Collaborative Research: Rodingites as Recorders of Tectonic Processes from the Seafloor to Convergence: A case study of the Dun Mountain Ophiolite Belt

合作研究：罗丁岩作为从海底到聚合的构造过程的记录者：以敦山蛇绿岩带为例

• 批准号: 2147570
• 负责人: Jaime Barnes
• 金额: $ 40.9万
• 依托单位: University of Texas at Austin
• 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=2147570&HistoricalAwards=false
• 关键词: Collaborative; Research; Rodingites; Recorders; Tectonic

The hydration of ultramafic rock (called serpentinization) is a fundamental Earth process that influences the rheology of materials and thus how rocks deform, localize strain, and behave seismically. In addition, serpentinization affects geochemical cycling of key elements such as hydrogen, carbon, and sulfur and therefore influenced the evolution of life. Serpentinization is a widespread process most common at the boundaries of tectonic plates. By understanding the conditions (pressure, temperature, deformation, fluid source) and timing of serpentinization, one can place constraints on major tectonic processes occurring at plate boundaries, such as continental rifting, seafloor spreading, subduction, and strain-localization along strike-slip faults. Unfortunately, determining the pressure-temperature-deformation-fluid-time (P-T-d-f-t) histories of serpentinites themselves has long been challenging. This research will determine the P-T-d-f-t histories of rodingites, rocks associated with serpentinites, as a proxy to place constraints on the timing and conditions of serpentinization in order to interpret the tectonic evolution of plate boundaries. This multi-disciplinary project invokes a tiered mentorship structure from full professors to assistant professors to graduate and undergraduate students. This work will support student education and scientific training by partial funding of multiple students at the graduate (Ph.D. and M.S.) and undergraduate levels, as well as a minority student summer internship program. The research will determine the conditions and timing of rodingitization (and associated serpentinization) of the Dun Mountain Ophiolite Belt in the Nelson region of New Zealand to place constraints on the tectonic evolution of the ophiolite. Despite New Zealand being the type locality of rodingites, limited work has focused on their tectonic setting of formation with interpretations ranging from formation on the seafloor to post-emplacement on land due to either crustal fluids or fluid focusing along late faults. The research will test the hypothesis that the rodingites from the Dun Mountain Ophiolite formed during seafloor hydrothermal alteration or in the overlying forearc mantle wedge during the mid-Permian. In contrast, the rodingites from associated serpentinite mélanges formed during subduction and/or exhumation via interaction with slab-derived fluids along the plate interface and will be of slightly younger age. The research will also test the hypothesis that minimal rodingitization occurred post-emplacement. The research will determine the conditions and timing of rodingitization of the Dun Mountain Ophiolite Belt by using phase equilibria modeling to determine the P-T conditions of rodingitization, combined with the new and novel techniques of U-Pb geochronology and Ca and Sr isotope composition of andradite garnet in the rodingites to determine the timing of and fluid source responsible for rodingitization, respectively. Field structural and microstructural data will help in evaluation of timing of rodingitization, particularly with multiple generations of rodingites related to different tectonic fabrics (e.g., preservation of undeformed igneous textures; penetrating fabric within both the rodingite and host serpentinite). As the applications to U-Pb geochronology and Ca and Sr isotope composition to rodingites are limited, the research team will first reconstruct the tectonic histories from well-known localities on the seafloor (fast-spreading ridge and passive rifted margin) and in the Western Alps (exhumed subducted metamorphic terrane) to provide proof of concept. They will then determine when rodingitization within the Dun Mountain Ophiolite Belt occurred and how these metasomatic event(s) record the tectonic history of the Dun Mountain Ophiolite Belt.Funding for this project is provided by NSF EAR Tectonics and OCE Marine Geology and Geophysics Programs.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.

超镁铁质岩石的水合（称为蛇纹石化）是一个基本的地球过程，它影响材料的流变学，从而影响岩石如何变形，局部应变和地震行为。此外，蛇形化会影响关键因素（例如氢，碳和硫）的地球化学循环，因此影响了生命的演变。蛇纹石化是在构造板的边界上最常见的广泛过程。通过了解条件（压力，温度，变形，流体源）和蛇形化的时机，可以将约束放在板块边界处发生的主要构造过程，例如连续骑行，海底扩散，俯冲，俯冲和沿进攻 - 沿进攻 - 滑移断层的应变平衡化。不幸的是，长期以来，确定蛇丁替矿的历史（p-t-t-f-t-t）本身一直受到挑战。这项研究将确定Rodingites的P-T-F-T-T历史，与蛇纹石相关的岩石，作为对蛇纹石化的时机和条件的约束，以解释板边界的构造演化。这个多学科的项目援引了从完整教授到助理教授到研究生和本科生的分层心态结构。这项工作将通过对研究生（博士学位和M.S.）和本科级别的多个学生进行部分资助以及少数学生暑期实习计划的部分资助来支持学生的教育和科学培训。这项研究将确定新西兰尼尔森地区的Dun Mountain Ophiolite带的覆盖（以及相关的蛇纹石化）的条件和时机，以对蛇绿岩的构造演化放置约束。尽管新西兰是罗丁矿的类型，但有限的工作集中在其形成的构造环境上，其解释范围从海底的地层到沿着末期断层的地下液体或液体聚焦，从海底上的地层到土地后的铺面。这项研究将检验以下假设：在海底热液改变期间形成的邓山山胶质的玫瑰岩或在permian期间的上层前臂地幔楔中形成的假设。相反，通过与沿板界面的平板衍生的流体相互作用，在俯冲和/或挖掘过程中形成的相关蛇状泥的覆盖物，年龄稍小。这项研究还将检验以下假设：造成后发生最小化的脂化。这项研究将通过使用相等的模型来确定Dun Mountain Mountain Fermitiation的条件和时机来确定啮齿动物炎的P-T条件，并结合U-PB地球人数的新技术和新型技术以及在啮齿动物中的CA和SR同位素组成和RADITE GARNET的组成，以确定和流体负责性的降压源的时间。田间结构和微观结构数据将有助于评估啮齿动物炎的时间，特别是与不同的构造织物相关的多个棒脂地（例如，保存未呈现的火成岩纹理；在玫瑰丁岩和宿主serpentinite中都穿透织物）。由于对Rodingites的U-PB地质学以及CA和SR同位素组成的应用是有限的，因此研究团队将首先从海底著名地区（快速散布的山脊和被动的裂口和被动的裂开边缘）重建构造历史，并在西部阿尔卑斯山（杂种型的terrane terrane）中，以提供概念的证明。然后，他们将确定在邓山山胶石皮带内发生啮齿动物何时发生啮齿动物，以及这些转移事件如何记录Dun Mountain Mountain Ophiolite腰带的构造历史。该项目的资金由NSF耳朵构造和OCE Marine Geology and Geophysics计划提供，这些奖项反映了NSF的稳定范围。 标准。