柴达木-陇西地块运动与变形机制

Tectonic deformation patterns show complex lateral variations on the northeastern Tibetan plateau. Those variations cannot be completely explained by the lateral variations of the mechanic properties of crust and faults, but possibly reflect intrinsic mechanisms of the development of faults and the growth of the plateau in Tibet. To explain the existence of the variations of deformation needs rational kinematic models for quantitative analyses on different tectonic patterns. Deformable block models show better consistencies in both determinations of the slip rates on major strike-slip faults and the deformation features within blocks in comparison to observations. However, for the assumption of uniform internal strain, the present deformable block model is not applicable to handle the complexities in the lateral variation of tectonic deformation. We propose an addition of the description of heterogenic internal strain in response to block motion as a whole into present kinematic model of blocks. Under joint constraints from GPS velocities, geologic slip rates, inter-seismic deformation detected through InSAR technique, and focal mechanisms, the block models with the new description are expected to be used in quantitative analyses of balance and transformation between different tectonic deformation patterns. Furthermore, the kinematic mechanisms behind the lateral variations of tectonic deformation will be studied as proxies for understanding northward growing of the Tibetan plateau.

青藏高原东北部构造变形方式存在复杂的横向变化，这些变化不能完全由地壳和断层力学性质的横向变化来解释，而可能反映了断层扩展、高原生长的内在机制。对这种变化的解释，需要合理的运动学模型对构造变形作定量分析。可变形地块模型能较好地解释主要走滑断层上的滑动速率和块体内部的变形特征，但由于假设内部应变均匀分布，目前可变形地块模型无法应对构造变形横向变化的复杂性。本项目拟在目前模型的基础上，增加对由地块内部非均匀应变的描述，以GPS速度、地质学滑动速率、InSAR震间变形和震源机制为联合约束，定量分析柴达木-陇西地块构造变形方式间的平衡与转化关系，研究其横向变化的运动学特征，为研究青藏高原向北扩展的动力学机制提供依据。