Collaborative Research: Evaluating the role of terrane accretion on the evolution of indenter corner fault systems, an example from the eastern Himalaya

合作研究：评估地体增生对压头角断层系统演化的作用，以喜马拉雅东部为例

• 批准号: 2319476
• 负责人: Karl Lang
• 金额: $ 23万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2319476&HistoricalAwards=false
• 关键词: Collaborative; Research; Evaluating; role; terrane

The collision of continental tectonic plates produces some of the highest topography, deepest sedimentary basins, and highest potential for large earthquakes on Earth. To explain how these unique plate boundaries evolve, geologists commonly simulate a collision between a rigid tectonic plate that collides with and indents a weaker tectonic plate. Recent observations from the eastern Himalaya and Alaska instead suggest that indenting plates in nature are not entirely rigid, particularly when they contain pieces of crustal blocks accreted from prior collisions in the geologic past. This implies that active fault systems may also deform (and generate earthquakes) within the indenting plate as well as the indented plate, changing the way geoscientists understand plate boundary faults within continental collision zones. This project will study the complex tectonic setting of the eastern Himalaya, a natural laboratory for testing the hypothesis that prior accreted terranes fundamentally change the active fault systems at the margins of a collision zone. This research will address three Grand Challenges outlined in a 2018 NSF Community Vision Document for Tectonics research and will strengthen international ties between US scientists and researchers at multiple Indian universities and research centers, as well as a local non-governmental organization promoting public scientific literacy. This project will further facilitate knowledge transfer between US and international partners by conducting a formal interlaboratory comparison of analytical methods, co-organizing two workshops for US and Indian undergraduate students, and developing K-12 educational outreach. This project will also support two early career faculty and promote the full participation of two graduate and two undergraduate students who will be recruited through programs designed to broaden participation of traditionally underrepresented groups in the geosciences.Orogenic syntaxes are regions of high crustal strain that accommodate the transition from convergence to strike-slip motion at the margins of an indenting plate collision. For several decades, Tectonics research has focused on strain partitioning within the indented plate of a collision zone, this focus has neglected the important influence of strain partitioning within the indenting plate, and in particular, the role of sliver terrane accretion on the evolution of indenter corner fault intersections. Observations from both the eastern Himalayan and Alaskan orogens suggest that the accretion of sliver terranes along transform faults flanking collision zones can lead to a ‘double collision’ where a once-stable fault intersection changes into an unstable triple junction, altering the kinematics of indenter corner fault systems and the pattern of upper plate deformation. To evaluate the broader influence of terrane accretion on collisional orogenesis, this 3-year project will reconstruct the kinematic history of a triple junction in the eastern Himalayan indenter corner. This project focuses on the kinematic history of the Noa Dihing Fault, a key structure at the center of the eastern Himalaya indenter corner that juxtaposes the Indian-Eurasian collision zone with the subduction zone between Indian and the Burma Terrane, as well as the Burma-Eurasia transform zone. This project will constrain the late Cenozoic kinematic history of the Noa Dihing Fault through a combination of field mapping, zircon U-Pb geochronology, fault kinematic analysis, and thermo-kinematic modeling of apatite fission-track, zircon fission track and 40Ar/40Ar thermochronology in the Noa Dihing Fault hanging wall. Testing this hypothesis that sliver terranes concentrate strain within continental indenter corners will help to explain differences in structural style between indenter corners in the same tectonic setting (e.g. differences in the curvature between the eastern and western Himalayan indenter corners) and also relate similarities between indenter corners in different tectonic settings (e.g. southern Alaska and the eastern Himalaya). This is a new way of thinking about indenter tectonics and could provide a complementary perspective that builds further helps to link research in Alaskan and Himalayan orogens.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.

大陆构造板块的碰撞产生了地球上一些最高的地形、最深的沉积盆地和最有可能发生大地震的地方。为了解释这些独特的板块边界如何演变，地质学家通常模拟刚性构造板块之间的碰撞并产生凹痕。相反，最近对喜马拉雅山东部和阿拉斯加的观测结果表明，自然界中的凹陷板块并不完全是刚性的，特别是当它们包含先前碰撞中积累的地壳块时。这意味着活动断层系统也可能在凹陷板块和凹陷板块内变形（并产生地震），从而改变地球科学家理解大陆碰撞带内板块边界断层的方式。喜马拉雅山东部的一个天然实验室，用于测试先前的增生地体从根本上改变了碰撞带边缘的活动断层系统这一假设。这项研究将解决 2018 年概述的三大挑战。 NSF 构造学研究社区愿景文件，将加强美国科学家和印度多所大学和研究中心的研究人员以及促进公众科学素养的当地非政府组织之间的国际联系。该项目将进一步促进美国和国际之间的知识转移。该项目还将支持两名早期职业教师，并促进两名研究生和两名研究生的全面参与。将通过旨在传统上在地球科学中代表性不足的群体的参与。造山构造是地壳高应变区域，在凹进板块碰撞的边缘适应从汇聚到走滑运动的过渡，几十年来，构造学研究一直集中在构造内部的应变分配。碰撞带的凹痕板，这种关注忽略了凹痕板内应变分配的重要影响，特别是银地体增生对演化的作用对喜马拉雅造山带东部和阿拉斯加造山带的压头角断层交叉点的观察表明，沿着碰撞带两侧的转换断层的长条地体的增生可能导致“双重碰撞”，其中曾经稳定的断层交叉点转变为不稳定的三重交点，改变压头角断层系统的运动学和上板块变形的模式为了评估地体增生对碰撞造山作用的更广泛影响。为期三年的项目将重建喜马拉雅压头角东部三重交点的运动历史。该项目重点研究诺亚迪兴断层的运动历史，诺亚迪兴断层是喜马拉雅东部压头角中心的一个关键结构，与印度-喜马拉雅山压头角并列。欧亚碰撞带与印度地体和缅甸地体之间的俯冲带以及缅甸-欧亚转换带将制约晚新生代的运动学历史。通过结合实地测绘、锆石 U-Pb 地质年代学、断层运动学分析以及磷灰石裂变径迹、锆石裂变径迹和 Noa Dihing 断层上盘中 40Ar/40Ar 热年代学的热运动学建模，对 Noa Dihing 断层进行了研究。银地体将应变集中在大陆压头角内的这一假设将有助于解释大陆压头角之间结构风格的差异。相同的构造环境（例如喜马拉雅东部和西部压头角之间的曲率差异）以及不同构造环境（例如阿拉斯加南部和喜马拉雅东部）压头角之间的相似性，这是一种思考压头构造的新方法。并可以提供补充视角，进一步帮助将阿拉斯加造山带和喜马拉雅造山带的研究联系起来。该奖项反映了 NSF 的法定使命，并被认为是值得的通过使用基金会的智力优势和更广泛的影响审查标准进行评估来提供支持。