青藏高原东北缘地壳和上地幔顶部三维结构与形变机制的地震学研究

青藏高原东北缘位于青藏高原向大陆内部扩张的前缘位置，是研究欧亚板块与印度板块碰撞造成青藏高原地表抬升、壳幔形变和演化动力学机制的窗口。但目前对于青藏高原东北部地区大规模的地表运动以及由碰撞引起的地壳、岩石圈形变仍未有定论，这也是地震学和地球动力学研究领域的热点问题。本项目将充分利用中国地震局在青藏高原东北缘区域的台网及其它可观测到的地震波形资料，采用接收函数和背景噪声伴随层析成像等地震学技术，获取青藏高原东北部及其周边区域的地壳和上地幔各向异性、地壳厚度、壳内Vp/Vs、地壳和上地幔顶部三维瑞雷面波精细速度结构等资料。结合已有的地质学、地球物理学以及地球动力学等研究成果，构建青藏高原东北缘区域地壳和上地幔顶部的三维结构图。进而深入探讨青藏高原东北缘的壳幔耦合情况、地壳变形、地表抬升的主要动力学机制。本项目研究对进一步认识青藏高原形成机制和变形演化的动力学过程具有重要的科学意义。

The large-scale surface deformation, uplifting and faulting occurring at the Tibetan plateau are generally believed to be caused by the continuous collisional compression and deep geodynamical process after the collision between the India and Eurasia. The Northeastern Tibet(NE tibet) is the front edge of continental expansion, which is the window to study the surface uplift geodynamical model, the crustal and mantle deformation and the evolution. However, the style and amount of the subsurface deformation induced by the collision, especially those inside the lower crust and upper mantle, are still debated, and are one of the fundamental problems in solid earth science. In this proposal, we plan to take advantage of the high quality waveform data recorded by the regional seismic networks of the China Earthquake Administration. We will apply our recently developed receiver function analysis technique，ambient noise adjoint tomography and other available seismic imaging techniques to develop a seismic image beneath NE Tibet from the crust to the upper mantle. The seismic image of the crust and mantle will include a three-dimensional Rayleigh wave velocity model, a map of crustal and upper mantle anisotropy, the Moho depth and Vp/Vs ratio. Combined with the results from geology, geophysics and geodynamics, we will build a 3D structure of the NE Tibet to study the state of the crust-mantle coupling, the deformation of crust and the mechanism of the crustal deformation and surface uplifting in NE Tibet. This project will provide important insights on the mechanism of the formation and deformation evolution of the Tibetan Plateau.