphology, the Čičarija A n t i c l i n o r i u m g e n e r a l l y r i s e s g r a d u a l l y from the northwest (Mt. Reva by Kozina 587 m) to the southeast (Mt. Veliki Planik). Mt. Slavnik, only some 7 km from Mt. Reva, would therefore be an anomaly if it did not lie in the area of the Kra ški klin. Nastanek traverze Kraški rob - Hrušica je moč razložiti z blokado bočnega izrivanja sever - noistrskega iztisnega klina proti tržaškemu pa - ralelepipedu. Domnevamo, da se je iztisni klin zaradi tega komprimiral in deloval kot trd vložek med aktivno Mikroadrijo in pasivnimi Dinaridi, v katerih so se prečno na njihovo smer zgosti - le trajektorije napetostnega stanja. V območju zgostitve so nastale specifične deformacije, ki so predstavljene na korelacijskem diagramu na sliki 19. Bočne meje območij teh deformacij niso ostre, temveč postopoma zamirajo proti severo - zahodu počasneje in jugovzhodu hitreje. Vidno vplivno območje traverze Kraški rob - Hrušica je široko okoli 10 km do 15 km, v dolžino pa sega okoli 40 km. Domnevo o nastanku traverze je potrebno ek - sperimentalno dokazati, pri tem pa določiti med - sebojne vplive treh dejavnikov: blokade severno- istrskega iztisnega klina, črnokalske anomalije in senožeške cone cepljenja gub. Predstavljeni dinamski model naj bi deloval vse od pričetka pomikanja Mikroadrije proti Dinaridom. Širše je proces povezan z rotacijo Mikroadrije v nasprotni smeri urinega kazalca (Weber et al., 2006), kar se v zaledju istrskega bloka, izraža v dveh komponentah, transpresivni in zmični (Placer et al., 2010). Postavlja se vpra - šanje, katero stanje je recentno dejavno. Ali gre za transpresivno ali zmično fazo bi se dalo ugo - toviti le iz potresnih mehanizmov in z usmerje - nimi površinskimi raziskavami. Treba pa je upo - števati, da ena aktivnost ne izključuje druge, le da je ena glavna, druga pa vzporedna, oziroma razbremenilna. Iz terenskih podatkov izhaja, da vloga Sesljanskega preloma v recentni dinami - ki ni pomembna (Placer et al., 2021b), vendar je potrebno domnevo dokazati. Predstavljeni di - namski model je osnova za usmerjene geodetske meritve. Predlagani dinamski model podpirajo nas - lednji strukturno-geomorfološki kazalci: v ob - močju traverze Kraški rob - Hrušica ležijo po - leg Selivca (619 m) in Vremščice (1027 m), tudi najvišji vrhovi Nanosa (Suhi vrh 1313 m), seve- rozahodnega dela Brkinov (Ajdovščina 804 m, Sv. Servul v Artvižah 817 m) in severozahod - nega dela Čičarije (Slavnik 1028 m). Obstoj juž - noistrskega potisnega klina potrjujejo najvišji vrhovi Učke (Vojak 1394 m), Čičarije (Veliki Planik 1272 m, Gomila 1241 m) in Snežniškega hribovja (Veliki Snežnik 1796 m). Čičarijski an - tiklinorij se v geomorfološkem smislu na sploš - no polagoma dviguje od severozahoda (Reva pri Kozini 587 m) proti jugovzhodu (Veliki 67 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria rob – Mt. Hrušica Traverse. Mt. Veliki Snežnik lies in a structural block that has risen extremely high above the landscape. According to OGK, sheet Il - irska Bistrica, this process was helped along by the appropriate shape of the block, which probably nar- rows in depth in a wedge-shaped manner. In the intermediate space between the Snežnik hills and Čičari ja lies the Brgudsko podolje (plane), a com - pressional trench. A complex view of the geomor - phology of the Istra Pushed Area will be given in the following discussion. The importance and existence of the Črni Kal Anomaly is also reflected in the geomorphology of the Istra Pushed Area, with important structural lines of this zone running parallel to the anoma - ly: the north-eastern boundary of the Istra-Friuli Thrust-Underthrust Zone, the north-western part of the Čičarija Anticlinorium axis, and the north-west - ern part of the Brkini Synclinorium axis. Everything is nicely reflected in the course of the structur- al-geomorphological trajectories between the Sisti - ana and Kvarner Flexural Zones. In this scheme, the unresponsiveness of the Raša Fault stands out in the area of the Kraški rob - Hrušica Traverse, and there are two reasons for this: the Raša Fault was formed at a late stage in the development of the Istra Pushed Area (Placer et al., 2021b), and part of the lateral bending was compensated for by the forma - tion of transpressive Vremščica Anticline. The presented deformation model covers only Istra and its immediate hinterland, i.e. the Istra Block and the area of the External Dinaric Im - bricated