Neodymium in Silicate Melts and Glasses at High Pressure: How Bonding Environment Changes with Pressure

Abstract:

A basic understanding of how trace elements are incorporated in silicate melts is critical to assess our understanding of trace element partitioning during the early stages of planetary formation and large scale magmatic processes. Although it is well known that melt compositional changes affect the partitioning of trace elements, the degree to which these ratios are influenced by pressure-induced modifications in melt structure is poorly constrained due to the difficulty of collecting structural information on bonding environments in-situ.

Here we present results from in-situ diamond anvil cell (DAC) X-ray diffraction experiments on the local environment of neodymium in depolymerised (basaltic) silicate melts at pressures up to 60 GPa. High temperature conditions were generated through laser heating DACs and high quality structural data was collected up to >6 Å. We explore the effect of pressure on trace element speciation in both melt and glass phases. Our in-situ data on the bonding environment provides much needed insight into the influence of melt structure on trace element behaviour, and will allow more realistic models of trace elements partitioning within the mantle.