Collaborative Research: Lhasa Block Top to Bottom--Lithospheric Evolution of Asia's Leading Edge

合作研究：拉萨地块自上而下——亚洲前沿的岩石圈演化

• 批准号: 1111586
• 负责人: Timothy Harrison
• 金额: $ 58.24万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1111586&HistoricalAwards=false
• 关键词: Collaborative; Research; Lhasa; Block; Top; Collaborative; Research; Lhasa; Block; Top

The Himalaya?Tibet orogenic system has been the subject of extensive research for decades, and continues to be a fruitful laboratory for understanding orogenic processes and continental evolution. Geological and geophysical studies have provided important insights into the structure and dynamics of the modern system, but imparted less information about the orogen?s early development, and the characteristics of the colliding continents that may affect subsequent evolution. The goal of this project is to investigate how crustal and lithospheric thickness changes in southern Tibet in order to establish the ?boundary conditions? for the India-Eurasia collision (~50 My ago) and how lithosphereic thickness changes during and after collision. As pointed out by the PIs, lithospheric thickness defines the thermal state and rheology of the crust and lithosphere, which are important boundary conditions and properties necessary for understanding the nature of crustal and lithospheric deformation during collision.The PIs will integrate geochemistry, geochronology, paleoelevation, seismology, tectonics, and modeling to understand the pre-collision structure and evolution of the leading edge of the southern Asian continental margin ? the Lhasa block ? and its role in controlling the development of the broader orogen. They seek to answer two sets of related questions:? How has the crustal thickness of the Lhasa block evolved from collision to the present?? How have the elevation and denudation histories changed through time?? What role does metamorphism play in altering crustal rheology and density and as a consequence facilitate surface uplift and erosion?? What is the contribution of lithospheric deformation to thickening of the region?This set of questions is relevant because of the way crustal thickness and surface elevation can influence the mechanics of an orogen.The second set of related questions addresses the later evolution of the Lhasa block:? What is the origin of post-collisional magmas?? To what extent has melting contributed to crustal weakening and flow?? How have magmatic and aqueous fluids and lateral heterogeneity in their distribution influenced evolution and deformation of the Lhasa block?? Why are elevations in the Lhasa block relatively uniform despite considerable variations in geology, exhumation, and deep structure?The importance of these questions derives from the control that rheology and its spatialvariations play in determining how orogens deform at large and small scales.

许多数十年来，喜马拉雅山脉造山机系统一直是广泛研究的主题，并且继续是理解造口过程和大陆进化的富有成果的实验室。地质和地球物理研究为现代系统的结构和动力学提供了重要的见解，但对造山基因的早期发育的信息较少，以及可能影响后续进化的碰撞大陆的特征。 该项目的目的是研究西藏南部的地壳和岩石圈厚度如何变化以建立“边界条件”？对于印度 - 欧亚碰撞（〜50我的AOGA）以及岩石圈在碰撞期间和之后的厚度如何变化。 如PI所指出的那样，岩石圈的厚度定义了地壳和岩石圈的热状态和流变学，这是理解碰撞过程中地壳和岩石圈变形的性质所必需的重要边界条件和特性。PIS将整合地球化学，古代学，古代学，Seolvation，Seolvation，Sequonology，Sequonology of Secton和Modelition of Secton和Modelition of Secton和Modelition of Sector and section and section and section and section and section and Section and Section and of Section和模型，并将其整合起来。大陆边缘？拉萨街区？及其在控制较宽造山基因的发展中的作用。 他们试图回答两组相关问题：拉萨块的地壳厚度如何从碰撞演变为现在？高程和剥夺历史的变化如何随着时间的流逝而变化？变质作用在改变地壳流变学和密度方面起着什么作用，因此有助于表面隆起和侵蚀？岩石圈变形对区域增厚的贡献是什么？这组问题是相关的，因为地壳的厚度和表面升高的方式会影响造山机的力学。第二组相关问题解决了LHASA块的后期演变：？后粉碎后岩浆的起源是什么？熔化在多大程度上导致地壳削弱和流动？岩浆和水性流体和分布的侧向异质性如何影响拉萨块的进化和变形？为什么尽管地质，挖掘和深层结构发生了很大差异，但LHASA块中的高程相对均匀？这些问题的重要性来自流变学及其空间自变在确定Orogens在大型和小尺度上如何变形的控制。