How Does the Lower Crust Thicken and Grow During Continent Collisions? A Case Study of the Pamir

大陆碰撞期间下地壳如何增厚和生长？

• 批准号: 0838269
• 负责人: Bradley Hacker
• 金额: --
• 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: 2009-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0838269&HistoricalAwards=false
• 关键词: How; Does; Lower; Crust; Thicken

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Continent collisions can form large plateaus, like Tibet, producing thick crust and high topography that affects climate change. How plateaus grow to become so large is unresolved: either the lower parts of Earths crust flow at depths where the temperatures are high (30 km), or the crust thickens in a more brittle fashion along faults that transect the entire crust. This research focuses on this question using exposures of the lower crust in the Pamir Mountains of Tajikistan. The impact of this research should be considerable and broad because of the archetypal nature of the Tibetan and Pamir plateaus.The PIs test models for crustal thickening within the framework of three hypotheses: the Pamir lower crust was thickened and exhumed by local intracontinental shortening during the Cenozoic, thickened by Cenozoic long-distance flow and exhumed by local intracontinental shortening during the Cenozoic, or thickened and exhumed mostly before the collision between India and Asia. These hypotheses will be evaluated by U/Pb dating of zircon to determine crystallization ages of plutons, Lu-Hf and Sm-Nd dating to measure crustal thickening ages, thermobarometry to determine exhumation depths, 40Ar/39Ar, fission-track, and (U+Th)/He dating to constrain thermal histories, and structural analysis to determine deformation histories.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。大陆碰撞可以形成像西藏这样的大高原，产生厚地壳和影响气候变化的高地形。高原是如何变得如此之大的还没有得到解决：要么是地壳的下部在温度较高的深度（30公里）流动，要么是地壳沿着沿着横切整个地壳的断层以更脆的方式增厚。本研究利用塔吉克斯坦帕米尔山脉下地壳的暴露资料来探讨这一问题。由于青藏高原和帕米尔高原的原型性质，这项研究的影响应该是相当大和广泛的。PI在三个假设的框架内测试地壳增厚模型：帕米尔下地壳在新生代受局部陆内缩短作用增厚并折返，在新生代受长距离流作用增厚并受局部陆内缩短作用折返，或者在印度和亚洲碰撞之前被加厚和挖掘出来。这些假说将通过锆石U/Pb定年法确定岩体的结晶年龄，Lu-Hf和Sm-Nd定年法测量地壳增厚年龄，热压法确定折返深度，40 Ar/39 Ar、裂变径迹和（U+Th）/He定年法确定热历史，以及构造分析确定变形历史。