1661-8726/08/01S273-22 Swiss J. Geosci. 101 (2008) Supplement 1, S273–S294 DOI 10.1007/s00015-008-1288-7 Birkhäuser Verlag, Basel, 2008 A map-view restoration of the Alpine-Carpathian-Dinaridic system for the Early Miocene KAMIL USTASZEWSKI 1, *, STEFAN M. SCHMID1, BERNHARD FÜGENSCHUH 1, 2, MATTHIAS TISCHLER 1, **, EDUARD KISSLING 3 & WIM SPAKMAN 4 Key words: Tectonics, kinematics, palinspastic restoration, Alps, Carpathians, Dinarides, Adriatic plate ABSTRACT A map-view palinspastic restoration of tectonic units in the Alps, Carpath- (4) The external Dinarides experienced Neogene shortening of over 200 km ians and Dinarides reveals the plate tectonic configuration before the onset in the south, contemporaneous with dextral wrench movements in the internal of Miocene to recent deformations. Estimates of shortening and extension Dinarides and the easterly adjacent Carpatho-Balkan orogen. (5) N–S conver- from the entire orogenic system allow for a semi-quantitative restoration of gence between the European and Adriatic plates amounts to some 200 km at a translations and rotations of tectonic units during the last 20 Ma. Our res- longitude of 14° E, in line with post-20 Ma subduction of Adriatic lithosphere toration yielded the following results: (1) The Balaton Fault and its eastern underneath the Eastern Alps, corroborating the discussion of results based on extension along the northern margin of the Mid-Hungarian Fault Zone align high-resolution teleseismic tomography. with the Periadriatic Fault, a geometry that allows for the eastward lateral The displacement of the Adriatic Plate indenter led to a change in subduc- extrusion of the Alpine-Carpathian-Pannonian (ALCAPA) Mega-Unit. The tion polarity along a transect through the easternmost Alps and to substantial Mid-Hungarian Fault Zone accommodated simultaneous strike-perpendicu- Neogene shortening in the eastern Southern Alps and external Dinarides. lar shortening and strike-slip movements, concomitant with strike-parallel ex- While we confirm that slab-pull and rollback of oceanic lithosphere subducted tension. (2) The Mid-Hungarian Fault Zone is also the locus of a former plate beneath the Carpathians triggered back-arc extension in the Pannonian Basin boundary transforming opposed subduction polarities between Alps (includ- and much of the concomitant folding and thrusting in the Carpathians, we ing Western Carpathians) and Dinarides. (3) The ALCAPA Mega-Unit was propose that the rotational displacement of this indenter provided a second affected by 290 km extension and fits into an area W of present-day Budapest important driving force for the severe Neogene modifications of the Alpine- in its restored position, while the Tisza-Dacia Mega-Unit was affected by up Carpathian-Dinaridic orogenic system. to 180 km extension during its emplacement into the Carpathian embayment. 1. Introduction polarity (Schmid et al. 2008): in the Western and Eastern Alps as well as in the Carpathians thrusts face the European fore- 1.1 Plate tectonic setting land, whereas in the Southern Alps and the Dinarides thrusts face the Adriatic foreland. In a pioneering article, Laubscher The Alps, Carpathians and Dinarides form a topographically (1971) suggested that the Alps and the Dinarides owe their continuous, yet highly curved orogenic belt, which bifurcates different structural facing to opposing subduction polarities. and encircles the Pannonian Basin. They are part of the much Deep reflection seismic profiling and seismic tomography have larger system of Circum-Mediterranean orogens (Fig. 1). De- since shown that the western and central segments of the Alps spite such a continuous topographic expression, this orogenic are underlain by a south-dipping lithospheric slab, attributed system is characterised by dramatically diachronous deforma- to subducted European lower lithosphere (Schmid et al. 1996, tion stages along-strike. Its various parts comprise different 2004a; Schmid & Kissling 2000), whereas the Dinarides and paleogeographic domains, and major thrusts have opposing Hellenides are underlain by a northeast-dipping lithospheric 1 Institute of Geology and Palaeontology, Bernoullistrasse 32, University of Basel, CH-4056 Basel. 2 Institute of Geology and Palaeontology, University of Innsbruck, A-6020 Innsbruck. 3 Institute of Geophysics, ETH Hönggerberg, CH-8093 Zürich, Switzerland. 