Europrobe seismic reflection profiling across the eastern Middle Urals andWest Siberian Basin

New deep seismic reflection data provide images of the crust and uppermost mantle underlying the eastern Middle Urals and adjacent West Siberian Basin . Distinct truncations of reflections delineate the late-orogenic strike-sl ip Sisert Fault extending vertically to similar to 28 km depth, and two gen tly E-dipping reflection zones, traceable to 15-18 km depth, probably repre sent normal faults associated with the opening of the West Siberian Basin. A possible remnant Palaeozoic subduction zone in the lower crust under the West Siberian Basin is visible as a gently SW-clipping zone of pronounced r eflectivity truncated by the Moho. Continuity of shallow to intermediate-de pth reflections suggest that Palaeozoic accreted island-arc terranes and ov erlying molasse sequences exposed in the hinterland of the Urals form the b asement for Triassic and younger deposits in the West Siberian Basin. A hig hly reflective lower crust overlies a transparent mantle at about 43 km dep th along the entire 100 km long seismic reflection section, suggesting that the lower crust and Moho below the eastern Middle Urals and West Siberian Basin have the same origin.