GEOLOGIJA 39, 283-287 (1996), Ljubljana_283
O premiku ob Savskem prelomu
Displacement along the Sava fault
Ladislav Placer
Geološki zavod Ljubljana
Inštitut za geologijo, geotehniko in geofiziko
Dimičeva 14, 1000 Ljubljana, Slovenija
Ključne besede: Periadriatski lineament. Savski prelom, Slovenija
Key-words: Periadriatic lineament, Sava fault, Slovenia
Kratka vsebina
Potrjena je domneva, da je Celjski prelom vzhodni podaljšek Savskega prelo-
ma, iz česar izvira hipotetična podmena, da so oligocenske plasti Radovljiške kot-
line, v kateri je andezitni tuf, odrezani in premaknjeni del oligocenskih plasti in
enakega tufa iz Celjske kotline. Na podlagi tega je določen hipotetični premik ob
Savskem prelomu 65-70 km. Savski prelom je najjužnejši od spremljajočih prelo-
mov Periadriatskega lineamenta.
Abstract
The presumption on the Celje fault being the eastern prolongation of Sava
fault was confirmed. Therefrom arises the hypothesis that the Oligocene beds in
the Radovljica basin in which andesitic tuff occure are a dislocated part of the are
Oligocene marine clay and the corresponding tuff from the Celje basin. On this
basis the displacement of 65-70 km along Sava fault was estirmated. The Sava
fault is the southernmost fault of the Periadriatic lineament zone in the wider
sense.
Savski prelom v Južnih Alpah je odkril Teller (1896), širše ga je pod tem imenom
predstavil Kossmat (1913, 109-110). Potekal naj bi na meji med Karnijskimi Alpa-
mi, Karavankami in Kamniško-Savinjskimi Alpami na severu ter Julijskimi Alpami
in Vzhodnimi Posavskimi gubami na jugu. V Zgornjesavski dolini naj bi bila prelom-
na ploskev strma, na vzhodu pa položna; ob njej naj bi bile Kamniško-Savinjske Alpe
narinjene proti jugu na Vzhodne Posavske gube.
Savski prelom kot strm desnozmični prelom na celotni dolžini sta v skladu s
tedanjimi spoznanji med prvimi obravnavala Hinterlechner-Ravnik in Ple-
ničar (1967, 224) in na podlagi vzporejanja andezitnega tufa v oligocenski morski
glini Radovljiške kotline z enakim tufom v Kamniško-Savinjskih Alpah sklepala na
284
Ladislav Placer
premik ob njem do 25 km. Vendar iz njunega članka ni razvidno, do kod proti vzhodu
naj bi segal Savski prelom. V tem smislu je zanimiva interpretacija Savskega preloma
na karti strukturnega modela Italije (Bigi et al., 1990), kjer je kot vzhodni podaljšek
Savskega preloma obravnavan Libojski ali Marijareški prelom (Buser, 1978, 1979) v
Motniški sinklinali.
Podrobne raziskave zadnjih let v Posavskih gubah so pokazale, da je vzhodni
podaljšek Savskega preloma t.i. Celjski prelom z listov Ljubljana (Premru, 1983a,
1983b) in Celje (Buser, 1978, 1979) na južnem obrobju Celjske kotline. To misel so
uveljavili Kazmer s sodelavci (1996) inFodor s sodelavci (1996, Sava-Celje fault).
Po našem sega Savski prelom od Karnijskih Alp do stika s Šoštanjskim prelomom in
še naprej proti vzhodu (si. 1) in tvori pravzaprav najjužnejšega od spremljajočih
prelomov Periadriatskega lineamenta.
