Earth's accretion history for volatile elements, and the origin of their depletions with respect to the Sun and primitive meteorites, continue to be debated. Two end-member scenarios propose either that volatile elements were delivered during the main phases of accretion and differentiation, or that the Earth accreted from materials largely devoid of volatiles with late addition of volatile-rich materials. Experiments evaluating the effect of metal–silicate equilibrium on elemental and isotopic distribution of volatile and siderophile elements such as Sn can help to distinguish between these scenarios. In this study, we have systematically investigated the relative influence of temperature, pressure, oxygen fugacity, and metal and silicate composition on the metal–silicate partioning behavior of Sn, from 2 to 20 GPa and 1,700 to 2,573 K, indicating that Sn siderophility noticeably decreases with temperature and S content of the metal but increases dramatically with pressure. A resolvable isotopic fractionation factor between metal and silicate suggests that core–mantle equilibrium temperatures (∼3,000 K) could potentially generate a Sn isotopic composition of the mantle lighter than the core by 150–200 ppm/amu. Core formation modeling shows that the volatiles were added during the last 10% of the accretion history. A final core containing 2.5 to 3.5 wt.% S is required. Furthermore, modeling of the BSE isotopic composition argues for a late Sn delivery on Earth with carbonaceous chondrite-like material as the most likely source of volatiles. Therefore, both elemental and isotopic approaches converge toward an identical volatile accretion scenario, involving a late volatile delivery.

中文翻译：

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用锡追踪地球的挥发性物质

地球上挥发性元素的吸积历史，以及它们相对于太阳和原始陨石的损耗的起源，仍在争论中。两种最终成员情景提出，要么在吸积和分化的主要阶段释放挥发性元素，要么地球从基本上不含挥发性物质的材料中吸积而后添加富含挥发性物质的物质。评估金属-硅酸盐平衡对挥发性和亲铁元素（如 Sn）的元素和同位素分布影响的实验有助于区分这些情况。在这项研究中，我们系统地研究了温度、压力、氧逸度以及金属和硅酸盐成分对 Sn 的金属-硅酸盐分配行为的相对影响，从 2 到 20 GPa 和 1,700 到 2,573 K，表明 Sn 的亲铁性随温度和金属的 S 含量显着降低，但随压力显着增加。金属和硅酸盐之间可解析的同位素分馏因子表明，地核-地幔平衡温度（~3,000 K）可能会产生比地核轻 150-200 ppm/amu 的地幔的 Sn 同位素组成。岩心形成模型显示，在吸积历史的最后 10% 期间添加了挥发物。需要含有 2.5 至 3.5 wt.% S 的最终核心。此外，BSE 同位素组成的建模表明，地球上的 Sn 传输较晚，碳质球粒陨石样材料是最有可能的挥发物来源。因此，元素方法和同位素方法都趋向于相同的挥发性吸积情景，