High Resolution Upper Mantle Structure beneath the Tibetan Plateau and Its Surroundings from Studies of Seismic Waveforms

大陆-大陆碰撞造山是地球上最重要的造山过程，其机制尚不清楚。印度和亚洲之间的碰撞是这种碰撞的最大区域，并产生了世界上最壮观的地形。在这个地区，青藏高原作为一个自然实验室脱颖而出，我们可以在这里测试关于影响大陆动力学的基本过程的假设。在各种研究中获得的碰撞模型，预测了高原下明显不同的上地幔结构。因此，上地幔是区分可能的碰撞模型和揭示这种高原原型如何形成的关键。本研究的目的是确定青藏高原及其邻近地区的高分辨率三维上地幔P和S速度结构。pi将收集和处理研究区域300多个宽带站的上地幔距离范围内地震的可用地震波数据。这些研究将提供比以往所有研究都更好的上地幔横向和深度分辨率。所提出的研究结果可用于验证或驳回现有的碰撞模型，并开发新的碰撞模型。该研究课题也与PI目前在SLU开发和教授的几门本科和研究生课程（板块构造与地球动力学）密切相关。这项拟议的研究涉及圣路易斯大学和中国地震局地球物理研究所的合作。它将使用几个跨国项目（中国、法国、德国、美国等）在西藏收集的地震数据。

Mountain building by continent-continent collision is the mostimportant orogenic process on Earth whose mechanism is notwell understood. The collision between India and Asia is thelargest region of such collision and has produced the world's mostspectacular topography. Within this region, the Tibetan Plateaustands out as a natural laboratory in which we can test hypothesesregarding a fundamental process that has impacted continentaldynamics. Collision models, obtained in various studies, predictsignificantly different upper-mantle structure beneath the plateau.The upper mantle, therefore, holds a key to differentiating betweenpossible collisional models and to unraveling how this archetypeof plateaus came into being. The objective of this research isto determine high resolution 3-D upper-mantle P and S velocitystructure beneath the Tibetan Plateau and neighboring regions.The PIs will collect and process available seismic waveformdata of more than 300 broadband stations in the study area fromearthquakes in the upper-mantle distance range. These studiesshould provide much improved lateral and depth resolution in theupper mantle than it has been possible in all previous studies.The results of the proposed study can be used to verify or dismissexisting collision models and to develop new ones. The researchtopic is also closely related to several undergraduate and graduatecourses (plate tectonics and geodynamics) that the PI is currentlydeveloping and teaching at SLU. The proposed research involvescollaboration between Saint Louis University and the Institute ofGeophysics, Chinese Earthquake Administration. It will use seismicdata collected by several multi-national (China, France, Germany,USA, etc) projects in Tibet.