SI. 1. Potek Savskega preloma
1 Kvartar; 2 Oligocenski andezitni tuf; 3 Terciarne in starejše kamnine; 4 Periadriatski linea-
ment; 5 Prelom; 6 Savski prelom prekrit z narivnimi grudami; 7 Savski prelom v narivni grudi; 8
Slabo viden Savski prelom na Osnovni geološki karti 1:100.000; 9 Narivna ploskev; 10 Območje
Radovljiške in Celjske kotline z oligocenskimi plastmi znatne debeline
Fig. 1. Line of the Sava fault
1 Quaternary; 2 Oligocene andezite tuff; 3 Tertiary and older rocks; 4 Periadriatic lineament; 5
Fault; 6 Sava fault overlaied with thrust sheets; 7 Sava fault within the thrust sheet; 8 Poorly
visible Sava fault in the Geological map 1:100.000; 9 Thrust plane; 10 Radovljica and Celje
basin area with the Oligocene beds of considerable thicknes
Savski prelom je nastal kot desnozmični prelom, nato se je zaradi spremembe
globalne geometrije, kar bomo obravnavali v posebni razpravi, spremenilo napetost-
no stanje. Trajektorije največje normalne napetosti so se tedaj postavile približno
pravokotno na smer preloma in v tistih delih, kjer se ob njem stikajo kompetentne in
nekompetentne kamnine, so se prve narinile na slednje. Tako so se Kamniško-Savin-
jske Alpe iz karbonatnih kamnin narinile na severovzhodni rob Radovljiške in Ljub-
ljanske kotline ter na zahodni del Vzhodnih Posavskih gub. Nanje se je narinila tudi
Menina planina. Omenjeno narivanje ni enotno, vendar narivne grude skoraj povsod
prekrivajo glavno prelomno ploskev Savskega preloma. Tam, kjer je ta vidna, npr na
južnem robu Celjske kotline, pa je presekana z zmičnimi prelomi (Buser, 1978), kar
tudi kaže na spremembo napetostnega stanja. Prelom med Kokro in Županjimi Nji-
vami je segment Savskega preloma v narivni grudi. Narivanje Kamniško-Savinjskih
Displacement along the Sava fault_285
Alp prek Savskega preloma so opazili tudi avtorji strukturnega modela Italije. Po-
vsem razumljivo je, da tega nari vanj a ne moremo enačiti s krovnimi nari vi Kamni-
ško-Savinjskih Alp.
Domnevna velikost desnozmičnega premika ob Savskem prelomu temelji na že
omenjeni konstrukciji Hinterlechner-Ravnikove in Pleničarja, le da je mogoče z zdru-
žitvijo prvotnega Savskega preloma in Celjskega preloma v enotni Savski prelom bolj
logično razmišljati o tem vprašanju. Ka z mer in sodelavci (1996) ugotavljajo premik
40 km, in sicer na podlagi razdalje med zahodnima robovoma Radovljiške kotline in
Smrekovškega oligocenskega bazena, vendar se zdi sprejemljivo tudi vzporejanje
oligocenskih plasti osrednjega dela Radovljiške in Celjske kotline, kjer so le-te v obeh
primerih izjemno debele. Premik, konstruiran po tem načelu, znaša okoli 65-70 km
(si. 1). Vse tri variante (25, 40, 65-70 km) so hipotetične in jih je treba preveriti z na-
drobnimi raziskavami.
Ob tej priliki je pomembno omeniti opazko Ampfererja (1917, 419), da so v eni
od prelomnih ploskev prelomne cone Savskega preloma (terminologija v današnjem
smislu) pri Mostah vidne vertikalne drse. Le-te bi lahko kazale na drugo fazo geneze
Savskega preloma.
Desni premik ob Savskem prelomu se je moral zgoditi po oligocenski dobi, morda
celo po miocenski, narivanje ob njem pa je povezano z neotektonsko aktivnostjo.
Razlaga Savskega preloma v novem smislu se ujema z ugotovitvijo Jelena s
sodelavci (1992) o razliki v razvoju terciarnih plasti v severnem in južnem krilu Celj-
skega preloma, ne potrjuje pa mnenja Buser j a (1978, 1979), da poteka Savski
prelom diagonalno prek Vzhodnih Posavskih gub, saj je premik ob prelomu mimo
Zagorja ob Savi, ki ga Buser imenuje Savski, neznaten in ni v skladu s premikom v
Zgornjesavski dolini.
Displacement along the Sava fault
The Sava fault in the Southern Alps v^as discovered by Teller (1896), and intro-
duced under that name by Kossmat (1913, 109-110). Its position is supposed to be
at the boundary between the Karnian Alps, Karavanke and Savinja Alps in the
north, and the Julian Alps and Eastern Sava folds in the south. In the Upper Sava
valley the fault plane is reportedly steep and in the east it is gentle. Along it the Sav-
inja Alps v^ere thrust southv^ards over the Eastern Sava folds.
