ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Jahrbuch der Geologischen Bundesanstalt Jahr/Year: 2000 Band/Volume: 142 Autor(en)/Author(s): Pistotnik Julian, Elecko Mihal, Vass Dionyz, Hok Jozef, Vozar Jozef, Nagy Alexander, Sefara Jan, Dudko Antonyina Artikel/Article: Tectonic Map 493-504 ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at Introduction have been connected with the escape of the Megaunit from the Alpine area. The Tectonic Map shows the structure of the area The main features of the present setting of the area including structural elements, tectonic units as well as its were brought about in the Miocene. This period was char- tectonic activity in geological time and the nature of tec- acterised by transtensional basin evolution and calc-alkali tonic movements. The legend of the map was approved by volcanic activity. The most of the interpretable lineaments all partners. are also associated with this period. In the DANREG area the following regional geologi- The process of basin opening in the northern part of the cal units are partly or fully included: Danube Basin (geo- basin had a character of an asymmetric lithospheric exten- graphically subdivided into Kisalföld (Little Hungarian sion (VASS & PERESZLÉNYI 1998). The extension style fits Plain) and Danube Lowland, respectively), Vienna Basin, well with a model of heterogeneous lithospheric stretching Ipel' Basin, Malé Karpaty (Little Carapthian Mts), Dorog (COWARD 1986). and Zsámbék basins, as well as volcanic muntains such ad The southern Danube Basin, Little Hungarian Plain is the Krupinská planina, Visegrád and Börzsöny Mts. considered to be a transtensional basin (HORVÁTH Several tectonic phases and main structural units bear- &ROYDEN 1981) with a pull-apart mechanism of basin ing different structural elements have been distinguished opening (ROYDEN 1988, BALLA 1989a). Such a mechanism in the area. The geological formations were merged corresponds to the synrift phase of basin filling. according to the main phases. A reference number has The Vienna Basin after the end of Alpine thrusting, been assigned to each major tectonic line. from the Karpathian time opened by means of pull-apart mechanism in a palaeostress field with S–N compression. However, the faults responsible for its opening, neither General regional setting of the DANREG area penetrated deeper into the crust, nor did they intersect the crust, respectively (thin-skinned pull-apart; ROYDEN The basement of the Little Hungarian Plain and the 1985). In the Late Miocene to Pliocene transtensional and northern Danube Basin can be subdivided into two major extensional tectonic regime characterised the area. units: the Alpine–Carpathian belt (East Alpine–West The subsidence of the Danube Basin during the Late Carpathian Nappe) in the western and northern parts and Miocene and Pliocene was comparatively passive and is the Pelso Megaunit [in the sense of FÜLÖP et al. 1987, attributed to terminal postrift phase (ROYDEN et al. 1983, FÜLÖP & DANK (ed.) 1986, DANK & FÜLÖP 1990] of the ROYDEN 1988, HORVÁTH 1990, 1993). Transdanubian Range (TR) in the southeastern part. The two units are separated from each other by the Basic tectonic units and structural elements of the Rába–Hurbanovo Fault Zone (VOZÁR 1996) which is an DANREG area important transform fault zone well known from seismic and magnetotelluric measurements. Sopron area The Rába Line traversing the basement of the Little Hungarian Plain and its north-eastern prolongation, the The pre-Cainozoic rocks of the Sopron area belong to Hurbanovo–Diósjenõ Line constitute the main structural the East–Alpine Units. They crop out in the Sopron Hills. boundary between these units. The Grobgneiss Formation and Wechsel series at Recently, the model gained wide-ranging approval Fertõrákos have been submitted to amphibolite facies stressing that the Pelso Unit had acquired its present posi- Variscan regional metamorphism (280–359 Ma, FÜLÖP tion after having been pushed away from the Alpine and 1990). The retrograde greenschist facies metamorphism is Dinaride region during Palaeogene–Early Miocene time assumed to have taken place during the Austrian phase (KÁZMÉR & KOVÁCS 1985, BALLA 1987, 1989a, (92–124 Ma). NAGYMAROSY 1990, CSONTOS et al. 1992, HAAS et al. The pre-Tertiary rocks outcropping in the Sopron 1995). The TR is considered to be a part of the Pelso region reveal a basically SW dipping schistosity. The Megaunit. In this unit are amalgamated lithospheric structural elements indicate a NNW oriented, last-phase blocks escaped from the Central Alps and the NW nappe movement (PAHR 1991). A lineation of similar ori- Dinarides along large strike-slip faults: the sinistral entation (VENDEL 1947, 1981) presents scarce folds (or Rába–Hurbanovo–Diósjenõ (25) bordering the Pelso Unit rather flexures) with variable axis orientation. towards the N and the dextral Balaton Line (behind the One of the elements in the Neogene structure of DANREG area) towards