Hydrothermal transport of Cu and Fe: internally-consistent thermodynamic model and application to formation of world-class iron-oxide-copper-gold (IOCG) ore deposits

热液矿床是地壳内的大型金属富集区。世界级矿床的形成需要从大量的源岩中高效提取金属、热液流体的高效迁移以及局部有效的金属沉淀。流体-岩石相互作用是金属溶解、迁移和矿物沉淀的重要过程。存款形成和热液蚀变过程的地球化学-热力学模拟是开发新一代矿产勘查模型的有力工具。强大的热力学数据集是准确模拟金属和矿物溶解度以及流体-岩石反应的必要前提。该提案寻求资金，用于开发一个新的内部一致的热液系统中铜和铁迁移的地球化学-热力学模型，并应用该数据集模拟控制世界级氧化铁铜金（IOCG）和铜带型页岩铜矿床矿化和蚀变的成矿过程。拟议的研究建立在早期工作的基础上，这些工作基于矿石地质学、蚀变岩石地球化学、稳定同位素和流体包裹体研究，解决了位于南澳的世界级Prominent Hill IOGC存款的关键热液过程。该项目由四个工作包组成，将共同促进对热液铜矿床如何在地壳中形成的基本理解。在工作包A中，将开发新的热力学数据回归模块GEMSSPEC，该模块可同时处理矿物溶解度实验数据和光学光谱数据。工作包B将根据苏黎世联邦理工学院最近开发的一种新的数据回归方法，为Na-K-Mg-Fe-Cu-Al-Si-C-S-Cl-O-H系统中的流体-矿物平衡生成一个内部一致的热力学数据集。精心挑选的实验铜和铁矿物的溶解度和光谱数据将用于全球拟合的标准吉布斯能的水相物种，以获得一个一致的模型，在热液流体中的铜和铁的运输。在工作包C中，新的热力学数据集将应用于世界级的Prominent Hill IOCG存款，其岩石成分、蚀变矿物学和矿石流体化学数据集已经建立。使用GEMS 3代码进行的地球化学-热力学建模将产生Prominent Hill存款的定量过程模型，该模型可用于了解全球IOCG系统。在工作包D中，新的热力学模型将用于解决铜带型页岩铜矿床的一级过程。

Hydrothermal ore deposits are large metal enrichments within the Earth´s crust. The formation of world-class ore deposits requires highly efficient extraction of metals from large volumes of source rocks, efficient transport by hydrothermal fluids and localized and effective metal precipitation. Fluid-rock interactions are essential processes during metal dissolution, transport and precipitation of ore minerals. Geochemical-thermodynamic modeling of fluid processes involved in ore deposit formation and hydrothermal alteration is a powerful tool for developing next-generation mineral exploration models. Robust thermodynamic datasets are an essential prerequisite to accurately simulate metal and mineral solubilities and fluid-rock reactions. This proposal seeks funding for developing a new internally-consistent geochemical-thermodynamic model for Cu and Fe transport in hydrothermal systems and applying this dataset to model the ore-forming processes that control mineralization and alteration in world-class iron-oxide-copper-gold (IOCG) and Copperbelt-type shale-hosted copper ore deposits. The proposed research builds on earlier work that addressed the key hydrothermal processes of the world-class Prominent Hill IOGC deposit in South Australia, based on ore geology, alteration lithogeochemistry, stable isotope and fluid inclusion studies. The project is organized as four work packages that will jointly contribute to fundamental understanding of how hydrothermal Cu ore deposits form in the Earth´s crust. In work package A, the new thermodynamic data regression module GEMSSPEC that can simultaneously treat experimental mineral solubility and optical spectroscopic data will be developed. Work package B will generate an internally consistent thermodynamic dataset for fluid-mineral equilibria in the system Na-K-Mg-Fe-Cu-Al-Si-C-S-Cl-O-H based on a new data regression approach recently developed at ETH Zürich. Carefully selected experimental Cu and Fe mineral solubility and spectroscopic data will be used for global fitting of the standard Gibbs energy of aqueous species to derive a consistent model for Cu and Fe transport in hydrothermal fluids. In work package C, the new thermodynamic dataset will be applied to the world-class Prominent Hill IOCG deposit for which datasets for rock composition, alteration mineralogy and the chemistry of ore fluids have been established. Geochemical-thermodynamic modeling using the GEMS3 code will result in a quantitative process model for the Prominent Hill deposit, which can be used to understand IOCG systems worldwide. In work package D, the new thermodynamic model will be used to address the first-order processes of Copperbelt-type shale-hosted Cu ore deposits.