Geodynamic control on the petroleum habitat of the Uralian Foreland

Abstract

A comparative study of the Uralian Foreland in the Timan-Pechora and Volga Urals basins reveals considerable differences in structure and petroleum habitat. These differences were in large measure controlled by their geodynamic settings. A typical scenario of the continental marginal basin which subsequently was modified in the foredeep basin took place in the Timan-Pechora basin. The sedimentary fill of the basin is made up of the Phanerozoic deposits only. The principal oil source rock is provided by the prolific Domanik Suite broadly developed in is eastern part of the basin. The mature Domanik source rocks charged the majority of oil and gas fields of the Timan-Pechora Basin. In the Volga Urals basin the sedimentary fill includes two overlapping foredeep sequence – Riphean and Paleozoic, of which the Riphean one is much thicker. The Riphean depocenters were subjected to structural inversion during the docking of the Magnitogorsk island arc to the Uralian margin in the Middle Devonian-Frasnian. The inversion was accompanied by the thickening of the Riphean section due to the reactivation of the pre-existing Precambrian deformation and caused the regional uplift in the Southern Uralian Foreland. This uplift led to shifting of the Domanik troughs to the westerly outboard part of the Volga-Uralian Basin. The Domanik source rock remained immature over much of the Southern Uralian Foreland which is interpreted to be a result of the inversion of the Riphean depocenters and related regional uplift. It is proposed that the enormous clustering of large oil deposits in the Paleozoic section of the south-eastern part of the Volga Uralian Basin was to a much extent produced by the charging from the multi-kilometer thick Riphean section of the Southern Uralian Foreland.