In situ determination of sulfur speciation in fluids at high temperature and pressure at controlled redox conditions: implications for magma degassing and formation of magmatic ore deposits

在受控氧化还原条件下原位测定高温高压流体中的硫形态：对岩浆脱气和岩浆矿床形成的影响

基本信息

批准号：
249781619
负责人：
Professor Dr. Harald Behrens
金额：
--
依托单位：
Institut für Mineralogie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/249781619?language=en
关键词：
situ determination sulfur speciation fluids

项目摘要

Sulfur-bearing gases or fluids are produced in tremendous amounts during degassing of magmas in nature, but are also released during fining of melts in industrial glass production. Since high temperature fluids are often not quenchable, central issue of the proposed project is to study such fluids in situ at high temperature and pressure using Raman spectroscopy as analytical tool. For doing so, we develop a new sapphire-based cell which allows abrupt or continuous changes of pressure at constant temperature, operating at pressures up to 200 MPa and temperatures up to 800°C. Oxygen fugacity (fO2) is a key parameter determining the stability of sulfur species in the fluid. In the experiments the redox conditions will be either pre-adjusted by the loaded fluid components or controlled by adding a specially designed buffer capsule filled with Fe/FeO, Co/CoO, Ni/NiO or other redox pairs. For comparison, the hydrothermal diamond anvil cell technique will be used to study fluids under isochoric conditions at higher pressures and densities. At conditions at which the speciation in the solution is known, these experiments are also aimed at determination of relative Raman scattering cross-sections relevant to this study, and to test the applicability of literature data. In order to facilitate interpretation of the Raman spectra, we want to start with relative simple hydrous systems containing only one sulfur component (e.g., H2SO4, H2S, MgSO4, Na2SO4, Na2S). It is planned to approach more complex magmatic fluids by using combinations of different sulfur sources or source of intermediate oxidation state (Sx, Na2S2O3, Na2SO3) and by adding silicate materials (e.g. quartz, rhyolite) as solids to the cell. The results of our studies will be useful for modeling of magma degassing and formation of magmatic ore deposits.

自然界中岩浆脱气过程中会产生大量含硫气体或流体，但在工业玻璃生产中熔体澄清过程中也会释放出含硫气体或流体，因为高温流体通常不可淬火，因此该项目的核心问题是研究此类气体或流体。使用拉曼光谱作为分析工具在高温和高压下原位流体，为此，我们开发了一种基于蓝宝石的新型单元，它允许在恒定温度下突然或连续变化压力，并在压力升高的情况下运行。高达 200 MPa 的温度和高达 800°C 的温度氧逸度 (fO2) 是决定流体中硫物质稳定性的关键参数。为了进行比较，将使用水热金刚石砧池技术来研究流体。在较高压力和密度下的等容条件下，这些实验还旨在确定与本研究相关的相对拉曼散射截面，并测试文献数据的适用性。为了便于解释拉曼光谱，我们希望从仅包含一种硫成分（例如 H2SO4、H2S、MgSO4、Na2SO4、计划通过使用不同硫源或中间氧化态源（Sx、Na2S2O3、Na2SO3）的组合以及添加硅酸盐材料（例如石英、流纹岩）作为固体来处理更复杂的岩浆流体。研究将有助于模拟岩浆脱气和岩浆矿床的形成。