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    Diamond anvil cell partitioning experiments for accretion and core formation: testing the limitations of electron microprobe analysis

    Jennings, Eleanor S. and Wade, J. and Laurenz, V. and Petitgirard, S. (2019) Diamond anvil cell partitioning experiments for accretion and core formation: testing the limitations of electron microprobe analysis. Microscopy and Microanalysis 25 (1), pp. 1-10. ISSN 1431-9276.

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    Abstract

    Metal-silicate partitioning studies performed in high pressure, laser-heated diamond anvil cells (DAC) are commonly used to explore element distribution during planetary-scale core-mantle differentiation. The small run-products contain suitable areas for analysis commonly less than tens of microns in diameter and a few microns thick. Because high spatial resolution is required, quantitative chemical analyses of the quenched phases is usually performed by electron probe microanalysis (EPMA). Here, EPMA is being used at its spatial limits, and sample thickness and secondary fluorescence effects must be accounted for. By using simulations and synthetic samples, we assess the validity of these measurements, and find that in most studies DAC sample wafers are sufficiently thick to be characterised at 15 kVacc. Fluorescence from metal-hosted elements will, however, contaminate silicate measurements, and this becomes problematic if the concentration contrast between the two phases is in excess of 100. Element partitioning experiments are potentially compromised; we recommend simulating fluorescence and applying a data correction, if required, to such DAC studies. Other spurious analyses may originate from sources external to the sample, as exemplified by 0.5 to > 1 wt.% of Cu arising from continuum fluorescence of the Cu TEM grid the sample is typically mounted on.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): EPMA, diamond anvil cell, partitioning, PENEPMA, planetary accretion, core formation
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Research Centre: Earth and Planetary Sciences, Institute of
    Depositing User: Eleanor Jennings
    Date Deposited: 05 Nov 2018 09:21
    Last Modified: 27 Jul 2019 07:01
    URI: http://eprints.bbk.ac.uk/id/eprint/24938

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