Regional Geology Reviews Geology of Hungary Alter und Altern: Wirklichkeiten und Deutungen Bearbeitet von Janós Haas 1. Auflage 2012. Buch. xxii, 246 S. Hardcover ISBN 978 3 642 21909 2 Format (B x L): 17,8 x 25,4 cm Weitere Fachgebiete > Geologie, Geographie, Klima, Umwelt > Geologie > Geologie: Allgemeines Zu Inhaltsverzeichnis schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. Geology and History of Evolution of the Tisza Mega-Unit 2 Tibor Szederke´nyi, Ja´nos Haas, Andra´s Nagymarosy, and Ge´za Ha´mor The Tisza Mega-unit (Tisia Terrane) forms the On the basis of these features both pre-Mesozoic basement of the Pannonian Basin south of the and Mesozoic sequences are classified into Mid-Hungarian Lineament (see Fig. 1 in “Intro- numerous units and subunits. The pre-Mesozoic duction”). In the territory of Hungary the pre- (Variscan) basement of the Tisza Mega-unit is Neogene basement crops out only in two relatively actually a composite terrane which was accreted small, isolated areas in South Transdanubia – the during the Variscan Orogeny. During the Alpine Mecsek Mountains and Villa´ny Hills (Figs. 1, 2 in cycle true terrane dispersion did not occur, but “Introduction”). However, more than 3,000 wells, facies zones were differentiated in the Jurassic oil and uranium prospecting boreholes provide and nappe-systems were formed in the Creta- information on the geologic features of the base- ceous. ment and the younger overburden of the basins. Significant parts of the Tisza Mega-unit extend into Croatian (Slavonian), Serbian (North Vojvo- 2.1 Pre-Variscan to Variscan dina) and Romanian (West Transylvanian) terri- Evolution tories (Szederke´nyi 1974, 1984; Kova´cs 1982; Ful€ op€ 1994; Kova´cs et al. 2000). In Romania and The Tisza Mega-unit is a Variscan orogenic col- Croatia large mountains and uplands (Apuseni lage which was accreted during the Carboniferous– Mts., Papuk Mts., Psunj Mts.) provide an excellent Permian, becoming part of the European continent. opportunity to study its structural setting and stra- However, at present the boundaries of the Tisza tigraphy. Mega-unit are determined by the Alpine structural The Tisza Mega-unit forms a more than evolution (Fig. 1 in “Introduction”, 1.1). Its north- 100,000 km2-large lithosphere fragment broken western boundary is the Mid-Hungarian Linea- off of the southern margin of Variscan Europe ment (Szepesha´zy 1975; in the earlier literature: during the Jurassic (Bathonian), and after com- Zagreb–Kulcs–Herna´d Lineament: Wein 1969; plicated drifting and rotational processes it occu- Zagreb–Zemplin Lineament: Grecula and Varga pied its present-day setting in the Pannonian 1979). It is overthrust southwestward onto the Basin during the Early Miocene (Balla 1986; ophiolite-bearing Sava Zone (in sense of Schmid Csontos et al. 1992; Horva´th 1993). The crystal- et al. 2008; Ustaszewski et al. 2008). Overthusts of line basement and the overlying Upper Palaeo- the Vardar and Mures (Trasylvanian) ophiolite zoic and Mesozoic overstep sequences show belts mark the southern and southeastern boundary heterogeneous lithology and lithostratigraphy, of the Tisza Mega-unit (Sa˘ndulescu et al. 1981; indicating various phases of geologic evolution. Csontos and Vor€ os€ 2004; Schmid et al. 2008). J. Haas (ed.), Geology of Hungary, Regional Geology Reviews, 103 DOI 10.1007/978-3-642-21910-8_2, # Springer-Verlag Berlin Heidelberg 2012 104 2 Geology and History of Evolution of the Tisza Mega-Unit Fig. 2.1 Pre-Alpine structural units of the Tisza Mega-unit (After Szederke´nyi 1997. The northeastern border is provided by the North fracture zones. The units can be subdivided into Transylvanian or Somes Line. subunits bounded by fracture zones of secondary The name “Tisza Mega-unit” is derived from importance. Thus, all units and subunits have the term Tisia, of the so-called “median-mass con- tectonically determined extensions and bound- cept” which arose at the beginning of the aries and show characteristic lithostratigraphic twentieth century in the Hungarian geology columns and evolution. (Prinz 1914, 1923, 1926;Lo´czy 1918;Kober The pre-Alpine units (terranes) and the sub- 1921). A common feature of these hypotheses units constituting them are as follows (Kova´cs was the assumption of an old (Palaeozoic or et al. 2000; Fig. 2.1): older) and rigid crystalline central massif which – Slavonia–Drava Unit (Terrane) much as a rigid boot-stretcher – strained the Car- Babo´csa Subunit pathians during their uplifting. The name of this Baksa Subunit hypothetical ancient core-massif was Tisia, named Kunsa´g Unit (Terrane) after the Tisza River by Prinz (1914). Today it is Mo´ra´gy Subunit plausible that the basement of the Pannonian Basin Ko˝ros€ Subunit is not a rigid crystalline massif. However, the old Be´ke´s Unit (Terrane) name has been preserved, although in a sense Kelebia Subunit significantly different from the original one. Csongra´d Subunit Battonya Subunit Sarkadkeresztu´r Subunit 2.1.1 Crystalline Complexes In addition to the large units (terranes) listed above, several small units (“outliers” – nappe Within the crystalline basement of the Tisza remnants, tectonic wedges) are also found in the Mega-unit, three units (terranes) have been dis- Tisza Mega-unit which show entirely different tinguished, separated from each other by major lithological and metamorphic features than 2.1 Pre-Variscan to Variscan Evolution 105 those of large terranes. They are: Horva´therte- – Pre-Variscan deformation has only been lend Unit, Szalatnak Unit, O´ falu Unit, Ta´zla´r ´ detected in the “parautochthonous” units; Unit, Almosd Unit. – Variscan late kinematic heating (with andalusite mineralisation) occurs primarily in the nappe units; 2.1.2 Lithostratigraphy of the – Late Cretaceous contact metamorphism Tectono-stratigraphic Units and belonging to the banatitic intrusions in the Tectono-metamorphic Evolution Hungarian part of the Tisza Mega-unit only occurs in the nappe units. Conventional stratigraphic methods cannot be applied in the metamorphic complexes because 2.1.2.1 Slavonia–Drava Unit the original features of the rocks are largely or The Slavonia–Drava Unit is located in southeast- totally destroyed, and boundaries of metamor- ern Transdanubia, extending southward into east- phic units generally cut across those of the pre- ern Croatia. It is bordered by the Mid–Hungarian metamorphic lithological units. The basement of Lineament to the northwest and by the Mecse- the Tisza Mega-unit is affected, in the over- kalja Fracture Zone to the east. No outcrops of whelming majority of cases, by medium to this terrane are found in Hungarian territory, but high-grade metamorphism, as a result of which there are some in the Papuk and Psunj Mts. in the former units have been amalgamated. Conse- Croatia. A general NW-SE-striking of forma- quently, new lithological units were developed, tions is characteristic all over the Slavonia- with new borders and a new metamorphic age Dravia Terrane, underscoring its relationship to reflecting the age of last heating. the East Croatian crystalline basement. The lithostratigraphic chart (Fig. 2.2) displays both metamorphic features and the tectono-meta- morphic history of the rock columns. The col- Babo´csa Complex umns indicate the time-range of the protolith This complex makes up the northwestern part of accumulation. Top of the columns shows the the Slavonia–Drava Unit. It consists mostly of timing of the last progressive metamorphic medium-grade gneiss with subordinate micas- event. The outliers (nappe remnants and tectonic chist and amphibolite intercalations. Apart from wedges) either “hang in space” in the lithostrati- an uncertain Caledonian measurement (Jantsky graphic table (because their parent complexes are 1979) a double Variscan metamorphism has been unknown), or within the rock column of the host established. The first phase is represented by a unit. Barrow-type deformation with 6–9 kbar pressure Subunits of the Slavonia–Drava and Kunsa´g and 17–27 C/km thermal gradients; the second is Unit are relatively autochthonous (“parau- an andalusitic, higher-temperature phase (34 C/km ´ € € tochthonous”) compared to those of Be´ke´s Unit, thermal gradients – Arkai 1984;Torok 1989). representing the crystalline basement of an On the SE part of the complex the crystalline Alpine nappe-system. rocks are overlain by Upper Carboniferous The lateral relationships of metamorphic lithos- molasse. tratigraphic units are clearly expressed in the gen- eral similarity of protoliths and metamorphic Baksa Complex character as well as in time of culmination of This unit makes up the crystalline basement of metamorphic phases, which are accompanied by Villa´ny Hills and its northern foreland up to the migmatisation and palingenesis. Apart from the Mecsek Mts. Its southwestern border is a fracture outliers there are some essential differences zone (transcurrent fault) running between the between the two main groups of lithostratigraphic Kunsa´g and Slavonia–Drava Units (Kassai 1977). charts. They are manifested in the following Petrographically this complex consists of points: weakly-folded migmatite, gneiss, micaschist, 106