Mesozoic evolution of the Tisza Mega-unit

Abstract

The south-eastern part of the basement of the Pannonian Basin is made up of Variscan crystalline complexes and early Mesozoic formations showing striking affinity with the corresponding formations in the southern margin of the European Plate. This large composite structural unit, which is actually an exotic terrane of European Plate origin, has been named the Tisza Mega-unit. Based upon relevant data of the pre-Tertiary basement of southern Hungary the reconstruction of the position of the Tisza Terrane in the early Alpine evolutionary stages, the process of its separation and break-off from the European Plate, and results of its Eo-Alpine deformations are summarised in the present paper. In the Variscan and early Alpine evolutionary stages the area of the later Tisza Mega-unit was located at the margin of the European Plate. During Variscan orogeny terrane accretion led to intensive deformation and metamorphism in this belt. This was followed by transpressional tectonics and the development of molasse basins in the late and post-Variscan stages, and passive margin evolution after the Neotethys opening in the Middle Triassic. The separation of the Tisza Mega-unit began with incipient continental rifting along the axis of the later Ligurian-Penninic-Vahic oceanic branch in the Late Triassic. The end of terrigenous material deposition in the most external zones, and a coeval change in fossil assemblage, point to the separation of the Tisza Block from the European Plate in the Early Bathonian. Significant rotation of the Tisza Mega-unit and coeval paroxysm of alkaline rift-type basalt volcanism took place in the Early Cretaceous. In the mid-Cretaceous, due to the northward motion of the Adria Block and the related closure of the westernmost Neotethys basin, the extensional regime changed to a compressional one, leading to onset of the nappe stacking and low-grade regional metamorphism within the Tisza microplate. In the foreland of the nappe systems flexural basins came into existence that are characterised by flysch-type sedimentation. In the Early Tertiary the northeastward motion of the Alcapa and Tisza + Dacia Blocks led to the formation of the present-day heterogeneous basement of the Pannonian Basin.

„Oázis a sivatagban” — különösen gazdag ősmaradvány-együttes a fosszíliaszegény üllési Szegedi Dolomitból

“…A középső-anisusitól kezdődően ez a rámpa széttagolódott, melynek következtében a Tiszai-főegység legnagyobb ré -szén intrashelf medencék és nagyméretű karbonátplat formok jöttek létre (BLEAHU et al 1994, HAAS & PÉRÓ 2004. Feltehetően egy ilyen, nagyméretű platformon, zátonyhát -téri lagúnában ülepedtek le a Szegedi Dolomit Formáció képződményei.…”

A dorozsmai márvány (Tiszai-főegység) kőzettani újravizsgálata: deformáció és fluidum hatása a mikroszerkezet fejlődésére

“…Míg az Alföld kristályos aljzata felszíni kibúvások hiá -nyában csupán mélyfúrások, karotázs szelvények és szeizmikus szelvények révén tanulmányozható, a Tiszai-fő egy ség keleti részét képező (HAAS & PÉRÓ 2004 Északi-Erdélyi-középhegységben számos felszíni feltárás található. Itt több márvány előfordulást is ismerünk, amelyek közül a legjelentősebbek a Kisbihari/Biharia-taka ró rendszerben találhatóak.…”

From nappe stacking to exhumation: Cretaceous tectonics in the Apuseni Mountains (Romania)

“…An important aspect of the Apuseni Mountains is the exposed contact between the Tisza and Dacia Mega-Units (see Fig. 1; Sǎndulescu 1994; Haas and Péró 2004; Csontos and Vörös 2004; Schmid et al. 2008; Kounov and Schmid 2013).…”

“…Both mega-units experienced a significant change in fossil assemblage during the Bathonian, which indicates that they had come under the influence of the Adriatic palaeobiogeographic realm (e.g. Vörös 1977, 1993; Lupu 1984; Haas and Péró 2004). Palaeomagnetic data show a common apparent polar wander (APW) path for the European plate and the Tisza Mega-Unit up into the Cretaceous, 130 Ma ago (Hauterivian/Barremian; Martón 2000).…”

“…The Tisza Mega-Unit is a large composite structural unit comprising three main nappe systems of Alpine origin: Mecsek (including the Szolnok Unit), Villány-Bihor (Bihor), and Békés-Codru, referred to as Codru (Fülöp 1994; Lelkes-Felvári et al. 2003; Haas and Péró 2004). In the Apuseni Mountains, the Tisza Mega-Unit only comprises the Bihor Unit and the Codru Nappe System according to Schmid et al.…”