Abstract:
Based on 297 focal mechanism solutions around the Ordos block, the stress field around the Ordos block was inversed. The inversion result indicates that the principal compression stress direction around the Ordos block is NE-SW and the principal tension stress direction is NW-SE. Hetao active fault subsidence zone, on north edge of the block, are under the joint action of the ENE-WSW horizontal compression and the NNW-SSE horizontal tension stress field. Weihe fault subsidence zone is under the tension of the nearly NS horizontal stress field. Shanxi faulted basin zone is under the tension of the NNW-SSE horizontal stress field. In the west of the Ordos block, the strikes of the principal compression stress axes from south to north, and turn gradually from ENE to NNE direction. Both the Weihe faulted basin zone and Hetao faulted basin zone are nearly EW-trending left-lateral shear zones with extension components, while both the Shanxi faulted basin zone and Yinchuan-Jilantai faulted basin zone are NNE-trending right-lateral shear zones with extension components, that accord with our study results. Our inversion results are similar with previous studies, which indicate the reliability of our study result.