--> Abstract: Geology and Discussion of the Petroleum System of the Styrian Basin, by R. A. Neumayer and M. Blach; #90942 (1997).

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Abstract: Geology and Discussion of the Petroleum System of the Styrian Basin


NEUMAYER RICHARD A. (RAG), M. BLACH

The Styrian Basin is a Miocene pullapart basin between the Eastern Alps and the Pannonian plate. It is the northwestern most subelement of the Pannonian Basin. The basement consists of anchimetamorphic Paleozoic carbonates and phyllites and/or Austroalpine crystalline. During the moderate subsidence phase in the Ottnangian, widespread coal-rich sediments were deposited in floodplain and lacustrine swamp environments. The accelerated subsidence rate during the Karpatian led to a marine ingression and island arc volcanism (andesitic) arose synchronously. This caused an elevated thermal gradient between 19 and 16 my in large proportions of the Styrian Basin. During a regression phase at the end of the Karpatian, clastic fans prograded towards the basin center. The end of the Karpatian is defined as period of strong tectonic unrest (erosion, Styrian Phase). On top of this unconformity huge amounts of coarse clastic sediments (Badenian Basal Conglomerates) were deposited. At times of constant sea level, carbonate platforms (Lithothamnium limestone) evolved. In the central basin a deep marine environment with turbidites existed. At the end of the Lower Badenian the sea reached its largest extent. The separation between Pannonian Basin and the Mediterranean Sea happened during the Sarmatian (change of saline towards brackish). The Upper Miocene and Pliocene sediments are limnic to fluvial. Several wells have been drilled in the basin for different target formations. In contrast to the Pannonian Basin, which is a prolific HC province, no economic discoveries have been made so far. Gas shows have had high CO2 contents or were minimal although modeling hasshown promising indications.

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