Collaborative Research: Decoding thermal and magmatic history of mafic and ultramafic rocks through systematic studies of cation diffusion in pyroxene

合作研究：通过系统研究辉石中的阳离子扩散来解码镁铁质和超镁铁质岩石的热和岩浆历史

• 批准号: 2147603
• 负责人: Daniele Cherniak
• 金额: $ 15.05万
• 依托单位: SUNY at Albany
• 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: 2022-02-15 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2147603&HistoricalAwards=false
• 关键词: Collaborative; Research; Decoding; thermal; magmatic

Orthopyroxene and clinopyroxene are two major rock-forming minerals in the Earth’s upper mantle and lower crust. Major and trace element compositions of the pyroxenes have been widely used to infer thermal and magmatic histories experienced by pyroxene-bearing rocks. A common feature of pyroxene in natural rocks is the presence of exsolution lamellae. There is no model for cation diffusion in and through pyroxene in the presence of exsolution lamellae, which hinders the interpretation of thermal history of pyroxene-bearing rocks. The focus of this collaborative study is Al, Ca, Zr, and Hf diffusion in pyroxene. The project consists of three main tasks: (1) theoretical and numerical studies of the role of exsolution lamellae on cation diffusion in pyroxene; (2) experimental studies of Al, Ca, Zr, and Hf diffusion in pyroxene; and (3) geochemical applications. The outcome shall be a set of models for diffusive mass transfer across pyroxene grains that have exsolution lamellae. These diffusion models are general and can also be used to study chemical and mechanic properties of composite materials outside the field of petrology and geochemistry. Al, Ca, Zr and Hf diffusion coefficients will then be applied to develop generalized mass transfer models that can be used to quantify rare earth element (REE) and high-field strength element (HFSE) fractionation during disequilibrium melting along a mantle adiabat followed by subsolidus re-equilibration. New models for closure temperatures of the Ca-in-opx thermometer and the Al-in-opx thermometer will be developed. These new models will be used to study the distribution and fractionation of REE and HFSE in pyroxenes in peridotites from different tectonic settings. The broader impacts of the proposed work will focus on graduate and undergraduate training and support of a highly productive female scientist. Models for diffusion in and through laminates to be developed in this proposed work are general and can be used to study chemical and mechanic properties of composite materials in fields outside Earth science. Major and trace element zoning in pyroxene has often been observed in mafic and ultramafic rocks, which may provide important clues to the thermal and magmatic histories experienced by the pyroxene-bearing rocks. A common feature of pyroxene in natural rocks is the presence of exsolution lamellae. Although significant progress has been made in quantifying rare earth element (REE) and high field strength element (HFSE) diffusion in pyroxene, very little is known about Al diffusion in pyroxene. There are no published data for Ca diffusion in orthopyroxene and no model for cation diffusion in and through pyroxene in the presence of exsolution lamellae. The focus of this collaborative study is Al, Ca and HFSE diffusion and distribution in pyroxene and their geochemical applications. The project consists of three main Tasks: (1) theoretical and numerical studies of the role of exsolution lamellae on cation diffusion in pyroxene; (2) experimental studies of Al, Ca, Zr, and Hf diffusion in pyroxene; and (3) geochemical applications. The majority of the diffusion experiments will be conducted at 1-atm pressure. The potential effects of pressure on Al, Ca Zr, and Hf diffusion in pyroxene are not known, but some higher-pressure experiments will be conducted. Diffusion profiles of Al in experimental charges will be measured with the 27Al(p,gamma)28Si nuclear reaction. Diffusion profiles of Ca, Zr and Hf will be measured with Rutherford Backscattering Spectrometry. The outcome of Task 1 is a set of microscale and macroscale models for diffusive mass transfer across pyroxene grains that have exsolution lamellae. These diffusion models are general and can also be used to study chemical and mechanic properties of composite materials outside the field of petrology and geochemistry. Together with published partitioning and diffusion data, Al, Ca, Zr and Hf diffusion coefficients from Task 2 will be used to develop generalized mass transfer models that can be used to quantify REE and HFSE fractionation during disequilibrium melting along a mantle adiabat followed by subsolidus re-equilibration. As part of Task 3, new models for closure temperatures of the Ca-in-opx thermometer and the Al-in-opx thermometer will be developed. These new models will be used to study the distribution and fractionation of REE and HFSE in pyroxenes in peridotites from different tectonic settings. The broader impacts of the proposed work will focus on human resources, which include graduate and undergraduate training and support of a highly productive female scientist. The proposed work will constitute a major part of the graduate student’s PhD thesis. The project will provide laboratory analytical and computer modeling experiences for undergraduate students and research opportunities for senior thesis projects. Models for diffusion in and through laminates to be developed in this proposed work are general and can be used to study chemical and mechanic properties of composite materials in fields outside Earth science.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.

