In situ deciphering of Zr structure in mafic-ultramafic melts: Implications for the mantle-derived kimberlite magmatism

The goal of this research project is to understand the origin and survival of zircon in the presence of mantle melts at lithosphere – asthenosphere boundary. Because most magmatic systems are unquenchable, meaning a strong effect of quenching on the structure of melt upon transition to glass, the Zr speciation should be investigated in-situ. In-situ experiments will be conducted with silicate-carbonate mafic-ultramafic melts doped with ZrO2 (at 1 to 5 wt% level). EXAFS, a part of the X-ray absorption spectrum, will be used to investigate Zr speciation providing detailed information on the coordination number and environment of Zr atoms. These in-situ measurements at high pressure and temperature require large-volume techniques such as Paris Edinburgh Press (PEP). It is available on BM23 and ID24-DCM. We will examine Zr speciation using four compositions for the pressure range 2 – 10 GPa. This would require 18 shifts in total considering 3 shifts for beamline alignment investigation.