The geochemical behaviour of Sn and In during mantle melting and crust formation

铟和锡是中等至高度挥发性和中等亲铁/亲铜元素组的一部分。在行星吸积过程中，这些元素被认为是在核心形成时被部分清除到核心中，并通过后期单板额外输送到早期地球。例如，铟是极少数元素之一，在陆地地幔中比预期的更丰富，从丰富的类似挥发性亲石元素，而锡似乎略有亏损。然而，缺乏高质量的数据，这些元素的分布在主要的陆地硅酸盐水库，以及缺乏系统的研究如何锡和在地质过程中的行为（如地幔熔融和地壳形成），目前阻碍了足够准确的估计地幔丰度。传统上，这样的估计是基于Sn/Sm和In/Y元素对，长期以来被认为是未分馏的火成岩过程中。然而，最近的锡-铟火成岩数据似乎表明，这些元素的比例是高度分馏在某些重要的情况下，特别是在俯冲带。该项目旨在获得关于特征良好和精心挑选的橄榄岩和原始玄武岩的高精度In-Sn数据，以便对以下方面提供重要见解：（1）In和Sn在地球硅酸盐储层和原始地幔中的分布，（2）它们在地球主要分异事件期间的行为，并评估In和Sn作为此类事件示踪剂的潜力，例如，（3）Sn、In的富集/贫化过程及其与Sm、Y等不相容微量元素的分馏作用。

Indium and tin are part of the moderately to highly volatile and moderately siderophile/chalcophile element group. During planetary accretion, these elements are thought to have been partially scavenged into the core as it formed and additionally delivered to the Early Earth by the Late Veneer. Indium, for example, is one of the very few elements that are more abundant in the terrestrial mantle than expected from the abundance of similarly volatile lithophile elements whereas Sn appears to be slightly depleted. However, the scarcity of high-quality data on the distribution of these elements in major terrestrial silicate reservoirs as well as the lack of systematic studies on how Sn and In behave during geological processes (e.g. mantle melting and crust formation), currently hamper sufficiently accurate estimates on the mantle abundances. Traditionally, such estimates were based on the Sn/Sm and In/Y element pairs that were long considered to be unfractionated during igneous processes. More recent Sn-In data for igneous rocks, however, appear to indicate that these element ratios are highly fractionated in some important cases, and especially in subduction zones. This project aims to obtain high-precision In-Sn data on well-characterized and carefully selected peridotites and primitive basalts in order to give important insights into (1) the distribution of In and Sn in the Earth's silicate reservoirs and the primitive mantle, (2) their behaviour during the major differentiation events of the Earth and assess the potential of In and Sn as tracers for such events, e.g., the Late Veneer, and (3) the processes that control the enrichment/depletion of Sn and In and their fractionation from similarly incompatible trace elements like Sm and Y.