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

目前正在对海底热液喷口系统进行许多经验研究，并开展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、铜和硫等重元素的稳定同位素)研究各种矿物学和生物过程。为了获得这些经验研究的定量和预测性结果，必须知道这些同位素的分馏系数。然而，目前还没有进行推导这些系数和参数的实验工作。这项研究建立在为期一年的概念验证研究的基础上，以表明分馏在这些系统中以系统的方式发生。该新项目考察了温度、流体化学和反应速度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、铜、锌、S)分馏的影响。这项工作将包括相分离实验，以评估流体化学对蒸汽和盐水之间非传统稳定同位素分馏的作用。它将在平衡实验中使用同位素示踪剂来观察反应过程，并了解同位素系统学如何对反应速度和机制做出反应。还将对均相和非均相体系的硫同位素交换进行实验测试。这项工作的广泛影响包括通过开发动力学和分馏因子为科学建立基础设施，这些因素对于开发预测含铁、铜、锌和硫矿物稳定性的理论模型至关重要。影响还包括研究生和本科生参与最先进的水-岩石相互作用实验研究，以及来自EPSCoR州(路易斯安那州)一所机构的早期职业PI的参与。

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).