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: 2319475
• 负责人: Paul Betka
• 金额: $ 26.57万
• 依托单位: Western Washington University
• 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=2319475&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一些最高的地形，最深的沉积盆地，以及地球上发生大地震的最高可能性。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一个刚性构造板块与一个较弱的构造板块碰撞并凹陷的碰撞。相反，最近对喜马拉雅山东部和阿拉斯加的观测表明，自然界中的锯齿状板块并不完全是刚性的，特别是当它们包含地质历史中先前碰撞所产生的地壳块体时。这意味着活动断层系统也可能在锯齿状板块和锯齿状板块内变形（并产生地震），改变了地球科学家对大陆碰撞带内板块边界断层的理解。该项目将研究东喜马拉雅的复杂构造环境，这是一个天然实验室，可用来检验先前的增生岩从根本上改变碰撞区边缘的活动断层系统这一假设。这项研究将解决2018年NSF构造学研究社区愿景文件中概述的三个重大挑战，并将加强美国科学家与印度多所大学和研究中心的研究人员以及当地非政府组织之间的国际联系，促进公众科学素养。该项目将通过对分析方法进行正式的实验室间比较，为美国和印度的本科生共同组织两个研讨会，以及发展K-12教育推广，进一步促进美国和国际合作伙伴之间的知识转移。该项目还将支持两个早期的职业教师，并促进两个研究生和两个本科生的充分参与，他们将通过旨在扩大传统上代表性不足的群体在地球科学的参与计划招募。造山构造带是地壳应变高的地区，适应从收敛到走滑运动的边缘缩进板块碰撞的过渡。几十年来，构造学的研究主要集中在碰撞带的压痕板内的应变分配，忽略了压痕板内应变分配的重要影响，特别是银屑增生对压痕角断层交叉演化的作用。从东喜马拉雅和阿拉斯加造山带的观测表明，沿沿着转换断层碰撞区两侧的银屑堆积可能导致“双重碰撞”，其中一次稳定的断层交叉变为不稳定的三重连接，改变了压痕角断层系统的运动学和上板块变形的模式。为了评估更广泛的影响，碰撞造山作用，这个为期3年的项目将重建在喜马拉雅山东部压痕角的三重连接的运动学历史。该项目的重点是Noa Dihing断层的运动学历史，这是喜马拉雅东部凹陷角中心的一个关键结构，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。该项目将通过野外测绘、锆石U-Pb地质年代学、断层运动学分析以及Noa Dihing断层上盘中磷灰石裂变径迹、锆石裂变径迹和40 Ar/40 Ar热年代学的热运动学建模来约束Noa Dihing断层的晚新生代运动学历史。检验这一假设，即银屑集中应变大陆压痕角将有助于解释在相同的构造环境中的压痕角之间的结构风格的差异（例如，在东部和西部喜马拉雅压痕角之间的曲率的差异），也涉及在不同的构造环境中的压痕角之间的相似性（例如，阿拉斯加南部和喜马拉雅东部）。这是一种关于压头构造的新思维方式，可以提供一个补充的视角，进一步帮助建立阿拉斯加和喜马拉雅造山带的研究联系。该奖项反映了NSF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。