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S地壳内的大型金属富集物。世界级矿床的形成需要从大量源岩中高效地提取金属，通过热液有效地输送金属，以及局部和有效地进行金属沉淀。流体-岩石相互作用是金属溶解、运移和矿石矿物沉淀过程中必不可少的过程。矿床形成和热液蚀变流体过程的地球化学热力学模拟是发展新一代矿产勘查模式的有力工具。稳健的热力学数据是准确模拟金属和矿物溶解度以及流体-岩石反应的基本前提。这项提议寻求资金，以开发一个新的内部一致的铜和铁在热液系统中运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。这项拟议的研究建立在先前工作的基础上，这些工作以矿石地质、蚀变岩石地球化学、稳定同位素和流体包裹体研究为基础，论述了南澳大利亚世界级突出山IOGC矿床的关键热液过程。该项目分为四个工作包，将共同有助于从根本上了解S地壳中热液铜矿的形成方式。在A工作包中，将开发一种新的热力学数据回归模块GEMSSPEC，它可以同时处理实验矿物溶解度和光学光谱数据。工作包B将根据苏黎世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体系的流体-矿物平衡生成内部一致的热力学数据集。精心挑选的铜和铁矿物溶解度实验数据和光谱数据将用于水相物种的标准吉布斯能量的全球拟合，以得出铜和铁在热液流体中迁移的一致模型。在工作包C中，新的热力学数据集将应用于世界级突出的Hill IOCG矿床，该矿床的岩石成分、蚀变矿物学和成矿流体化学的数据集已经建立。使用GEMS3程序进行的地球化学热力学模拟将得到突出山矿床的定量过程模型，该模型可用于了解世界各地的IOCG系统。在工作包D中，新的热力学模型将用于研究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.