Collaborative Research: A Quantitative Study of Reaction Pathways in Oceanic Serpentinites

海底地幔岩石在海水作用下的蚀变（称为蛇纹岩化）是一个广泛存在的过程。它影响全球化学循环、地震潜力，甚至可能影响生命的起源。然而，蛇纹石化的过程仍然知之甚少。这项工作将进行实验室实验，以便更好地了解蛇纹石化的潜在过程。研究结果将改进模型，使科学家能够更好地解释地幔岩石和流体成分的变化。该项目为学生提供地质海洋学、岩石学和水地球化学方面的培训。为了扩大对科学的参与，研究人员将让来自代表性不足的少数民族的本科生参与这个项目。学生将接受项目设计、样本分析、数据解释和结果展示方面的培训。该项目的成果将通过开放获取手稿、国际会议和讲习班以及研讨会和教学广泛传播。据推测，构成地幔岩石的矿物的不同溶解速率对控制地幔岩石中元素的通量起决定性作用，从而控制次生（热液）矿物形成事件的时间，而次生（热液）矿物形成事件决定了岩石物理性质和喷口流体组成的时间演化。为了验证这一假设，本工作旨在通过将化学、同位素和定量矿物学分析与理论建模相结合，系统地探索蚀变地幔岩石中记录的化学反应的演替。部分蚀变的地幔岩石的化学成分和矿物学图将用于重建地幔矿物的原始比例。通过比较新鲜岩石和反应岩石的矿物丰度，可以推断出相对溶解速率和化学通量。为了重建化学反应的顺序，矿物的丰度将与蚀变的总体程度共同记录。以前的研究结果将用于确定温度对溶解-沉淀反应序列的影响。这项研究的分析结果将为理论模型提供信息，这些模型将考虑岩石成分、蚀变温度、表面积和矿物的不同溶解速率。通过系统地改变单个输入参数，这些模型将与岩石记录相匹配。然后，这些模型将提供与岩石成分、蚀变温度和矿物组合的特定组合相关的流体成分演化的详细信息。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The alteration of seafloor mantle rocks by seawater (referred to as serpentinization) is a widespread process. It affects global chemical cycles, earthquake potential, and possibly the origin of life. However, the process of serpentinization remains poorly understood. This work will conduct laboratory experiments to enable a better understanding of the underlying processes of serpentinization. The results will improve models and allow scientists to better interpret altered mantle rocks and fluid compositions. This project provides student training in geological oceanography, petrology, and aqueous geochemistry. To broaden participation in science, the researchers will involve undergraduate students from underrepresented minorities in this project. The students will be offered training in project design, sample analysis, data interpretation and presentation of results. Results of this project will be broadly disseminated through open access manuscripts, at international conferences, and workshops, and as well as through seminars, and teaching.It is hypothesized that distinct dissolution rates of minerals that constitute mantle rocks are decisive in controlling the fluxes of elements from the mantle rock and, therefore, in controlling the timing of secondary (hydrothermal) mineral formation events which dictate the temporal evolution of physical rock properties and compositions of vent fluids. To test this hypothesis, this work aims at systematically exploring the succession of chemical reactions recorded in altered mantle rocks by integrating chemical, isotopic, and quantitative mineralogical analyses with theoretical modeling. Chemical compositions, as well as mineralogical maps of partially altered mantle rocks will be used to reconstruct the original proportions of mantle minerals. By comparing mineral abundances of fresh and reacted rocks, relative dissolution rates and chemical fluxes will be inferred. To reconstruct the sequences of chemical reactions, abundances of minerals will be co-registered with the overall extents of alteration. Results from previous studies will be applied to determine the effect of temperature on the succession of dissolution-precipitation reactions. The analytical outcomes of this study will inform theoretical models that will take rock compositions, alteration temperature, surface areas, and distinct dissolution rates of minerals into account. By systematically varying the individual input parameters, these models will be developed that match the rock record. These models will then provide detailed insight on the evolution of fluid compositions associated with specific combinations of rock compositions, alteration temperatures, and mineral assemblages.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.