Csaba Péró

THE OLDEST TRIASSIC PLATFORM MARGIN REEF FROM THE ALPINE - CARPATHIAN REGION (AGGTELEK, NE HUNGARY): PLATFORM EVOLUTION, REEFAL BIOTA AND BIOSTRATIGRAPHIC FRAMEWORK

The 1:10,000 scale mapping of the southern part of the Aggtelek Plateau (Western Carpathians, Silica Nappe, NE Hungary) and the study of five sections revealed two Middle Triassic reef bodies. In the late Pelsonian the uniform Steinalm Platform was drowned and dissected due to the Reifling Event. A connection with the open sea was established, indicated by the appearance of gladigondolellid conodonts from the early Illyrian. Basins and highs were formed. In the NW part of the studied area lower - middle? Illyrian basinal carbonates were followed by a platform margin reef (early?-middle Illyrian; reef stage 1) developed on a morphological high. This is the oldest known Triassic platform margin reef within the Alpine-Carpathian region. The reef association is dominated by sphinctozoans and microproblematics. The fossils are characteristic of the Wetterstein-type reef communities. Differently from this in the SE part of the studied region a basin existed from the late Pelsonian until the early Ladinian. During the late Illyrian- early Ladinian, the reef prograded to the SE, and reef stage 2 was established. Meanwhile, on the NW part of the platform a lagoon was formed behind the reef. Based on our palaeontological study the stratigraphic range of Colospongia catenulata, Follicatena cautica, Solenolmia manon manon, Vesicocaulis oenipontanus must be extended down to the middle Illyrian. Synsedimentary tectonics were detected in the 1. Binodosus Subzone, 2. Trinodosus Zone - the most part of the Reitzi Zone, 3. Avisianum Subzone.

Structure of the Békés Basin Inferred from Seismic Reflection, Well and Gravity Data

The Bekes basin (areal extent 3900 km2) is a northwest-trending, Neogene basin located in southeast Hungary. The basin contains over 6500 m of synrift and postrift sedimentary fill. Middle Miocene synrift deposits are relatively thin and no Paleogene rocks have been reported to be present. The prerift section (basement) is composed of Mesozoic carbonate and clastic rocks and Paleozoic and older volcanic, igneous and metamorphic rocks. The Mesozoic rocks represent dominantly shallow-water environments and are up to 5000 m thick in the Bekes-Doboz Mesozoic trough and 2000 m thick in the Battonya-Pusztafoldvar Mesozoic trough.