--> Abstract: Compressional Tectonics and Hydrocarbon Aspects of the Ternberg-Ost Area (Upper Austria), by B. Gunzenhauser, B. Meier, and W. Zimmer; #90942 (1997).

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Abstract: Compressional Tectonics and Hydrocarbon Aspects of the Ternberg-Ost Area (Upper Austria)

GUNZENHAUSER, B., B. MEIER, and W. ZIMMER, OMV

The Cenozoic structural deformation along the southwestern Bohemian border zone and the hydrocarbon habitat are illustrated by seismic and borehole data from the Ternberg-Ost area.

Ternberg-Ost forms part of the Upper Austrian Molasse Zone with an autochthonous substratum composed mainly of Late Cretaceous deposits that unconformably overlie crystalline basement of the Bohemian Massif. Resulting from regional truncation, the autochthonous, Late Cretaceous sediments generally terminate against the north-northwest oriented Steyr fault zone along the southwestern border of the Bohemian Massif. Cretaceous and crystalline basement is unconformably overlain by transgressive, late Eocene sediments. East- and northward tilted halfgrabens filled by Upper Cretaceous, basement derived clastics signal initial syndepositional movements along the Bohemian border zone. The main pre-late Eocene uplift of the Bohemian basement blocks is achieved by right-lateral, transpressive movements along the Steyr fault zone.

Evidence for post-Eocene transpressive deformation along the main fault zone is given by thrust reactivation of the frontal thrusts, and by north- and eastward directed backthrusting. Internally, the Late Cretaceous and its basement substratum form a stack of generally southward-directed thrust wedges.

The main hydrocarbon play is formed by very good, oil-prone source rocks in the Oligocene "Fischschiefer" and the Upper Cretaceous sandstone reservoirs, often in combination with late Eocene sandstones. Traps are provided by fault-bound closures sealed against marls and claystones of the Oligocene Molasse.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria