Geochemistry of Siderophile and Chalcophile Element in the Earth: Studies on the Distribution of These Elements in Natural and Synthetic Samples

地球分化为金属地核、岩石硅酸盐壳层和液体/气体包层的过程，人们知之甚少。同位素研究表明，这一过程始于行星吸积期间，并在几千万年内结束。在地核和周围的硅酸盐地幔和地壳之间的元素分布可能发生在一系列条件下（温度、压力和气体逸度）和各种环境下，包括吸积到地球上的小型行星体。这些条件的综合结果记录在岩心与硅酸盐土之间的元素电流分布中。通过表征这两个储层的组成，并通过实验确定元素如何在金属和硅酸盐之间进行分配，我们可以了解岩心形成的机制。这项为期三年的研究的结果将包括分析地幔样品（橄榄岩和原长岩）中的亲铁（亲铁）和亲铜（亲硫）元素、地幔衍生岩浆（原始玄武岩、科马地岩及其某些矿物相）、陨石（特别是pallasites）；在特定压力、温度和氧化还原条件下合成的小行星样品（由铁金属混合橄榄石晶体组成）和实验电荷。橄榄岩、辉石岩和岩浆的数据将用于确定硅酸盐土的组成，这是其分化为地壳和地幔系统之前的原始地幔成分。陨石的研究将有助于建立元素在各种氧化还原条件下的低压和低温分馏行为。实验研究的数据将提供矿物和熔体之间元素的分布系数，这将进一步约束岩心形成的条件。所有这些研究都将对学生指导产生更广泛的影响，并为本科生和研究生提供研究机会。这些分析方法在科学、工业、医学和政府中都有应用，并将为这些学生的职业生涯提供很好的服务。

The process by which the Earth differentiated into a metallic core, a rocky silicate shell, and a liquid/gas envelope is poorly understood. Isotopic studies show that this process began during planetary accretion and ended within a few tens of millions of years. The distribution of elements between the core and surrounding silicate mantle and crust likely occurred under a range of conditions (temperature, pressure, and gas fugacity) and in a variety of settings, including small planetary bodies accreted into the Earth. The integrated result of these conditions is recorded in the current distribution of elements between the core and silicate Earth. By characterizing the composition of these two reservoirs and determining how elements partition themselves between metals and silicates with experiments, we can understand the mechanisms by which the core formed.The results of this three-year study will include analyses of the siderophile (iron-loving) and chalcophile (sulfur-loving) elements in mantle samples (peridotites and pryoxenites), mantle-derived magmas (primitive basalts, komatiites and some of their mineral phases), meteorites (particularly pallasites: asteroidal samples from their core-mantle boundary that are composed of iron metal mixed with olivine crystals) and experimental charges that have been synthesized under specific pressure, temperature and redox conditions. Data for the peridotites, pyroxenites and the magmas will be used to establish the composition of the silicate Earth, which is the primitive mantle composition prior to its differentiation into a crust and mantle system. The meteorite studies will help to establish the fractionation behavior of elements at low pressures and temperatures under various redox conditions. Data from the experimental studies will provide distribution coefficients for elements between minerals and melts, which will further constrain the conditions of core formation. All of these studies will have a broader impact on student mentoring, as well as providing research opportunities for undergraduate and graduate students. The analytical methods have applications in science, industry, medicine, and government and will serve these students well into their careers.