Upper mantle flow beneath the Northwest of China and its lithospheric dynamics
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The regional isostatic gravity anomalies in the Northwest of China (80°–95°E, 35°–45°N) and corresponding problems of mantle dynamics are discussed in detail in this paper. It is assumed that the anomaly of isostatic gravity in this region is caused by the nonuniformity in density and that the boundary deformation is related to the thermal convection in the upper mantle. Using the correlation equation between the mantle flow and regional anomalies of isostatic gravity as a constraint, we have calculated the patterns of upper mantle convection. The result shows that the regional lithospheric tectonics is strongly correlated with the upper mantle flow. The uplift of the Tianshan and Kunlun Mountains corresponds to the upward flows in the mantle while the depression of the Tarim, Turpan and Junggar Basins corresponds to the downward flow. Meanwhile, we have also worked out a basic framework for the lithospheric dynamics of the Northwest of China. It is reasonable to infer that the mantle flow and the horizontal compression from the India plate may act as the main driving forces for the lithospheric tectonics of this region.
Key wordsupper mantle lithospheric dynamics thermal convection
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