the South. Sopron Hills is the Jávor Basin confined by roughly N–S The sinistral movement of the Pelso Megaunit along striking faults. The faults developed presumably in the the Rába–Hurbanovo–Diósjenõ Line was connected with Sarmatian (Pannonian) period, since a right-handed counter-clockwise block rotation (CCW, BALLA 1985). Pannonian synsedimentary fault of similar strike was iden- Palaeomagnetic investigations indicated that the rotation tified east of the basin (ROSTA 1993, Kõhida Line (34). In took place in two pulses: the first by 50° at the end of the vicinity of Sopron Hills FODOR et al. (1990) recon- Ottnangian, the second by 30° at the end of the Karpathian structed for the Middle Miocene (Sarmatian) – Pliocene age and/or in Early Badenian (MÁRTON et al. 1995, 1996; interval basically the same tensional stress field charac- MÁRTON & MÁRTON 1996). The first stage of rotation may terised by ESE–WNW direction. 495 ©Geol. Bundesanstalt, Wien; download unter www.geologie.ac.at Faults measured in the exposures of the Ligeterdõ Tatricum (sensu ANDRUSOV et al. 1973), which in the Gravel Formation (Ottnangian) are also of roughly N–S DANREG area are subdivided into three groups, the strike. The Sopron Line (32) traverses the Sopron Hills sep- Tribeè, PovaΩsk˝ Inovec and Malé Karpaty Groups. The arating its south-western part from the north-eastern one and lowermost tectonic units in the Danube Basin are the very bordering the Jávor Basin from the south. The Sopron Hills problematic Upper Austroalpine Mihályi Phyllite (corre- themselves are bordered in turn by the Kópháza Line (35) latable with the Graz Palaeozoic) and the southern from the south-east constituting simultaneously the north- Penninicum in the Gabèíkovo Depression (correlated by western boundary of the Nagycenk Basin. We assume that VOZÁR, 1996 with the Kõszeg and Rechnitz areas). they are conjugated faults associated with the formation of The basement of Little Hungarian Plain east of the Miocene basins. Rába Line is build up by rocks belonging to the Transdanubian Range and/or to the Pelso Megaunit (see Danube Basin bellow). Basement of the basin Neogene of the Danube Basin The pre-Neogene basement of the Little Hungarian Plain is composed mostly by metamorphic rocks. The Danube Basin is a thermal extensional basin, The slightly metamorphic schist assemblage in the which began to open at the end of the Early Miocene. The basement of the Mihályi Horst may be subdivided accord- basin is filled mainly by siliciclastics accompanied by ing to BALLA [(ed.) 1993, 1994] into the Vaszar type as an caustobioliths and seldom by organic limestones. The unambiguous equivalent of the Transdanubian Range type main part of the synrifting phase took place during the Palaeozoic. The Mihályi schists are tentatively correlated Middle Miocene (Badenian to Sarmatian). The process of with the Graz Palaeozoic. The Sausal Palaeozoic, or the basin filling was terminated by a postrift phase during the Kõszeg Mesozoic are analogues of the mentioned forma- Late Miocene (Pannonian–Pontian) and Pliocene. tions and/or they are regarded to be of West Carpathian The rifting stage, i.e. initial stage of basinal extension provenience. The Nemeskolta schists may have filled the was not uniform throughout the whole basin. Fault-con- dislocation zone associated with the Rába Line and might trolled initial synrift subsidence was more intensive in the as well be made up by rocks of varied origin. outer zone of extension at the northern margin of the basin In the basement of the western part of the Little (in the Blatné, Rinovce, Komjatice and ≥eliezovce de- Hungarian Plain seismic profiles POGÁCSÁS et al. (1991) pressions) than in the internal zone of extension delineated four, roughly N–S striking nappe boundaries on (Gabèíkovo depression) north of the Danube River. the basis of seismic profiles. One of them dips towards SE, The postrift sediments (Pannonian to Pliocene) in the E while the other three towards W, WNW. The E, SE dip- northern part of the Danube Basin are distributed in an ping plane represents the northern prolongation of the opposite way compared to the synrift ones. The maximum nappe boundary traversing the eastern side of the Kõszeg thickness of postrift sediments occurs in the internal zone Penninicum. The second one passes close to the axis line close to the Danube River (surroundings of the town of Csapod Basin, whereas the third and fourth ones can be Dunajská Streda). The postrift sediments in the outer zone traced in the western and eastern limbs of the Mihályi of the basin are considerably thinner. The postrift sedi- Horst, respectively. BALLA (1994) suggests that the nappes ments are only in some cases disrupted by faults. dipping opposite one against the other constitute a synform During the Badenian the tectonic development in the structure between the northern prolongation of the Kõszeg area of the Danube Basin was under the control of the Hills and the Mihályi Horst.