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Abstract: Relationships Between Variscan Strike-Slip Faults in the Paleozoic Basement and Oil-Gas Deposits in Its Mesozoic-Cenozoic Cover: West Siberian Sedimentary Basin as Example

Andrey F. Chitalin

The West-Siberian Sedimentary basin was filled during Mesozoic and Cenozoic. Polychronous compressive and extensional deformations and strike-slip faulting occurred at the time of sedimentary basin formation.

Late Variscan (Late Permian-Early Triassic) strike-slips in the basement took place as a result of N-S compression of the Central Asian Fold Belt. Strike-slips form wide and continuous shear zones which coincide with large oil and gas fields in the cover. Some strike-slips controlled distribution and formation of Permian and Triassic-Jurassic compressional and extensional local structures in the lower stage of the cover and anticlines in the upper stage of the cover. All these structures reveal potential oil and gas resources.

In the Triassic some of the N-S and SW-NE trending strike-slip faults in the axial part of the West Siberian Sedimentary basin were transformed into graben-rift structures of the Koltogorsk-Urengoy Rift Belt. These transtension structures occurred as a result of N-S compression and reactivation of the Late Variscan faults. The largest oil and gas fields have been formed in the cover above the Koltogorsk-Urengoy Rift Belt of the West Siberian Sedimentary basin.

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