Collaborative Research: Evaluating the evolution of the southern Himalayan-Tibetan orogeny: What happened during Paleocene-Eocene time?

大约5900万年前，印度和亚洲之间持续的构造碰撞形成了地球上最高的山脉。虽然喜马拉雅山脉过去2800万年的构造史有很好的记录，但对碰撞的早期阶段仍然知之甚少。在碰撞的早期阶段，尼泊尔北部和西藏南部地区的沉积岩被强烈地褶皱和弯曲。该项目将使用新的现场和实验室分析技术来确定该地区的岩石在碰撞早期阶段是如何变形的。这项工作的结果将有助于区分印度-亚洲碰撞的模型，并评估西藏南部地区是否包含~ 2000公里的缩短。此外，本项目将：1。加强对历史上代表性不足群体的研究生和本科生的多学科培训；2. 加强国际科学合作；和3。为来自历史上代表性不足的群体的K-12学生开发新的和扩大现有的以科学为重点的拓展机会。本项目主要研究喜马拉雅—青藏造山带南缘的特提斯褶皱冲断带，以确定其缩短的样式、幅度和时间。从大约5900万年前的碰撞到大约2800万年前最古老的喜马拉雅冲断带的演化，人们对褶皱冲断带的演化知之甚少。从北部的印度河-雅鲁藏布河缝合带到南部的藏南拆离体系的完整研究将建立一个包含所有变形尺度的最小缩短估计，并确定古新世-始新世时期（6000万至3000万年前）发生了什么。研究将集中于四个样带，将结构现场研究与实验室分析相结合，包括磷灰石裂变径迹、锆石中的(U-Th)/He和锆石碎屑的U-Pb年代学。这些数据将告知新的平衡截面和四个热动力学模型。结果将用于特提斯褶皱冲断带演化的新模型，该模型将与尼泊尔和不丹的现有剖面相结合，以提供整个系统的岩石圈演化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The ongoing tectonic collision between India and Asia began about 59 million years ago, creating the highest mountains on Earth. While the tectonic history of the last 28 million years is well documented in the Himalayan Mountains, the earlier phase of the collision remains poorly understood. During this earlier phase of collision sedimentary rocks were intensely folded and buckled in the region north of Nepal in southern Tibet. This project will use new field and laboratory analytical techniques to determine how the rocks in this region were deformed during the early phase of the collision. Results from this work will help discriminate between models for the India - Asia collision and evaluate whether the southern Tibet region contains ~2,000 km of shortening. In addition, this project will: 1. enhance multi-disciplinary training of graduate and undergraduate students from historically underrepresented groups; 2. strengthen international scientific collaborations; and 3. develop new, and augment existing, science-focused outreach opportunities for K-12 students from historically underrepresented groups.This project focuses on the Tethyan fold-thrust belt on the southern margin of the Himalayan-Tibetan orogen in order to determine the style, magnitude, and timing of shortening. Little is known about the evolution of the fold-thrust belt from collision at ~59 million years ago until the oldest dated Himalayan thrust at ~28 million years ago. A complete study from the Indus-Yarlung suture zone in the north to the South Tibetan detachment system in the south will establish a minimum shortening estimate that incorporates all scales of deformation, and determine what happened during Paleocene-Eocene time (60 to 30 million years ago). Research will focus on four transects that combine structural field studies with laboratory analyses of apatite fission track, (U-Th)/He in zircon, and U-Pb detrital zircon geochronology. These data will inform new balanced cross sections and four thermokinematic models. Results will be used in new models for the evolution of the Tethyan fold-thrust belt, which will be combined with existing cross sections in Nepal and Bhutan to provide a lithospheric evolution of the entire system.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.