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为了研究青藏高原东北部块体构造变形的深部驱动机制 ,笔者对青藏高原东北部的天然地震观测数据进行地震层析反演 ,并结合同一剖面的接收函数及各向异性结果进行讨论。介绍了ACH方法的基本原理 ,论述了由于印度板块向北俯冲的强大的持续作用力 ,造就了NE向俯冲到柴达木盆地之下的昆仑造山带 ,并发现在巴颜喀拉地体下方壳幔内的仰冲活动。壳幔内的低速体十分显著地出现在阿尼玛卿缝合线以北 ,深度可达 30 0km。推断该低速体可能与昆仑断裂在深层的剪切作用有关。深部资料显示该区莫霍界面由北向南逐渐加深 ,这与青藏高原东北部的岩石圈减薄现象一致 ,而且与印度板块向北运动的远程效应有关。另外 ,地震层析结果及各向异性分析也支持青藏高原东北部主应力方向转为NE向的观点。
In order to study the deep driving mechanism of block deformation in the northeastern Qinghai-Xizang Plateau, the author performs seismic tomographic inversion of the natural seismic data in the northeastern Qinghai-Xizang Plateau, and discusses the receiver functions and anisotropy results in the same section. The basic principle of the ACH method is introduced. The strong sustained action of subduction of the Indian plate to the north and the Kunlun orogenic belts subducted to the Qaidam basin are created. It is found that under the shell of the Bayan Har Yang Chong Yang activities within the mantle. The low-velocity body in the crust is very significant in the north of Animaqing suture, reaching a depth of 300 km. It is concluded that this low velocity body may be related to the shearing effect of the Kunlun fault in the deep layer. Deep data show that the Moho interface in this area is gradually deepening from north to south, which is consistent with the lithospheric thinning in the northeastern Tibetan Plateau and related to the long-range effect of Indian movement to the north. In addition, the results of seismic tomography and anisotropy also support the viewpoint that the principal stress direction in northeastern Qinghai-Tibet Plateau should turn to NE direction.