Application of Numerical Methods for New Estimate of Rheology Constants in the 2d Computer Model of the Mantle Wedge Thermal Convection as a Possible Physical Mechanism of Hydrocarbons Transport
For both Newtonian and non-Newtonian mantle rheology laws, the numerical model of the 2D dissipationdriven mantle wedge thermal convection is constructed for the case of subduction of the Black sea micro-plate under the Crimea peninsula with the account taken of the phase transitions in the mantle. The horizontal extent of the positive 2D heat flux anomaly zone localized in the rear of the Crimea mountains is shown to correspond to the model subduction velocity ≥10 mm per year for the water content of one weight %. For Newtonian rheology upwelling convective flow transporting heat to the Earth’s surface is formed at the subduction velocity of ~102 mm per year, which appears too excessive and probably evidence of that the non-Newtonian rheology dominates in the mantle wedge. In the case of non- Newtonian rheology, the velocity in convective vortices in the mantle wedge exceeds 10 m per year. The subduction velocity may be less than 10 mm a year for the water content in the mantle wedge over ~1 weight %. The upwelling convective flow is shown to transport mantle hydrocarbons to the Earth’s surface since the zone of oil and gas accumulation coincides with the 2D one of heat flux anomaly.