The Sava fault was considered a steep dextral fault in its entire length accord-
ingly with the concepts of those times among the first byHinterlechner-Rav-
nik & Pleničar (1967, 224). Based on the comparison of the andesitic tuff in
Oligocene marine clay of the Radovljica basin with similar tuff in the Savinja Alps
they estimated the displacement along it to be at most 25 km. In their paper the east-
ward extension of the Sava fault is not clearly defined. Interesting from this aspect is
the interpretation of the Sava fault in the map of the structural model of Italy (Bigi
et al., 1990) on which the Liboje or Marija Reka fault in the Motnik syncline is con-
sidered as the eastern extension of the Sava fault (B us er, 1978, 1979).
Recent detailed investigations in the Sava folds have shown that the eastern
extension of the Sava fault is the so-called Celje fault of the sheets of geological map
1:100.000 Ljubljana (P r e m r u, 1983a, 1983b) and Celje (Buser, 1978, 1979) in the
south borderland of the Celje basin. This concept was asserted by Ka z mer et al.
(1996) and Fodor et al. (1996, Sava-Celje fault). In this new sense the Sava fault
286_Ladislav Placer
should extend from the Karnian Alps to the contact with the Šoštanj fault, and far-
ther eastward (fig. 1), and it should represent actually the southernmost among the
accompanying faults of the Periadriatic lineament.
The Sava fault was initially formed as a dextral, after which the tension state
changed owing to a change of the global geometry. This should be discussed in a sep-
arate paper. The trajectories of the highest normal tension were then directed aproxi-
mately perpedicular to the fault direction. In those parts in which along the fault
competent and incompetent rocks came in contact, the first were thrust over the lat-
ter In this way the Savinja Alps that consist of the carbonate rocks were thrust over
the northeast part of the Radovljica and Ljubljana basins and over the west part of
the Eastern Sava folds. On the latter also Menina planina was overthrusted. The dis-
cussed thrusting was not uniform, but the thrusted units almost everywhere cover
the main fault plane of the Sava fault. In places where it can be observed, as in the
southern rim of the Celje basin, the fault plane is cut by strike-slip faults (Buser,
1978), which is also an illustration of the change of the tension state. The fault
between Kokra and Županje Njive is a segment of the Sava fault in a thrust nappe.
Of the existence of thrusting of the Savinja Alps over the Sava fault became aware
also the authors of the structural model of Italy. It is entirely clear, however, that this
thrusting cannot be equated with the nappes of the Savinja Alps.
The supposed size of the dextral displacement along the Sava fault is based on the
mentioned construction of Hinterlechner-Ravnik and Pleničar The combining of the
original Sava fault and the Celje fault into a unique Sava fault made possible a more
logical reasoning about this problem. Kazmer et al. (1996) report a displacement of
40 km, as based on the distance between the west rims of the Radovljica basin and
the Smrekovec Oligocene basin. Acceptable appears also comparing of Oligocene
beds of the central parts of the Radovljica and Celje basins, where they are in both
circumstances of impressive thickness. The displacement as estimated according to
this principle amounts to about 65-70 km (fig. 1). All three variants (25, 40, 65-70
km) are hypothetic, and their reality should be verified through detailed investiga-
tions.
Here the remark byAmpferer(1917, 419) should be mentioned on the existence
of vertical striations in one of fault planes of the dislocation zone of the Sava fault
(according to the present terminology). These grooves might be indications of the sec-
ond stage of Sava fault evolution.
The right slip along the Sava fault must have occurred in the post-Oligocene, pos-
sibly even post-Miocene times, while the overthrusting along it might be associated
with neotectonics. The interpretation of the Sava fault in the new sense is conform-
ing with the statement of J el en et al. (1992) on the difference of development of Ter-
tiary beds between the north and south flanks of the Celje fault. This, however, does
not confirm Buser's (1978, 1979) opinion on the trace of the Sava fault crossing
diagonally the Eastern Sava folds, since the displacement along the fault at Zagorje
ob Savi, named the Sava fault by Buser, is insignificant, and is not in accordance
with the displacement that was established in the Upper Sava valley.
o premiku ob Savskem prelomu___287
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