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Abstract: Geodynamic Evolution of the Eastern Margin of the Precaspian Basin from Devonian to Permian

Gerard Fries, Jean-Loup Liger

The Precaspian basin can be considered as a post orogenic collapse basin initiated during the Lower Permian and continuously subsiding to the present time. Based on field studies, well data, reprocessed seismic and seismic acquired by Elf Aquitaine on the Temir licence and surrounding areas, a detailed geodynamic framework can be defined in the eastern part of the Precaspian basin.

From Devonian to Upper Carboniferous time, this area still corresponds to the western margin of the Uralian Ocean. This margin is characterized by two depositional domains:

- a western landward domain marked by limited sedimentation, possibly often emerged ;

- a eastern, seaward, more subsident domain with deposition of several thousands meters of clastics and carbonates ;

Closing of the Uralian Ocean had already begun during early Devonian but the western margin is still characterized by distensive tectonic features.

During the Lower Permian the final closure of the Uralian Ocean created inverted structures in the foreland; the western domain began to subside, initiating the eastern part of the Precaspian basin.

During the Kungurian (terminal Lower Permian), an evaporitic sequence was deposited followed by a thick clastic sequence of Upper Permian age; the eastern part of the Precaspian basin had obtained its current form at the start of this period.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France