How Does Mid to Lower Arc Crust Respond to the Transition from Subduction to Collision? Investigation of the Gangdese Orogen Crustal Section

中下弧地壳如何应对从俯冲到碰撞的转变？

• 批准号: 2221618
• 负责人: Wenrong Cao
• 金额: $ 44.97万
• 依托单位: Board of Regents, NSHE, obo University of Nevada, Reno
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2221618&HistoricalAwards=false
• 关键词: How; Does; Mid; Lower; Arc

This project will investigate how the convergence between two tectonic plates influences the structural, thermal, and compositional properties of the continental crust. Understanding how continental crust responds to subduction and collision during plate convergence will provide insights into the hundreds-of-million-of-years history of continental crust evolution and how tectonic and magmatic processes influence the surface topography in major mountain belts. In order to answer this question, the research team will investigate the Gangdese Batholith in southern Tibet that was formed during the prolonged convergence between the Indian and Eurasian plates. The major goals of this project include establishing a cross section through the ancient Gangdese Batholith crust to study how crustal properties (e.g., structures and compositions) change along the vertical (depth) profile. To do this, the researchers will collect rock samples to determine their pressure–temperature histories and investigate how the record preserved within these rocks can be used to constrain the temporal variation of crustal thickness, topographic elevation, and mass transfer processes. The results of this project will help in understanding the evolution of the continental crust that forms the foundation of our habitable planet and how the structure and composition of the crust are shaped by various types of solid earth processes. This project promotes diversity in geosciences, fosters international collaboration between US and Chinese scientists, and supports STEM graduate and undergraduate students and one early-career investigator. This project also aims to increase educational outreach with K-12 students and the broader public via in-person talks and through a popular social media platform. Research results will be disseminated through open-access databases, publications, and international meetings held on both sides of the Pacific, including the Himalayan research community. The Gangdese orogen in southern Tibet, China, is one of the only locations on Earth to study the transition from ocean-continent subduction to continent-continent collision and how such transition affects the construction and evolution of the continental crust. The overall goals of the proposed work are to establish the regional framework of bedrock pressures and the pressure–temperature-time–deformation (P–T–t–D) history across the eastern portion of the orogen. The research team will: (1) systematically collect structural observations and samples from different structural levels exposed in the eastern Gangdese orogen, including less-studied metasedimentary rock exposures; (2) use a variety of novel barometers and petrochronometry techniques to establish P-T-t paths of igneous and metasedimentary rocks; (3) conduct structural and electron backscatter diffraction analyses to quantify finite strain shape, intensity, deformation temperatures, and kinematics of fabrics; and (4) integrate P-T-t-D data and existing crustal thickness data to investigate geological processes operating in the deep Gangdese crust and to investigate how these processes evolve during and after the transition from arc magmatism to collision. The Gangdese orogen provides a unique opportunity to probe how metamorphism, deformation, and crustal flow vary during different tectonic stages, all of which can be extrapolated to active and other ancient continental magmatic orogens to advance our understanding of the evolution of the continental crust. held on both sides of the Pacific, including the Himalayan research community.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.

该项目将研究两个构造板块之间的聚合如何影响大陆地壳的结构、热和成分特性，了解大陆地壳如何响应板块聚合期间的俯冲和碰撞，将为了解数以亿计的构造板块提供见解。 - 大陆地壳演化的多年历史以及构造和岩浆过程如何影响主要山带的地表地形 为了回答这个问题，研究小组将对西藏南部的冈底斯岩基进行调查。该项目的主要目标包括建立古代冈底斯岩基地壳的横截面，以研究地壳性质（例如结构和成分）如何沿垂直（深度）剖面变化。为此，研究人员将收集岩石样本以确定其压力-温度历史，并研究如何利用这些岩石中保存的记录来限制地壳厚度、地形海拔和质量传递过程的时间变化。该项目的研究将有助于了解构成宜居星球基础的大陆地壳的演化，以及各种类型的固体地球过程如何塑造地壳的结构和组成。该项目促进地球科学的多样性，促进国际合作。该项目还旨在通过面对面的会谈和流行的社交媒体平台，扩大与 K-12 学生和更广泛公众的教育联系。研究成果将通过以下途径传播太平洋两岸的开放获取数据库、出版物和国际会议，包括中国西藏南部的冈底斯造山带，是地球上唯一研究海洋-大陆俯冲转变的地点之一。大陆与大陆碰撞以及这种转变如何影响大陆地壳的构造和演化。拟议工作的总体目标是建立基岩压力和压力-温度-时间-变形的区域框架。 （P-T-t-D）造山带东部历史 研究小组将：（1）系统地收集冈底斯造山带东部暴露的不同结构层面的结构观测和样本，包括研究较少的变沉积岩暴露。 (2) 使用各种新型气压计和岩石测时技术建立火成岩和变沉积岩的 P-T-t 路径；(3) 进行结构和电子背散射衍射分析以量化有限应变形状、强度、变形温度和织物运动学；(4) 整合 P-T-t-D 数据和现有地壳厚度数据，研究冈底斯地壳深处的地质过程，并研究这些过程在弧岩浆作用转变期间和之后如何演化。冈底斯造山带提供了一个独特的机会来探索不同构造阶段的变质作用、变形和地壳流动如何变化，所有这些都可以推断为活跃和碰撞。其他古代大陆岩浆造山带，以促进我们对太平洋两岸大陆地壳演化的理解，包括喜马拉雅研究界。该奖项是法定使命，并通过使用基金会的智力价值和评估进行评估，被认为值得支持。更广泛的影响审查标准。