Collaborative Research: Experimental Study of Mineral-Fluid Fractionation of Non-Traditional Isotopes (Fe, Cu, Zn, S) with Implications for Seafloor Hydrothermal Systems

正在进行许多海底热液喷口系统的经验研究和越来越多的生物地球化学研究，以利用非常规稳定同位素（即铁、锌、铜和硫等重元素的同位素）研究各种矿物学和生物过程。为了使这些实证研究获得定量和预测结果，必须知道这些同位素的分馏因子。然而，目前还没有实验工作来推导这些系数和参数。这项研究建立在为期一年的概念验证研究的基础上，表明分馏在这些系统中以系统的方式发生。新项目考察了温度、流体化学和反应速率对高温高压下硫化物矿物和流体之间非传统稳定同位素（Fe、Cu、Zn、S）分馏的影响。这项工作将包括相分离实验，以评估流体化学在蒸汽和盐水之间非传统稳定同位素分馏中的作用。它将在平衡实验中使用同位素示踪剂来观察反应过程，并观察同位素系统如何响应反应速率和机制。均相和非均相系统的硫同位素交换也将进行实验测试。这项工作的更广泛影响包括通过发展动力学和分馏因素为科学建立基础设施，这些因素对于预测含铁、铜、锌、锌矿物稳定性的理论模型的发展至关重要。影响还包括研究生和本科生参与最先进的水岩相互作用实验研究，并参与EPSCOR州（路易斯安那州）一所机构的早期职业PI。

Many empirical studies of hydrothermal vent systems on the seafloor and an increasing number of biogeochemical studies are being carried out to look at various mineralogical and biological processes using unconventional stable isotopes (i.e., those of heavy elements such as iron, zinc, copper, and sulfur). To allow quantitative and predictive results of these empirical studies, fractionation factors of these isotopes must be known. However, at present, no experimental work to derive these coefficients and parameters have been carried out. This research builds off a one-year proof-of-concept study to show that fractionation occurs in these systems in a systematic way. The new project examines the effects of temperature, fluid chemistry, and reaction rate on the fractionation of non-traditional stable isotopes (Fe, Cu, Zn, S) between sulfide minerals and fluids at elevated temperatures and pressures. The work will include phase separation experiments to assess the role of fluid chemistry on non-traditional stable isotope fractionation between vapor and brine. It will use isotope tracers in equilibrium experiments to look at reaction progress and to see how isotope systematics respond to reaction rates and mechanisms. Sulfur isotope exchange for homogeneous and heterogeneous systems will also be tested experimentally. Broader impacts of the work include building fundamental infrastructure for science via the development of kinetic and fractionation factors that are essential for the development of theoretical models for predicting stabilities of minerals containing Fe, Cu, Zn, and S. Impacts also include the engagement of graduate and undergraduate students in state-of-the-art experimental studies of water-rock interaction and the involvement of an early career PI from an institution in an EPSCOR State (Louisiana).