| Popis: |
Results of the correlation analysis of heat flow anomalies with distributions of density contrast (µz-parameter) in rifting and plume structures on eastern margin of Asia which prove selective return correlation of these parameters in intervals of depths corresponding to the provision of the subcrustal viscous layer (the deep interval 25–45 км) and astenosphere (the deep interval 70–90 км) are considered. The South-Okhotsk rift has anomalous characteristic, where subcrustal layer locates at the depth of 10–25 km, and astenosphere – 45–55 km. In most regions (South Okhotsk, Sea of Japan, Cathaysia) main contribution to the heat flow brings a subcrustal viscous layer, but in the Indigiro-Kolimsky – asthenosphere contribution is prevailed over subcrustal one. The heat flow from an asthenosphere on Ceinozoic borders of lithospheric plates is screened by subduction’s slabs. In the Chenzhou–Linwu fault zone at the boundary of the Yangtze plate and Cathaysia block the wide stretch-shear zone in lithosphere is revealed. The late is displayed by the density contrast minima at the depth interval of 30–100 km and heat flow anomalies. in this zone, on geological data, manifestations of stretching, viscous shear and oblique subduction are detected. The main contribution to thermal anomalies in rift structures is made by a subcrustal viscous layer. Identical correlation of Q and µz-параметра in the areas removed from each other testifies to an identical deep structure and universality of tectonic states on eastern margins of the Asia where in space and time subduction’s rifting and plume processes are interfaced. Key words: heat flow, upper mantle, density contrast, rheology, Eastern Asia. |
