The role of p-T conditions, host rock lithology, phase separation, and organic compounds on metal mobility and metal sulfide deposition in spatially resolved hydrothermal vent areas

热液流体和相关矿物沉淀物的化学成分取决于不同的参数和过程，包括寄主岩石成分、压力和温度（p，T）条件、地下流体通道、水-岩比、相分离和相分离以及岩浆脱气。此外，已知溶解的有机分子（微生物产生的或水热降解的有机材料的产物）具有部分强的金属络合能力，其可以显著影响金属传输和溶解度相对于沉淀。因此，独特的热液成分的签名产生的这些参数和时间。虽然已确定了迄今发现的许多喷口区的端元组成，但往往难以明确确定个别过程对流体和从中沉淀的矿物的总体化学组成的作用。我们建议进行实地调查，并阐明个别参数的作用，包括主机岩石类型，温度，相分离，和有机质实验。我们将探讨利用喷口流体和沉淀物的Sr、Li和B同位素特征作为受特定参数控制的流体示踪剂的可能性。这将有助于我们理清这些因素在自然喷口环境中的各自作用，并预测热液流体中的金属富集和矿化作用随环境参数的变化。对于实地工作，我们将重点关注缓慢扩展的山脊系统，这些系统已被证明是热液系统的宿主，在较长的时间内（至少几十年），热液系统的活动和成分是稳定的。这使我们能够排除作为附加变量的时间因素。我们将利用我们参与即将进行的中大西洋中脊北方巡航的机会，以及与BGR汉诺威的合作，以及他们定期对印度中脊和东南脊的德国许可区进行研究巡航，作为INDEX项目的一部分。在实验工作中，将在高达400°C的温度下使用装有样品（液体和固体）的柔性金袋的高压灭菌器;在这里，将测试各个参数在金属动员和沉淀方面的效率以及相关的同位素特征。最后，使用地球化学家GWB的热力学建模，计算在特定条件下的固溶平衡和反应路径将被应用，使用我们的现场和实验数据作为基线和验证。我们预计，该项目的成果将使我们能够更好地了解热液成矿和现代技术感兴趣的特殊金属富集的控制因素，并指导此类矿床的勘探。

The chemical composition of hydrothermal fluids and related mineral precipitates depend on different parameters and processes, which include host rock composition, pressure and temperature (p, T) conditions, fluid pathways in the subsurface, water-to-rock ratio, phase separation and phase segregation, and magmatic degassing. In addition, dissolved organic molecules (either microbially produced or products of hydrothermally degraded organic material) are known to have partly strong metal complexing capacities that can significantly influence metal transport and solubility versus precipitation. Hence, distinctive hydrothermal compositional signatures are produced in relation to these parameters, and time. While end-member compositions have been determined for many vent fields discovered so far, it has often been difficult to clearly identify the role of individual processes on the overall chemical composition of the fluids and minerals precipitating from them. We suggest carrying out both field investigations and to elucidate the role of individual parameters, including host rock type, temperature, phase separation, and organic matter experimentally. We will explore the possibility of using Sr, Li and B isotope signatures of vent fluids and precipitates as tracers of fluids controlled by specific parameters. This will help us to disentangle the respective roles of these factors in natural vent settings and predict metal enrichment in hydrothermal fluids and mineralization as a function of the environmental parameters. For the field work, we will focus on slow-spreading ridge systems, which have been shown to host hydrothermal systems that are stable in activity and composition over longer periods (at least decades) of time. This enables us to exclude the factor time as an additional variable. We will use the opportunity of our participation in upcoming cruises to the northern Mid-Atlantic Ridge and the collaboration with the BGR Hannover and their regular research cruises to the German license areas on the Central and Southeast Indian Ridge as part of the INDEX project. For the experimental work, autoclaves with flexible gold bags containing the samples (liquid and solids) will be used at temperatures up to 400°C; here, the individual parameters will be tested for their efficiency in metal mobilization and precipitation and the related isotopic signatures. Finally, thermodynamic modeling using Geochemists Workbench GWB, for calculating solid-solution equilibria under specific conditions and reaction paths will be applied, using our field and experimental data as baselines and for verification. We anticipate that the results of this project will enable us to better understand the control factors of hydrothermal ore formation and enrichment of special metals of interest for modern technologies and to guide exploration of such deposits.