The hydrogeological regime of the TAG sulfide mound on the Mid-Atlantic Ridge - Insights into metal fluxes from reaction-transport modeling

海底块状硫化物（SMS）是古火山成因块状硫化物（VMS）的现代类似物，可能代表未来的金属资源。它们的形成是对年轻海底热液冷却的反应，当时从岩浆热源上升的热流体与海水混合，使其金属负载存款。大西洋中脊的TAG热液丘是最大的海底硫化物堆积区之一，是研究控制过程的绝佳地点。它的内部结构已经通过海洋钻探（ODP 158）进行了探测，并获得了广泛的地质和地球物理数据。然而，详细的水文地质制度和化学沉淀和溶解过程，使土堆从来没有量化的反应-传输模型和主要的知识差距仍然存在-其结果是，可能的全球SMS禀赋和热液喷口在全球地球化学循环的作用仍然受到很大的限制。在这里，我们将使用3-D反应传输模型来缩小这些知识差距。我们的方法是耦合现有的3-D热液流模型，hydrothermalFoam，与热力学MINES数据库的流体岩石相互作用，使用GEMS 3 K软件吉布斯自由能最小化。这将使我们能够测试TAG热液丘的形成方案，并阐明控制热液金属通量进入，内部和出热液土丘的主导过程。

Submarine massive sulfides (SMS) are the modern analogues of ancient volcanogenic massive sulfides (VMS) and may represent a future metal resource. They form in response to hydrothermal cooling of the young ocean floor, when hot fluids rising from a magmatic heat source mix with seawater to deposit their metal load. The TAG hydrothermal mound on the Mid-Atlantic Ridge hosts one of the largest submarine sulfide accumulations and is an excellent location for studying the controlling processes. Its internal structure has been probed by ocean drilling (ODP 158) and extensive geological and geophysical data is available. Yet, the detailed hydrogeological regime and the chemical precipitation and dissolution processes that made the mound have never been quantified with reaction-transport models and major knowledge gaps remain – with the consequence that the likely global SMS endowment and also the role of hydrothermal venting in global biogeochemical cycles remain poorly constrained. Here, we will work on narrowing these knowledge gaps using 3-D reaction-transport modeling. Our approach is to couple an existing 3-D hydrothermal flow model, hydrothermalFoam, with the thermodynamic MINES database for fluid rock interactions using the GEMS3K software for Gibbs Free Energy minimization. This will allow us to test scenarios for the formation of the TAG hydrothermal mound and to elucidate the dominant processes that control hydrothermal metal fluxes into, within, and out of hydrothermal mounds.