Reactive Transport Modelling of Ore Formation in Sedimentary Basins

沉积物矿床是Zn、Pb、Cu等贱金属和许多其他重要金属（如In、Ge、Ga）的主要资源，这些金属对于向碳中和社会过渡具有战略重要性。盆地尺度热液系统中金属矿的富集是不同时空尺度上化学和物理过程完美汇聚的结果，只有通过存款尺度以外的观测和研究才能定量地了解这些系统。数值过程模型有可能确定对成矿的一级控制，并对热液系统生成世界级矿床的可行性和效率提供物理和化学限制，这可能有助于指导未来的勘探。近年来，建模方面的主要进展要么集中在地球化学-地球化学流体-岩石相互作用方面，要么集中在物理水文学方面，而热液系统的全面反应输运建模仅限于简化系统。在拟议的项目中，我们将使用地球化学模型GEMS 3和流体流动模型CSMP++，开发和应用沉积盆地成矿反应输运模型。由此产生的完全耦合的数值模型将能够：1）捕捉与金属流动、迁移和沉淀有关的化学和物理过程之间的相互作用; 2）将金属富集所需的时间和空间尺度限制在经济级别。利用该模型，我们将定量研究关键参数如流体盐度、氧化态、pH值、金属和硫的有效性、盆地尺度热通量、地形、盆地地层、孔隙空间和渗透流体通道对矿石金属富集动力学的各自作用。该项目将从简单的通用设置开始开始，然后逐渐增加地质复杂性。地球化学模型GEMS 3可以包含由全球回归方法提供的主要成岩和成矿元素的内部一致的数据库。流体流动模型CSMP++可以将地球动力学模型提供的热通量、岩石单元和断层的地质现实约束结合起来。我们将主要解决一级过程形成沉积物托管的铅锌矿床，但该模型将提供更广泛的应用到其他热液系统的潜力。该项目将有助于优先方案DOME的总体目标，通过跨学科方法解决成矿的关键机制，我们将推进使用实验和分析数据确定的流体和岩石特性的数值方法，旨在解释铅锌矿床的主要特征。这一合作项目是由DOME方案第一阶段的两个模拟项目合并而成的，将具有与处理沉积物矿床和其他低温矿床的项目进一步合作的巨大潜力。

Sediment-hosted ore deposits are major resources for base metals like Zn, Pb, Cu and many other mass and critical metals (e.g. In, Ge, Ga) that are of strategic importance for the transition towards a carbon-neutral society. Ore metal enrichment in basin-scale hydrothermal systems results from a perfect convergence of chemical and physical processes on different temporal and spatial scales, and these systems can only be quantitatively understood by observations and studies beyond the deposit scale. Numerical process models have the potential to identify first-order controls on ore formation and provide physical and chemical constraints on the feasibility and efficiency of hydrothermal systems to generate world-class deposits, which may help guiding future exploration. Major advances in modelling in recent years have either focused on thermodynamic-geochemical fluid-rock interaction or on physical hydrology, while full reactive transport modelling of hydrothermal systems was limited to simplified systems. In the proposed project, we will develop and apply a reactive transport model for ore formation in sedimentary basins, using the geochemical model GEMS3 and the fluid flow model CSMP++. The resulting fully coupled numerical model will be able to 1) capture the interplay between the chemical and physical processes relevant for metal mobilization, transport and precipitation, and 2) constrain the temporal and spatial scales required for metal enrichment to economic grades. With this model, we will quantitatively investigate the respective roles of key parameters like fluid salinity, oxidation state, pH, metal and sulfur availability, basin-scale heat flux, topography, basin strata, pore space and permeable fluid pathways on the dynamics of ore metals enrichment. The project will begin with simple generic settings and then successively increase the geological complexity. The geochemical model GEMS3 can incorporate internally consistent databases for the main rock-forming and ore elements provided by a global-regression approach. The fluid flow model CSMP++ can incorporate geologically realistic constraints on heat flux, rock units and faults provided by a geodynamic model. We will mainly address first-order processes forming sediment-hosted Pb-Zn deposits, but the model will provide much wider potential for applications to other hydrothermal systems. The project will contribute to the overarching goal of the priority programme DOME by addressing key mechanisms of ore formation in a trans-disciplinary approach, where we advance numerical methods that use fluid and rock properties determined by experimental and analytical data and aim at explaining the key features of Pb-Zn deposits. The collaborative project has evolved from the combination of two modelling projects of the first phase of the DOME programme and will have great potential for further collaborations with projects addressing sediment-hosted and other low-temperature ore deposits.