The Deformation History of the India-Asia Suture Zone, Lopukangri Rift, South-Central Tibet

定量构造模型解释了西藏-喜马拉雅造山带深部地壳岩石的演化，需要将它们与印度和亚洲之间的缝合带联系起来的过程。所有描述缝合带动力学的模型都是对缝合带岩石的运动学历史、起源和压力-温度-时间演化的预测。这个项目是由休斯顿大学的一个研究小组与中国科学院的科学家合作开展的，他们利用了印度和亚洲之间的缝合带——印度河-鸭鲁河缝合带的一个罕见的深层和浅层暴露，该缝合带位于西藏中南部，由洛普康日裂谷提供，这个裂谷从拉萨地体延伸到印度次大陆约150公里。对裂谷的侦察研究表明，裂谷隆起的下盘为研究深部缝合带岩石的变形史提供了一个窗口，而裂谷的上盘则记录了缝合带浅部岩石的变形史。目的是确定：1)印度-亚洲缝合带内的地壳结构和形变运动学；2)缝合带岩石（俯冲的印度板块或亚洲板块）的偏移；3)确定缝合线变质作用的性质和时间；4)变质缝合带岩石的掘出率；5)深部缝合带岩石记录的地质史与浅部地壳区和喜马拉雅冲断带的地质史的关系。研究人员将使用多种技术研究缝合带岩石的变形历史、岩石成因和热历史，包括野外测绘和构造分析、热气压测量、Nd同位素地球化学、40Ar/39Ar热年代学和Sm-Nd石榴石年代学。所得数据将直接解决藏喜马拉雅造山和缝合带动力学模型的预测问题。西藏-喜马拉雅造山带是活跃大陆碰撞的典范；因此，对其演化的研究在形成对造山过程和大陆增生的概念性理解方面发挥了重要作用。虽然从西藏-喜马拉雅山脉的地质和地球物理研究中出现了许多造山的地球动力学模型，但它们对中地壳和下地壳行为的预测在很大程度上仍未经检验，因为一般来说，进入深部岩石的途径仅限于高喜马拉雅的锋面区域。该项目利用了山脉内部这些深层岩石的不同寻常的暴露，并采用同位素地球化学、地质年代学和地质测绘技术来解决假定在洲际碰撞期间发生的过程，例如，缝合带的深层结构，以及缝合带岩石从深处转移到地表的速度。将这些新的观测结果与喜马拉雅和西藏其他地区现有的地质和地球物理数据进行整合和分析，将对山地带和大陆演化的概念理解产生重大影响。该项目涉及与中国科学家的重要合作，支持早期职业研究人员，并积极促进未被充分代表的群体参与地球科学研究。

Quantitative tectonic models that explain the evolution of deep-crustal rocks in the Tibet-Himalayan orogen call upon processes which link them to the suture zone between India and Asia. Inherent in all models that describe the dynamics of the suture zone are predictions of the kinematic history, origin, and pressure-temperature-time evolution of suture zone rocks. This project, carried out by a research team from the University of Houston in collaboration with scientists from the Chinese Academy of Sciences, exploits a rare exposure of the deep and shallow portions of the suture between India and Asia, the Indus-Yalu suture zone, in south-central Tibet afforded by the Lopukangri rift, a rift that extends approximately 150 km from the Lhasa terrane into the Indian subcontinent. Reconnaissance studies of the rift show that its uplifted footwall provides a window into the deformation history of deep suture zone rocks, while the history of the shallow portion of the suture zone is archived in its hanging wall. The goals are to determine: 1) the crustal architecture and kinematics of deformation within the India-Asia suture zone; 2) the derviation of the suture zone rocks (subducted Indian plate or Asia); 3) determine the nature and timing of metamorphism in the suture; 4) the exhumation rate of the metamorphic suture zone rocks; 5) the relationship between the geologic history recorded in deep suture zone rocks to that of the shallow crustal regions and the Himalayan thrust belt. The deformation history, petrogenesis, and thermal history of suture zone rocks will be examined using a variety of techniques including field mapping and structural analysis, thermobarometry, Nd isotope geochemistry, 40Ar/39Ar thermochronology, and Sm-Nd garnet geochronology. The resulting data will directly address the predictions of models for Tibet-Himalayan orogenesis and suture zone dynamics.The Tibet-Himalayan orogen is a paradigm for active continental collision; hence studies of its evolution have played a major role in shaping the conceptual understanding of mountain-building processes and continental growth by accretion. While numerous geodynamic models of mountain building have emerged from geologic and geophysical studies of the Tibet-Himalayan Range, their predictions for the behavior of middle and lower crust remain largely untested because access to deep rocks is, in general, limited to the frontal regions in the High Himalaya. This project exploits an unusual exposure of these deep rocks in the interior of the range and employs techniques in isotope geochemistry, geochronology, and geological mapping of the to address processes hypothesized to operate during intercontinental collision, such as, the deep structure of suture zones, and the rates at which suture zone rocks are translated from great depths to the surface. Integration and analysis of these new observations with existing geologic and geophysical data from other parts of the Himalaya and Tibet will significantly impact the conceptual understanding of the evolution of mountains belts and continents. The project involves a significant collaboration with Chinese scientists, supports early career researchers, and actively promotes participation of underrepresented groups in earth science research.