Chemical and physical properties of magmatic sulfides and sulfide liquids at conditions of Earth’s deep upper mantle

贱金属硫化物（Fe-Ni-Cu-S +/- Co和Zn）和硫化物熔体是玄武岩、橄榄岩和地幔捕虏体中普遍存在的附属相，也是金刚石中最常见的包裹体。由于它们的性质，它们是高亲铁元素（HSE）和经济上重要的亲铜元素（如铂族元素、Cu、Zn、Ag和Pb）的汇。行星物质中HSE的丰度通常用于跟踪行星储层和岩心形成的演化，并结合Re-Os放射性衰变系统的信息，为我们提供了对行星尺度过程年代学的见解。Fe-Ni-Cu-S包裹体在钻石中含量过高，这表明硫化物和钻石之间存在遗传联系。我们计划更密切地研究从岩石圈和岩石圈下钻石中回收的类似天然包裹体的成分，即具有明显的榴辉岩和橄榄岩金属与S和铁与镍比的成分。为了补充在浅层地幔条件下进行的现有实验数据，我们将在深部地幔条件下（即低于上地幔底部200 km深度）进行高压/高温实验，并与不同的硅酸盐/氧化物（橄榄石，wadsleyite, ringwoodite， majorite和stishovite）进行平衡，以揭示硫化物饱和的条件及其对硫化物，硫化物熔体和硅酸盐之间元素分配的影响。与硅酸盐和硅酸盐熔体相比，硫化物熔体具有明显不同的物理性质（例如密度、粘度、电导率）。如果硫化物熔体形成一个相互连接的网络，这取决于硫化物熔体与共存的硅酸盐之间的固体-固体和固体-熔体界面能，以及氧和硫的逸出率，它们将显著促进亲铁和亲铜元素的运输，以及在行星核心形成过程中有效金属分离的可能性。此外，硫化物熔体可以溶解大量的碳，在大型钻石的形成中起着关键作用。我们将确定硫化物熔体与高压地幔相共存的二面角，以确定硫化物熔体在深部地幔活动的条件。此外，我们将讨论C的溶解度以及在代表地球过渡带的压力下硫化物熔体中钻石的沉淀。

Base metal sulfides (Fe-Ni-Cu-S +/- Co, and Zn) and sulfide melts are ubiquitous accessory phases in basalts, peridotites, and mantle xenoliths, and are the most frequent inclusions in diamonds. Due to their nature, they are a sink for highly siderophile elements (HSE) and economically important chalcophile elements like platin-group elements, Cu, Zn, Ag, and Pb. The abundances of HSE in planetary materials are commonly used to track the evolution of planetary reservoirs and core formation, which in conjunction with information of the Re-Os radioactive decay systems, provides us with insights into the chronology of planetary-scale processes. Fe-Ni-Cu-S inclusions are overabundant in diamonds and suggests that a genetic link between sulfides and diamonds exists. We plan to investigate compositions that resemble natural inclusions recovered from lithospheric and sublithospheric diamonds more closely, i.e. compositions with a distinct eclogitic and peridotitic metal to S and Fe to Ni ratio. To complement existing experimental data, carried out at shallow mantle conditions, we will conduct high-pressure/high-temperature experiments at deep mantle conditions (i.e. below 200 km depths to the base of the upper mantle) in equilibrium with different silicates/oxides (olivine, wadsleyite, ringwoodite, majorite, and stishovite) to unravel the conditions of sulfide saturation and their effect on element partitioning between sulfides, sulfide melts, and silicates.Sulfide melts have distinctly different physical properties (e.g. density, viscosity, electrical conductivity) compared to silicates and silicate melts. If sulfide melts develop an interconnected network, which depends on the solid-solid and solid-melt interfacial energies between sulfide melts and coexisting silicates, as well as oxygen and sulfur fugacity, they will significantly contribute to the transport of siderophile and chalcophile elements, as well as the likelihood of efficient metal segregation during planetary core formation. Moreover, sulfide melts can dissolve significant amounts of C and play a key role in the genesis of large diamonds. We will determine the dihedral angle of sulfide melts coexisting with high-pressure mantle phases to identify the conditions under which sulfide melts are mobile in the deep mantle. Moreover, we will address the solubility of C and the precipitation of diamonds from sulfide melts at pressures that represent Earth’s transition zone.