Belt between the Sistiana and Kvarner Flexural Zones. The area of the External Dinaric Thrust Belt is not covered in the discussion. Conclusion Istra is part of the Dinaric promontory (Mi - croadria) on which the External Dinarides are thrusted. Thrusting of the Dinarides ended in the middle of Paleogene, and in the middle of Neo - gene, the movement of the Microadria towards the Dinarides began, which continues today. Istra lies in the Istra Block, which moved significant - ly towards the Dinarides between the left-lateral strike-slip Sistiana and right-lateral strike-slip Kvarner Faults. As it moved, it pushed the Dinar - ides in front of it, creating a large-scale arc-like structure called the Istra Pushed Area. Part of the movement of the Microadria to - wards the Dinarides was also compensated by un - derthrusting, which took place and is still active along newly formed reverse faults. Along these, the hanging block was raised, and the Paleogene thrust planes within it were anticlinally folded. The Planik), Slavnik, le okoli 7 km od Reve, bi bil torej anomalija, če ne bi ležal v območju tra - verze Kraški rob - Hrušica. Veliki Snežnik leži v strukturnem bloku, ki se je ekstremno dvig - nil nad pokrajino. Po podatkih OGK, list Ilirska Bistrica, je k temu pripomogla ustrezna oblika bloka, ki se v globino verjetno klinasto zožuje. V vmesnem prostoru med Snežniškim hribov - jem in Čičarijo leži Brgudsko podolje, ki je kom - presijski jarek. Kompleksen pogled na geomor - fologijo istrskega potisnega območja bo podan v naslednji razpravi. Pomen in obstoj črnokalske anomalije se od - raža tudi v geomorfologiji istrskega potisnega območja, vzporedno z anomalijo potekajo po - membne strukturne linije tega območja: seve - rovzhodna meja istrsko-furlanske narivno-pod - rivne cone, severozahodni del osi Čičarijskega antiklinorija in severozahodni del osi Brkin - skega sinklinorija. Vse se lepo odraža v pote - ku strukturno-geomorfoloških trajektorij med sesljansko in kvarnersko upogibno cono. V tej shemi izstopa neodzivnost Raškega preloma v območju traverze Kraški rob - Hrušica, vendar obstajata za to dva razloga, Raški prelom je nas - tal v poznem stadiju razvoja istrskega potisne - ga območja (Placer et al., 2021b), del bočnega upogiba se je kompenziral z nastankom Vremške transpresivne antiklinale. Predstavljeni deformacijski model zajema le Istro in njeno neposredno zaledje, torej istrski blok in območje Zunanjedinarskega naluskane - ga pasu med sesljansko in kvarnersko upogib - no cono. Območje Zunanjedinarskega narivnega pasu v razpravi ni zajeto. Sklep Istra je del dinarskega predgorja (Mikroadri - ja) na katerega so narinjeni Zunanji Dinaridi. Narivanje Dinaridov se je zaključilo sredi pale - ogena, sredi neogena pa se je pričelo premikanje Mikroadrije proti Dinaridom, ki traja še danes. Istra leži v istrskem bloku, ki se je med levozmič - nim Sesljanskim in desnozmičnim Kvarnerskim prelomom, ekstremno premaknil proti Dina - ridom. Med premikanjem je Dinaride potiskal pred seboj, da je nastala obsežna ločna struktura imenovana istrsko potisno območje. Del premikanja Mikroadrije proti Dinaridom se je kompenziral tudi s podrivanjem, to se je dogajalo in se še vedno dogaja, ob novonastalih reverznih prelomih, ob katerih se je krovninsko krilo dvignilo, paleogenske narivne ploskve v njem pa so se antiklinalno usločile. Cona pod - rivanja se v Istri na površju prekriva z mejo 68 Ladislav PLACER, Igor RIŽNAR & Ana NOVAK underthrusting zone in Istra on the surface over- laps with the Dinarides boundary, so it makes sense to speak of a thrust-underthrust zone (Istra-Friuli Thrust-Underthrust Zone). On the surface the Sis - tiana and Kvarner Faults only extend as far as the mentioned thrust-underthrust zone, and further to the northeast they continue under the units of the Dinaric thrust structure, so only the lateral and ver- tical response of the movements along both faults under the thrust units is visible on the surface. In the extension of the Sistiana Fault, a relatively sim - ple Sistiana Flexural Zone was formed, while in the extension of the Kvarner Fault a complicated and far more extensive Kvarner Flexural Zone in the form of a large sigmoid was formed. This lends the Kvar - ner Fault exceptional importance in the breakdown of the Microadria block, which is why we think it divides it into its Po and Adriatic segments. The Istra block is the farthest eastward-pushed part of the Microadria