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

• Applicant: Dr. Maria Kirchenbaur
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: from 2013 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 234825916

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.

• DFG Programme: Research Grants
• International Connection: Australia
• Participating Persons: Professor Dr. Harry Becker; Dr. Carl-Dieter Garbe-Schönberg; Professor Dr. Vadim Kamenetsky