Collaborative Research: Reframing Notions of Wet vs. Dry Subduction: The Search for a Deep Fluid Signature in Subducted Continental Crust Using Coupled O, B, and Fe Isotopes

合作研究：重新定义湿俯冲与干俯冲的概念：使用 O、B 和 Fe 耦合同位素寻找俯冲大陆壳中的深层流体特征

基本信息

批准号：
1822524
负责人：
Catherine Macris
金额：
$ 24.84万
依托单位：
Indiana University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-15 至 2022-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1822524&HistoricalAwards=false
关键词：
Collaborative Research Reframing Notions Wet

项目摘要

Subduction zones represent not only the main mechanism of mass transfer between the Earth's surface and interior, but also the setting for a majority of large earthquakes and a source of significant volcanic activity, both of which have dramatic and direct effects on human civilization. The presence, scale, and nature of fluids in deep portions of subduction zones are undoubtedly important factors in the generation of both earthquakes and magma, and therefore must be identified and characterized. This study will contribute to our current understanding of deep fluids in subduction zones, and potentially establish a new method for studying them. It would also, as the title suggests, reframe notions of wet versus dry subduction, which may open the door to other ideas and methods for studying subduction zone processes. This project will provide training and research opportunities for a diverse group of graduate and undergraduate students. Outreach activities at local GK-12 schools will expose potential future scientists to cutting edge Earth Science.Small volumes of continental crust surrounded by oceanic crust may be subducted to ultrahigh-pressure (UHP) depths and exhumed in the early stages of orogeny. These small, subducted blocks of continental crust can preserve evidence of large-scale, deep subduction fluid metasomatism. This team hypothesizes that the Tso Morari terrane, a young UHP locality in the NW Himalaya, represents a small, early-subducted continental mass that likely experienced metasomatism at UHP in the subduction zone. Recent advances have led to novel isotopic and geochemical proxies to fingerprint the origin of subduction-derived fluids and melts both in exhumed subduction materials and arc magmas. In particular, boron is expected to be enriched in devolatilized fluids and depleted in the corresponding host rocks with boron isotopic values providing a sensitive indication of the extent of devolatilization. Additionally, iron isotope systematics are emerging as a potentially powerful tracer of the nature of slab derived fluids. This project will combine these novel proxies with the more established and traditional tracers of subduction fluids, including oxygen isotopes, thermodynamic and fluid modeling, bulk-rock geochemistry, ferrous/ferric iron ratios on a suite of UHP rocks and associated ophiolite/melange from the Tso Morari.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.

俯冲带不仅代表了地球表面和内部之间传质的主要机制，还代表了大多数大地震的设置和重要的火山活动来源，这两者都对人类文明具有巨大的直接影响。俯冲区域深层地区流体的存在，规模和性质无疑是地震和岩浆产生的重要因素，因此必须确定和表征。这项研究将有助于我们当前对俯冲带中深流体的理解，并有可能建立一种研究它们的新方法。正如标题所暗示的那样，它还将重新构造湿俯冲与干式俯冲的概念，这可能为研究俯冲带过程的其他想法和方法打开了大门。该项目将为各种研究生和本科生提供培训和研究机会。当地GK-12学校的外展活动将使潜在的未来科学家接触到尖端的地球科学。被海壳包围的大陆地壳的小批量可能会被俯冲到超高压（UHP）深度，并在造型的早期阶段发掘。这些小的大陆壳块块可以保留大规模，深俯冲流体交代的证据。该团队假设TSO Morari Terrane是NW喜马拉雅省的年轻UHP地区，代表了一个小型，早期的大陆质量，可能在俯冲带的UHP中经历了交代性。最近的进步导致了新型的同位素和地球化学代理，在俯冲材料和弧形岩浆中均具有俯冲衍生的流体和融化的起源。特别是，预计硼将富集在去脱脂的液体中，并在具有硼同位素值的相应宿主岩石中耗尽，从而提供了敏感的devolatilization范围。另外，铁同位素系统正在成为平板衍生流体本质的潜在强大示踪剂。该项目将将这些新颖的代理与俯冲液的更具成熟和传统的示踪剂相结合，包括氧同位素，热力学和流体建模，热力学和流体建模，散装岩石地球化学，在UHP岩石套件上的us of tso和Merange y Morange and Morange and tso and satfory n s n s n s n s n s n s.利用基金会的知识分子和更广泛的影响审查标准。