Internally-consistent thermodynamic model for hydrothermal transport of Pb-Zn-Ag-Au-As-Sb: development and application to formation of sediment-hosted Pb-Zn and epithermal Ag-Au-As-Sb deposits

热液矿床是地壳中的大型金属富集物，世界级矿床的形成需要从大量烃源岩中高效提取金属，通过热液流体高效运输，以及局部有效的金属沉淀。岩浆-热液斑岩型Cu-Au - Mo和浅成热液型Ag-Au-As-Sb矿床以及沉积型铅锌矿床是形成世界级矿床的重要过程。对驱动矿床形成和热液蚀变的流体过程进行地球化学-热力学建模是开发下一代矿系模型的有力手段。稳健的热力学数据集是准确模拟金属和矿物溶解度和流体-矿物反应的必要先决条件。本提案寻求资金用于开发一种新的内部一致的Pb-Zn-Ag-Au-As-Sb热液输送地球化学-热力学模型，从而显著扩展我们现有的数据集。该数据集将用于数值模拟控制沉积型和碳酸盐型铅锌矿床以及浅成热液型银、金、砷、锑矿床形成的一级地球化学过程。该模型将解决与这些全球重要矿床类型形成相关的关键问题，即还原酸和氧化盐水在沉积型铅锌系统中的相对作用，喷出型和碳酸盐型铅锌矿床之间的联系，以及类金属As和Sb对Cu、Pb、Zn、Ag和Au热液运输的影响。该项目分为三个工作包，它们将共同对热液沉积物中铅锌和岩浆热液中银、金、砷、锑矿床如何在地壳中形成有基本的了解。在工作包A中，基于我们最近开发的新的数据回归方法，将建立一个新的内部一致的Pb-Zn-Ag-Au-As-Sb热液输运热力学模型。严格评估Pb-Zn-Ag-Au-As-Sb的实验溶解度和光谱数据将用于水相的标准吉布斯能的全球拟合，以得出热液金属运输的一致热力学模型。在工作包B和C中，使用GEMS3软件的地球化学建模将解决控制沉积型铅锌矿床和侵入体相关浅成热液型Ag-Au-As-Sb矿床形成的一级过程。该项目将通过与解决超低温系统形成的对应项目合作，通过生成可供其他DOME参与者使用的热力学数据集，以及通过生成可通过其他DOME项目的实地研究进行测试的建模预测，为DOME优先计划的总体目标做出重要贡献。

Hydrothermal ore deposits are large metal enrichments in the Earthʼs crust and the formation of world-class 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-mineral interactions are essential processes that lead to formation of world-class ore deposits such as magmatic-hydrothermal porphyry Cu-Au Mo and epithermal Ag-Au-As-Sb deposits, and sediment-hosted Pb-Zn deposits. Geochemical-thermodynamic modeling of the fluid processes driving ore deposit formation and hydrothermal alteration is a powerful approach for developing next generation ore systems models. Robust thermodynamic datasets are an essential prerequisite to accurately simulate metal and mineral solubilities and fluid-mineral reactions. This proposal seeks funding for developing a new internally-consistent geochemical-thermodynamic model for hydrothermal transport of Pb-Zn-Ag-Au-As-Sb, thereby significantly extending our existing dataset. The dataset will be applied to numerically simulate the first-order geochemical processes that control formation of sediment-hosted exhalative and carbonate hosted Pb-Zn deposits and of epithermal Ag Au-As-Sb deposits. The modeling will address key questions related to formation of these globally important ore deposit types, namely the relative role of reduced acid and oxidized brines in sediment-hosted Pb-Zn systems, the link between exhalative and carbonate hosted Pb-Zn deposits, and the effect of the metalloids As and Sb on the hydrothermal transport of Cu, Pb, Zn, Ag and Au. The project is organized as three work packages that will jointly lead to fundamental understanding of how hydrothermal sediment-hosted Pb Zn and magmatic-hydrothermal Ag-Au-As-Sb deposits form in the Earthʼs crust. In work package A, a new internally-consistent thermodynamic model for hydrothermal transport of Pb-Zn-Ag-Au-As-Sb will be developed, based on our new data regression approach that was recently developed. Critically evaluated experimental solubility and spectroscopic data for Pb-Zn-Ag-Au-As-Sb will be used for global fitting of the standard Gibbs energies of aqueous species to derive a consistent thermodynamic model for hydrothermal metal transport. In work packages B and C, geochemical modeling using the GEMS3 software will address the first-order processes that control formation of sediment-hosted Pb-Zn deposits and intrusion-related epithermal Ag-Au-As-Sb deposits. This project will make important contributions to the overaching goals of the DOME priority program, by collaboration with a counterpart project addressing the formation of epithermal systems, by producing a thermodynamic dataset ready for use by other DOME participants, and by generating modeling predictions that can be tested by field-based studies of other DOME projects.