Collaborative Research: Orogen-parallel Mid-crustal Flow and Exhumation of Domes Along the Southern Margin of the Tibetan Plateau

合作研究：青藏高原南缘造山带平行中地壳流动与穹窿折返

• 批准号: 0911416
• 负责人: John Cottle
• 金额: $ 4.14万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-10-01 至 2012-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911416&HistoricalAwards=false
• 关键词: Collaborative; Research; Orogen; parallel; Mid

Some of Earths largest and most intriguing geologic and geographic features, including the Alpine/Himalayan mountain chain, are the result of continental collision. Because continental collision systems are responsible for profound geologic change throughout a large portion of Earth?s history, understanding their complex dynamics is of fundamental importance to Earth Science. Geologic studies based on the rocks and structures preserved in eroded cores of collisional systems provide critical insights into the fundamental processes of mountain building including metamorphism, melting, deformation, and exhumation. Results of this work will help refine our knowledge, not only of individual processes, but also the extent to which they interact to both construct and destruct large mountain chains. Data from this project will form the basis for the development of curricular materials that will be distributed to middle school teachers and a website devoted to highlighting active geoscience projects in the Himalayas. This project will also support mentoring and education of graduate and undergraduate students, and with the help of the NSF Office of International Science and Engineering will initiate a wide-ranging international collaboration on the science. The Himalaya provide an exceptional opportunity to investigate the evolution of mid-crustal rocks in an active collisional system. Along the collisional front, the major structures that bound these mid-crustal rocks, the Main Central thrust below and South Tibetan detachment above, are offset or reactivated by young metamorphic domes like the Leo Pargil, the focus of this study. Such domes provide an important opportunity to study the generation of partial melt, the potential feedback between partial melt and exhumation, the affects of shear zone nucleation, and the rheology of the crust during dome formation. The high-grade rocks of the Leo Pargil dome have been exhumed during extension and dome formation within an active convergent setting along orogen-parallel thrust faults and low angle detachment faults that were active until the middle Miocene. In collaboration with US and international academic organizations this project will employ a field-and lab-based interdisciplinary investigation to explore the evolution of these rocks using 1) geologic mapping and detailed microstructural analysis, 2) isotope geochronology (U/Pb, Ar/Ar, [U+Th]/He), and 3) determination of metamorphic P-T-t paths. Results from Leo Pargil will be contrasted with that from other domes along the Himalayan front to generate a high-resolution model for the timing and kinematics of orogen-parallel mid-crustal flow and exhumation along the southern margin of the Tibetan plateau since the middle Miocene.

大陆碰撞的结果是地球上最大，最吸引人的地质和地理特征，包括高山/喜马拉雅山脉。由于大陆碰撞系统在整个地球的大部分历史中都导致了深刻的地质变化，因此了解它们的复杂动态对地球科学至关重要。 基于保存在碰撞系统侵蚀的岩心的岩石和结构的地质研究为山区建筑的基本过程提供了关键的见解，包括变质，熔化，变形和发掘。 这项工作的结果将有助于完善我们的知识，不仅是个人过程，而且还有助于它们与大型山脉相互作用的程度。该项目的数据将构成开发课程材料的基础，该课程材料将分发给中学教师，并致力于强调喜马拉雅山脉的活跃地球科学项目。 该项目还将支持研究生和本科生的指导和教育，并在国际科学与工程办公室的帮助下，将启动广泛的国际科学合作。 喜马拉雅山提供了一个非凡的机会，可以调查活跃的碰撞系统中中心岩石的演变。 沿着碰撞的阵线，在上面和南藏族偏离的主要中央推力的主要结构中，上面的主要中心推力被幼年的变质圆顶（如Leo Pargil）所偏移或重新激活，这是这项研究的重点。 这样的圆顶提供了一个重要的机会，可以研究部分熔体的产生，部分熔体和挖掘之间的潜在反馈，剪切带成核的影响以及圆顶形成过程中地壳的流变学。 在延伸和圆顶形成期间，在沿着基因平行的推力断层和低角度脱离断层的活动中，在延伸和圆顶形成期间已经挖掘出了狮子座帕吉尔圆顶的高级岩石，直到中新世中部。 与我们和国际学术组织合作，该项目将采用基于实地实验室的跨学科调查，使用1）地质映射和详细的微观结构分析探索这些岩石的演变，2）同位素地球人数（u/pb，ar/ar/ar/ar/ar，[u+th]/he），[u+th]/he），以及3）确定中要素p-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-t-paths。 Leo Pargil的结果将与沿喜马拉雅沿前部的其他圆顶形成对比，以生成一个高分辨率模型，用于自来后中新世以来的基因平行中近距离流和沿藏族高原沿藏高原南部边缘的造型和运动学的模型。