Crustal thickness variations, flexural isostasy and the gravity field in Tibet-Quinghai Plateau

Our study investigates the crustal structure of the Tibet-Quinghai plateau in terms of the flexural isostatic model. Constrained gravity inversion is used to formulate a model of crustal thickness variations, adopting the results from different geophysical studies. The great sedimentary basins, the Tarim and Qaidam basins, are modelled. The compatibility of the resulting crustal model with the flexural isostatic model is studied, allowing 2D variations of elastic thickness (flexural rigidity). The crustal model is found to be compatible with the flexural isostatic model, the elastic thickness values being generally low over most of the plateau and having systematically higher values over the Tarim and Qaidam basins. The high elastic thickness values correlate with low heat flow and low level of seismicity, supporting the hypothesis that the Tarim and Qaidam basins act as rigid blocks, surrounded by deformable crustal material.