Po segment. The Istra block has a hybrid structure, con - sisting of the autochthonous sensu stricto and the aborted Buje Thrust Sheet, which was part of the Dinarides during the thrusting period and became a connected part of the Microadria (autochthonous sensu lato) during the underthrusting period. The Karški rob – Mt. Hrušica Traverse, which lies in the Istra Pushed Area transversely to the Dinar- ides, was created as a result of the hybrid structure of the Istra block. Its geomorphologically most prominent deformation is Mt. Vremščica. Mt. Vremščica is a transpressive anticline that rose from the levelled karst surface. Its formation is a challenge for the study of the geomorphology of karst areas. The direction of the Sistiana Flexural Zone indicates the course of the Sistiana Fault in the seabed of the Gulf of Trieste from Sistiana to the west-southwest. According to such course, it can be assumed that the external boundary of the Mes - ozoic carbonate platform in the area of Lignano is transversally shifted along the Sistiana Fault. If so, the Sistiana Fault could represent an agreed boundary between the Friuli and Adriatic Meso- zoic Carbonate Platforms. The hydrographic network of Istra is specific and entirely subordinated to the deformations of the South Istra Pushed and North Istra Extrusion Wedges. The Classical Karst (territory between the Gulf of Trieste and the Ljubljana Marshes) lies entirely in the Istra Pushed Area, where the devel- opment of the hydrographic network is mainly re - lated to the deformations of shortening caused by the Neogene to recent movement of Istra towards the Dinarides. Dinaridov, zato je smiselno govoriti o narivno - -podrivni coni (istrsko-furlanska narivno-pod - rivna cona). Sesljanski in Kvarnerski prelom segata na površju le do omenjene narivno-pod - rivne cone, naprej proti severovzhodu pa se na- daljujeta pod enotami dinarske narivne zgradbe, zato je na površju viden le bočni in vertikalni odziv premikov ob obeh prelomih pod narivni - mi enotami. V podaljšku Sesljanskega preloma je nastala razmeroma enostavna sesljanska upo - gibna cona, v podaljšku Kvarnerskega preloma pa komplicirana in po dimenzijah dosti obsež - nejša kvarnerska upogibna cona v obliki velike sigmoide. Ta daje Kvarnerskemu prelomu v blo - kovni razčlenitvi Mikroadrije izjemen pomen, zato menimo, da jo deli na njen padski in jadran - ski segment. Istrski blok je najdlje proti vzhodu potisnjeni del padskega segmenta Mikroadrije Istrski blok ima hibridno zgradbo, sestavljen je iz avtohtona sensu stricto in abortirane Bujske narivne luske, ki je bila v obdobju narivanja del Dinaridov, v obdobju podrivanja pa je posta- la priključeni del Mikroadrije (avtohton sensu lato). Traverza Kraški rob - Hrušica, ki leži v istrskem potisnem območju prečno na Dinari - de, je nastala zaradi hibridne zgradbe istrskega bloka. Njena geomorfološko najbolj izstopajoča deformacija je Vremščica. Vremščica je transpresivna antiklinala, ki se je dvignila iz uravnanega kraškega površja. Njen nastanek je izziv za študij geomorfologije kra - ških območij. Smer sesljanske upogibne cone nakazuje po - tek Sesljanskega preloma v podmorju Tržaške - ga zaliva od Sesljana proti zahodu-jugozahodu. Na podlagi tega je moč domnevati, da je zunanja meja mezozojske karbonatne platforme na ob - močju Legnana (Legnano) prečno premaknjena ob Sesljanskem prelomu. Če je tako, bi Sesljanski prelom lahko predstavljal dogovorno mejo med Furlansko in Jadransko mezozojsko karbonatno platformo. Hidrografska mreža Istre je specifična in povsem podrejena deformacijam južnoistrskega potisnega in severnoistrskega iztisnega klina. Klasični kras (ozemlje med Tržaškim zalivom in Ljubljanskim barjem) leži v celoti v istrskem potisnem območju, kjer je razvoj hidrografske mreže pretežno povezan z deformacijami krčenja prostora, ki jih je izzvalo neogensko do recentno pomikanje Istre proti Dinaridom. 69 Transverse Dinaric zone of increased compression between the Kraški rob and Hrušica Regions, NE Microadria References / Literatura Blašković, I. & Aljanović, B. 1981: Mikrotekton - ski elementi kao osnova za model tektonske građe šireg područja Kvarnera = Microtec - tonic elements as a basis for tectonic model of the broader Kvarner area. Simp. Komplek - sna naftno-geološka problematika podmorja i priobalnih djelova Jadranskog mora, Split, Zbornik radova (Proceedings), 87–100, Za - greb. 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