Extensional Fault Systems in the Ama Drime Range, Southern Tibet

藏南阿妈岭山脉的伸展断层系统

• 批准号: 0711140
• 负责人: Kip Hodges
• 金额: --
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711140&HistoricalAwards=false
• 关键词: Extensional; Fault; Systems; Ama; Drime

Recent research on the Himalayan-Tibetan orogenic system has focused on the role of monsoon climate in its development. In one controversial hypothesis, aggressive monsoon precipitation currently attracts the southward flow of a channel of middle crust from beneath the Tibetan Plateau to the Himalayan orogenic front. In this project, an Arizona State University research team, in collaboration with scientists from the Chinese Academy of Sciences, is testing the prediction that a recently active detachment occurs along the southern edge of the Tibetan Plateau at the approximate position of the Miocene South Tibetan fault system in the Ama Drime Range of southern Tibet. This transverse range has the overall form of a metamorphic core complex and is bound on the east and west by normal fault systems that strike directly into previously mapped strands of the South Tibetan fault system. The team is mapping critical intersections among these fault systems that are spectacularly exposed in this high-elevation region within the Himalayan rain shadow. They are also using the techniques of structural geology, tectonic geomorphology, low-temperature thermochronology, and cosmogenic nuclide dating to establish the late Cenozoic exhumation history of the Ama Drime massif and compare it with the exhumation history of the South Tibetan fault footwall east and west of the massif. These results will be used to evaluate the case for Quaternary channel extrusion and either falsify it or establish the structural and geomorphic consequences of deformation related to the upper bounding structure of the extruding channel.The concept of channel flow is a new and controversial idea in the field of tectonics. It suggests a strong coupling between climate and tectonics. The original version of the channel flow-extrusion hypothesis envisioned that Early-Middle Miocene southward extrusion of the channel was accommodated by slip on two north-dipping structures: the Main Central thrust and the South Tibetan fault systems. This study explores that idea that monsoon-induced channel flow continues today. The results of this work will be central to the ongoing debate over the style of deformation and the degree of erosion and tectonics coupling in the Himalaya.

喜马拉雅-青藏造山系统的研究主要集中在季风气候在其发展过程中的作用。在一个有争议的假设中，积极的季风降水目前吸引了从青藏高原下到喜马拉雅造山带前缘的中地壳通道向南流动。在这个项目中，亚利桑那州州立大学的一个研究小组与中国科学院的科学家合作，正在测试一个预测，即最近在青藏高原南部边缘沿着在藏南阿玛德林山脉中新世藏南断层系统的近似位置发生了一次活动拆离。这个横向范围具有变质核杂岩的整体形式，并在东部和西部由正断层系统限制，这些正断层系统直接进入先前绘制的藏南断层系统。该团队正在绘制这些断层系统之间的关键交叉点，这些断层系统在喜马拉雅雨影内的高海拔地区异常暴露。他们还利用构造地质学、构造地貌学、低温热年代学和宇宙成因核素测年等技术，建立了阿马德里梅隆隆的晚新生代折返历史，并将其与隆东西两侧藏南断层下盘的折返历史进行了对比。这些结果将被用来评估的情况下，第四纪通道挤压和伪造它或建立的结构和地貌的变形后果有关的上边界结构的挤压渠道。渠道流的概念是一个新的和有争议的想法在构造领域。这表明气候和构造之间有很强的耦合。最初版本的河道流动挤压假说设想，早-中中新世的河道向南挤压是由两个北倾构造的滑动所适应的：主中央冲断层和南藏南断裂系统。这项研究探讨了季风引起的河道水流今天仍在继续的想法。这项工作的结果将是中央的变形风格和侵蚀程度和构造耦合在喜马拉雅山正在进行的辩论。