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

陆-陆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，青藏高原作为一个天然的实验室脱颖而出，在那里我们可以检验关于一个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显著不同的上地幔结构。因此，上地幔是区分可能的碰撞模型和解开高原原型形成的关键。这项研究的目的是确定青藏高原及邻区的高分辨率三维上地幔P和S速度结构。PIS将收集和处理研究区300多个宽带台站的上地幔距离地震的有效地震波形数据。这些研究应该会大大提高上地幔的横向和深度分辨率，比所有以前的研究都有可能。拟议的研究结果可以用来验证或排除现有的碰撞模型，并开发新的模型。本研究课题还与上海外国语大学目前正在开发和教学的几门本科生和研究生课程(板块构造学和地球动力学)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.