4 Faculty of Geosciences, Utrecht University, NL-3508 Utrecht, Netherlands. *Corresponding author, now at: Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 Taiwan. E-mail: [email protected], Tel: +886-2-2363 6450 #205 **Now at: StatoilHydro ASA, 4035 Stavanger, Norway. Restoration Alpine-Carpathian-Dinaridic system S273 slab (e.g. Wortel & Spakman 2000; Piromallo & Morelli 2003) In this contribution we present in map-view a palinspastic res- south of 44° N. toration of the substantial displacements and rotations the vari- Recent studies suggest that a northeast-dipping “Adriatic” ous tectonic mega-units of the Alpine-Carpathian-Dinaridic oro- lithospheric slab of about 200 km length also underlies the genic system underwent during the last 20 Ma (e.g. Balla 1987), Eastern Alps in the area east of the Giudicarie and Brenner providing better insight into their early Neogene configuration. Fault (Lippitsch et al. 2003; Kissling et al. 2006). Schmid et al. We propose that the Mid-Hungarian Fault Zone (Fig. 2) origi- (2004b) and Kissling et al. (2006) tentatively proposed that nated from a transform fault, across which the subduction polarity this slab is a remnant of Palaeogene orogeny in the Dinarides, changed from the Alpine to the Dinaridic polarity. Furthermore, which impinged onto the Alps during the Neogene by a combi- our restoration implies c. 200 km of N–S shortening between the nation of northward motion of the Adriatic plate indenter and Adriatic and European plates, in line with the estimated length dextral wrench movement along the Periadriatic Fault. This of the northeast-dipping slab (Lippitsch et al. 2003). This suggests was a speculative assignment, however, since there is no geo- that this slab represents Adriatic lithosphere that was subducted physical evidence for a continuous, northeast-dipping Adriatic since the early Neogene. Based on this interpretation, we discuss lithospheric slab between the Eastern Alps and the Dinarides possible reasons for the current discontinuity of the northeast- north of 44° N (Piromallo & Morelli 2003; this study). dipping slab between the Eastern Alps and the Dinarides. 10°W 0° 10°E 20°E 30°E 40°E range of Fig. 2 E u r o p e a n P l a t e a r p 50°N C a E a s t E u r o p e a n 50°N t h p l a t f o r m i a n Atlantic p s s l Ocean C 45°N A D 45°N in a a r A ri p G p d a Black Sea rea e e th Ca ter n s o uca P n - -Bal su yre in H kan s ne e es s e Pon l ti l de e s 40°N n 40°N Tyrrhenian i d B cs Sea e it ti s li Be s- Za Taurides gr a os an Se Albor 35°N 35°N t l u s a Atla F A r a b i a n h a Hig e P l a t e S 30°N d 30°N km a A f r i c a n P l a t e e 0 250 500 1000 1500 D 10°W 0° 10°E 20°E 30°E 40°E strike-slip or transfer fault oceanic sutures deformation front (outcropping / subsurface) Alpine Tethys active subduction front Alpine Tethys - Neotethys junction subduction polarity Neotethys Fig. 1. Overview of the circum-Mediterranean orogenic belt with the positions of present-day deformation fronts and subduction zones (modified after Cavazza et al. 2004). Traces of oceanic sutures in the Eastern Mediterranean are modified after Stampfli & Borel (2004), in the Alps, Carpathians and Dinarides after Schmid et al. (2004b, 2008), in the Pyrenees after Dewey et al. (1973). Topography and bathymetry are from the ETOPO5 dataset (NOAA, 1988). Continental shelf areas are light grey (less than 2000 m water depth); areas of thinned continental or oceanic crust are dark grey (greater than 2000 m water depth). Subduc- tion polarities are only shown for the range of Fig. 2. S274 K. Ustaszewski et al. 43° a Neotethys e ethys ethys - T T ck S Alpine Alpine Neotethys junction la B isza Mega-Unit Platform T Dacia Mega-Unit Prebalkan, Danubian, Helvetic, Brianconnais Inner Balkanides ardar ophiolites East European ardar ophiolites V V estern Burgas Bacau W 10 a t alais, Rhenodanubian, r p h i a a n s 130 Ceahlau-Severin V Magura Pieniny Klippen Belt Piemont-Liguria, Kriscevo, Szolnok, Sava obducted & Meliata obducted Eastern t C Cernovcy a s Bucharesti E s n a i 10 s h t 133 Pitesti a Ophiolites, suture zones, oceanic accretionary prisms p r ienide a P Basin C Moesian Platform h ransylvanian t T u o Cluj S Sofia 80 80 11 s 65 150 150 T n i m o k 10 F . 130 a F u i C J e r - n i a 180 h 180 an C Balk t arpatho- Skopje n a Kosice n Debrecen p Mts. Bükk e r a s i Beograd on 9 a 9 . B F t Z >180 >180 a n n o n i a Krakow C aul P Darno e F t 50 50 o n Z s Budapest e a v a S W Mid-Hungarian Bratislava C 8 8 Sarajevo E . F Dubrovnik RR 80±10 ien 80±10 n . W F compiled (source given in superscript, see caption) . o F t a b a c a l a Medvednica Mts. R 40 a v 3 o B l ar - Zagreb S p l it-K 3 shortening extension strike-slip extension, this study Massiv 64 3 .