OBLIQUE RIFT GEOMETRY OF THE WEST SIBERIAN BASIN: TECTONIC SETTING FOR THE SIBERIAN FLOOD BASALTS

Abstract

We use magnetic intensity data to determine the geometries of basalt-filled rifts of the West Siberian Basin. En echelon graben arrays suggest a component of right-lateral, north-south shear during east-west extension (present co-ordinates). Several major exposed faults at the basin margins, mainly within the Altaid orogenic belt, underwent right-lateral strike-slip in the Late Permian-Early Triassic interval. The combined datasets show that the Siberian flood basalts were erupted during right-lateral oblique extension between the Urals and the Siberian craton, centred on a triple junction in the NE of the West Siberian Basin.