邻苯二甲烯和斜氧烯是地球上地幔和下层地壳中的两个主要岩石形成矿物。辉石的主要和微量元素组成已被广泛用于推断含辉石的岩石经历的热和岩浆历史。辉石在天然岩石中的一个共同特征是存在叶片的存在。在存在层状薄片的情况下，没有阳离子扩散和通过辉石的模型，这阻碍了含辉石岩石的热史的解释。这项协作研究的重点是辉石的AL，CA，ZR和HF差异。该项目由三个主要任务组成：（1）关于层状薄片对辉石阳离子差异的作用的理论和数值研究； （2）Al，CA，ZR和HF差异的实验研究； （3）地球化学应用。结果应是跨辉石晶粒的一组模型，这些模型具有较高的层状。这些差异模型是一般的，也可以用于研究岩石学和地球化学领域之外的复合材料的化学和机械性能。然后，将应用AL，CA，ZR和HF扩散系数来开发广义传质模型，这些模型可用于沿着地幔Adiabat的不平衡融化期间，用于量化稀土元素（REE）和高视野强度元素（HFSE）分馏，然后进行子甲甲基甲甲基甲甲基甲甲基的重新平衡。将开发用于CA-IN-OPX温度计和AL-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN型号。这些新模型将用于研究来自不同构造环境中橄榄岩中辉石中REE和HFSE的分布和分馏。拟议工作的更广泛的影响将集中于研究生和本科培训以及高产女性科学家的支持。在这项拟议的工作中开发的扩散和通过变薄的模型是一般的，可用于研究地球科学以外的田野中复合材料的化学和机械性能。在辉石和超镁铁质岩石中经常观察到辉石中的主要和痕量元件分区，这可能为含有辉石的岩石所经历的热和岩浆历史提供了重要的线索。辉石在天然岩石中的一个共同特征尽管在量化辉石中的稀土元素（REE）和高场强元（HFSE）扩散方面取得了重大进展，但对于辉石中的Al扩散知之甚少。在异氧化二烯二甲苯和通过辉石的存在下，没有公开的数据在异耐氧烯中进行CA扩散的数据。这项协作研究的重点是辉石及其地球化学应用中的AL，CA和HFSE扩散和分布。该项目由三个主要任务组成：（1）关于浮力层叶片在阳离子扩散中的作用的理论和数值研究； （2）Al，Ca，Zr和HF扩散在辉石中的实验研究； （3）地球化学应用。大多数扩散实验将以1-ATM压力进行。压力对辉石对Al，Ca ZR和HF差异的潜在影响尚不清楚，但是将进行一些高压实验。 AL在实验电荷中的扩散谱将通过27AL（P，Gamma）28SI核反应进行测量。 CA，ZR和HF的扩散曲线将通过Rutherford反向散射光谱法测量。任务1的结果是一组显微镜和宏观基督模型，用于跨层状薄片的层状晶粒不同传质。这些差异模型是一般的，也可以用于研究岩石学和地球化学领域之外的复合材料的化学和机械性能。与已发表的分区和扩散数据一起，任务2的AL，CA，ZR和HF差异系数将用于开发广义传质模型，这些模型可用于沿地幔Adiabat沿二动能融化期间量化REE和HFSE分级分级，然后再进行子宫底层重新平衡。作为任务3的一部分，将开发用于CA-IN-IN-OPX温度计和AL-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-IN-MY模型。这些新模型将用于研究来自不同构造环境中橄榄岩中辉石中REE和HFSE的分布和分馏。拟议工作的更广泛的影响将集中在人力资源上，其中包括研究生和本科培训以及对高产的女科学家的支持。拟议的工作将构成研究生的博士学位论文的重要组成部分。该项目将为本科生提供实验室分析和计算机建模经验，并为高级论文项目提供研究机会。在这项拟议的工作中要开发的激光和通过激光扩散的模型是一般的，可用于研究地球科学以外领域中复合材料的化学和机械性能。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响来审查标准，通过评估来诚实地支持。