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The morphology of west Siberia suggests the presence of huge wrench faults, which also can be seen on Landsat imagery. Many of these faults have been confirmed by geophysical surveys and subsurface data. However, Soviet geologists have not always recognized the importance of
strike-slip components with horizontal displacements of dozens, or even hundreds of kilometers. Pre-Mesozoic faults, in part reactivated during the Mesozoic, had an important role in controlling the distribution of Jurassic-Cretaceous organic-rich shales and porous clastics. Wrench faults that developed during the Late Cretaceous-Tertiary mark the limit of the major petroleum provinces of west Siberia: the oil-rich Mid-Ob province, the less-prolific southern basin, the northern province (the world's leading gas region), the as yet little-drilled Khatanga trough, plus several other less-explored areas. Furthermore, most of the low-closure hydrocarbon-bearing structures seem to be of the drag type, being directly related to wrenching.
The relationship between strike-slip faults and the comparatively much smaller petroleum accumulations within the Paleozoic of the basin's southern part is more difficult to understand.
Future exploratory drilling to Mesozoic targets, including the deep-seated Jurassic in northern regions, and the Cretaceous in little-explored, low-accessibility parts of central-southern regions, should result in considerable new reserves of oil being found, probably exceeding the amount already found. A comprehensive wrench-tectonical approach may help find these undiscovered resources.
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