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大的大地震可能性。为了解释这些独特的板块边界是如何演变的，地质学家通常会模拟刚性构造板块与较弱的构造板块碰撞并凹陷的碰撞。相反，来自喜马拉雅东部和阿拉斯加东部的最近观察表明，自然界中的凹陷板块并不完全是刚性的，特别是当它们包含因过去地质历史上的碰撞而形成的地壳块体碎片时。这意味着，活动断裂系统也可能在凹陷板块和凹陷板块内变形(并产生地震)，从而改变地质学家对大陆碰撞带内板块边界断层的理解。该项目将研究喜马拉雅东部的复杂构造环境，这是一个天然实验室，用于验证先前吸积的地体从根本上改变了碰撞带边缘的活动断裂系统的假设。这项研究将解决2018年NSF社区构造研究愿景文件中概述的三大挑战，并将加强美国科学家与印度多所大学和研究中心以及当地一个促进公众科学素养的非政府组织之间的国际联系。该项目将通过对分析方法进行正式的实验室间比较，共同为美国和印度的本科生举办两个研讨会，以及发展K-12教育外展，进一步促进美国和国际合作伙伴之间的知识转移。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本科生的充分参与，他们将通过旨在扩大传统上代表性不足的群体参与地球科学的方案而招募。造山构造是地壳高度应变的区域，适应在凹陷板块碰撞边缘从会聚到走滑运动的过渡。几十年来，构造学的研究主要集中在碰撞带凹陷板块内的应变分配，而忽略了凹陷板块内应变分配的重要影响，特别是银质地体在凹陷拐角断层交汇处演化中的作用。东喜马拉雅造山带和阿拉斯加造山带的观测表明，沿碰撞带两侧的转换断层堆积的银色地体可导致一次稳定的断层交汇处变成不稳定的三联点，从而改变了凹角断层系统的运动学和上板块变形的模式。为了评估地体吸积对碰撞造山作用的广泛影响，这项为期3年的项目将重建喜马拉雅东部凹陷拐角三个结点的运动学历史。该项目重点研究了诺阿迪兴断裂的运动学历史，这是喜马拉雅东部凹陷角中心的一个关键构造，将印度-欧亚碰撞带与印度和缅甸地体之间的俯冲带以及缅甸-欧亚转换带并列在一起。该项目将通过野外填图、锆石U-Pb年代学、断裂运动学分析以及诺亚第兴断裂上盘磷灰石裂变径迹、锆石裂变径迹和40Ar/40Ar热年代学的热运动学模拟相结合的方法，约束诺亚第兴断裂晚新生代的运动学历史。验证这一假设，即银色地体在大陆凹角集中应变，将有助于解释相同构造背景下凹角之间的构造样式差异(例如，东、西喜马拉雅凹角之间的曲率差异)，并将不同构造背景(例如，阿拉斯加南部和东喜马拉雅)的凹角之间的相似性联系起来。这是一种思考压痕构造的新方法，并可能提供一个补充视角，进一步有助于将阿拉斯加和喜马拉雅造山带的研究联系起来。这一奖项反映了NSF的法定使命，并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，被认为值得支持。