Halogens in the Earth's mantle: Concentrations in nominally halogen-free mantle minerals and element partitioning during partial melting

一段时间以来，人们都知道，名义上不含水的矿物可以在地幔中储存大量的水。这从根本上提高了我们对地球内部的理解，因为即使是少量的水也会对地幔的相稳定性、熔融关系和流变性产生实质性的影响。拟议的项目现在旨在首次调查各种地幔矿物中氟(F)和氯（Cl）的元素浓度。这可能很重要，因为预计F和Cl在地幔中具有与水相似的作用，特别是在部分熔融和流变特性方面。名义上无卤素的地幔矿物中的F和Cl浓度非常低，将用专门设计的原位方法进行测量，称为二次离子质谱（SIMS）。为了更好地理解地幔岩石和衍生玄武岩中F和Cl的地球化学行为，我们还将确定地幔矿物和玄武岩熔体之间F和Cl的分配。这些分配系数将有助于了解卤素在地幔部分熔融和玄武岩分馏过程中的行为。

It has been well known for some time that nominally water-free minerals can store significant amount of water in Earth's mantle. This has fundamentally improved our understanding of Earth's interior as even small amounts of water are known to substantially affect phase stability, melting relations, and rheology of the mantle. The proposed project now aims to investigate, for the first time, element concentrations of Fluorine (F) and Chlorine (Cl) in a variety of mantle minerals. This could be important, as F and Cl are expected to have similar effects as water in the mantle, especially in regards to partial melting and rheological properties. F and Cl concentrations in nominally halogen-free mantle minerals are very low and will be measured with specifically designed in-situ methods, called secondary ion mass spectroscopy (SIMS). To better understand the geochemical behaviour of F and Cl in mantle rocks, and derived basalts, we will also determine the partitioning of F and Cl between mantle minerals and basaltic melts. These partition coefficients will help to understand how halogens behave during partial melting of the mantle and during fractionation of basalt.