Collaborative Research: Do subduction‐complex metamorphic rocks record the thermal evolution of a subduction zone or periods of anomalous tectonic activity? Baja California

合作研究：俯冲复杂变质岩是否记录了俯冲带的热演化或异常构造活动的时期？

• 批准号: 2127195
• 负责人: Robert Holder
• 金额: $ 34.05万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 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: 2022-09-01 至 2025-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2127195&HistoricalAwards=false
• 关键词: Collaborative; Research; Do; subduction; complex

A fundamental aspect of Earth’s plate tectonic system—the movement of Earth’s rigid outer plates—is subduction: the sinking of oceanic crust down into Earth’s interior along large faults. The largest earthquakes, most volcanic hazards, the locations of mountain belts, many critical metal deposits, the existence of the continents themselves, and the balancing of Earth’s climate over geological time are all ultimately controlled by the process of subduction. Understanding subduction is thus key to understanding many aspects of Earth science. However, studying subduction is difficult because it is happening deep below Earth’s surface and occurs over millions of years. The purpose of this study is to examine rocks that have been brought back to Earth’s surface from an ancient subduction zone; these rocks and the minerals they contain provide a “window” into the chemical and physical processes that occur in subduction zones. Detailed observations of these rocks will be used to test competing hypotheses about how subduction zones operate. In addition to this scientific goal, this project contributes to important societal outcomes by supporting the research program of an early career researcher and by providing educational opportunities, professional development, and mentoring for undergraduate students, graduate students, and post-graduate researchers in an important STEM discipline through classroom study, fieldwork, laboratory work, and professional conferences. Finally, this project fosters international collaboration and strengthens ties between the academic systems of the USA and Mexico.The specific goal of this project is to quantify the pressure–temperature–time histories of amphibolite, blueschist, and eclogite from Mesozoic subduction complexes in the Baja California peninsula, Mexico, by using state-of-the-art thermobarometry and petrochronology. This location in Mexico was chosen for the research due to the outstanding exposure of these important rock types and the unique geological history that brought deeply subducted rocks back to the Earth’s surface for direct investigation. These metamorphic rocks occur as blocks in mélange and coherent units on the Vizcaíno peninsula (structurally beneath the c. 220 Ma Vizcaíno ophiolite) and Cedros Island (structurally beneath the c. 170 Ma Cedros ophiolite). The project will evaluate: (1) the evolution of subduction zone thermal structure with time; and (2) the history, processes, and potential tectonic linkages among metamorphism, exhumation, and ophiolite generation. Project results will be used to test proposed models for subduction initiation and subsequent evolution as well as the relationships between exhumation of metamorphic rocks from subduction zones and regional tectonic changes.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.

地球板块构造系统的一个基本方面--地球坚硬的外部板块的运动--是俯冲：海洋地壳沿着沿着大断层下沉到地球内部。最大的地震，大多数火山灾害，山脉带的位置，许多重要的金属矿床，大陆本身的存在，以及地质时期地球气候的平衡，最终都受到俯冲过程的控制。因此，理解俯冲是理解地球科学许多方面的关键。然而，研究俯冲是困难的，因为它发生在地球表面深处，发生在数百万年前。这项研究的目的是检查从古代俯冲带带回地球表面的岩石;这些岩石及其所含的矿物为俯冲带发生的化学和物理过程提供了一个“窗口”。对这些岩石的详细观察将被用来检验关于俯冲带如何运作的相互竞争的假设。除了这一科学目标，该项目通过支持早期职业研究人员的研究计划，并通过课堂学习，实地考察，实验室工作和专业会议为重要的STEM学科的本科生，研究生和研究生研究人员提供教育机会，专业发展和指导，为重要的社会成果做出贡献。最后，该项目促进了国际合作，加强了美国和墨西哥学术体系之间的联系。该项目的具体目标是通过使用最先进的热压法和岩石年代学，量化墨西哥下加利福尼亚半岛中生代俯冲杂岩中角闪岩、蓝片岩和榴辉岩的压力-温度-时间历史。之所以选择墨西哥的这个地点进行研究，是因为这些重要岩石类型的突出暴露和独特的地质历史，使深俯冲岩石回到地球表面进行直接调查。这些变质岩以混杂岩块和相干单元的形式出现在维兹凯诺半岛上（结构上位于C. 220 Ma Vizcaíno蛇绿岩）和Cedros岛（结构上位于c. 170 Ma Cedros蛇绿岩）。该项目将评价：（1）俯冲带热结构随时间的演化;（2）变质作用、折返作用和蛇绿岩生成之间的历史、过程和潜在的构造联系。项目结果将用于测试俯冲起始和后续演化的拟议模型，以及俯冲带变质岩折返与区域构造变化之间的关系。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。