On Karig convective rolls within the mantle wedge beneath the Timan-Pechora plate as the mechanism of transport of the hydrocarbons at Paleozoic

Previously not carried out investigation is performed for finite-amplitude 2D small-scale mantle convection in the mantle wedge above the slab subducting at extremely small angle, which appears to be the case at Paleozoic in the course of closing of the former Urals ocean and subduction of the Russian plate under the Timan-Pechora one. Topography depressions and uplifts at the Timan-Pechora lithospheric plate alternate quasi periodically and are nearly parallel to the South-Western border of the plate. This probably is indicative of the convective origin of topography spatial undulations, the convection at the mantle wedge being due to shear heating in the mantle slab-induced flow. Numerical modeling of the thermal mantle convection accounting for the effects of phase transitions at 410 km and 660 km depths and temperature- and pressure dependence of viscosity for «wet» olivine shows the subduction velocity ~ 6 cm·y-1 to correspond to convective cell (Karig rolls) dimension of the same scale as the wavelength of the relief variations, horizontal extent of convection region being equal to horizontal extent of Timan-Pechora oil- and gas bearing province.