University of Tasmania
Browse
CG-09-Cu-spec.pdf (529.56 kB)

The speciation of copper in natural fluid inclusions at temperatures up to 700 degrees C

Download (529.56 kB)
journal contribution
posted on 2023-05-17, 01:51 authored by Berry, AJ, Anthony HarrisAnthony Harris, Vadim Kamenetsky, Newville, M, Sutton, SR
Copper K-edge X-ray absorption spectra were recorded from natural polyphase brine fluid inclusions in miarolitic quartz from the Omsukchan Granite, Russia, as a function of temperature up to 700 degrees C. The inclusions studied represent two distinct fluids, which contain either 0.02 or 0.94 wt.% Cu homogeneously distributed in solution at temperatures above salt dissolution (350-550 degrees C). X-ray absorption near edge structure (XANES) spectra of the solution phase in the Cu-poor inclusions exhibit an intense edge feature near 8983 eV that is characteristic of the linear [CuCl2](-) complex. This spectrum was obtained at all temperatures between 200 and 700 degrees C and from around 15 inclusions. Extended X-ray absorption fine structure (EXAFS) spectra recorded at 550 degrees C were modelled to give a Cu-Cl bond length of 2.11(2) angstrom, also consistent with [CuCl2](-). XANES spectra of the Cu-rich inclusions appear similar to that of [CuCl2](-) but are shifted to higher energy. This spectrum was obtained between 350 and 700 degrees C and from all three inclusions studied. EXAFS recorded at 700 degrees C gave a Cu-ligand bond length of 2.19(1) angstrom. This complex is yet to be identified. The results for the Cu-poor inclusions indicate that [CuCl2](-) is stable at magmatic temperatures, extending the known range of this complex by 200 degrees C. This is the first time that Cu speciation has been determined at these temperatures and provides an example of how inclusions can be used as sample cells for the spectroscopic study of fluids at extreme conditions.

History

Publication title

Chemical Geology: An International Journal

Volume

259

Pagination

1-6

ISSN

0009-2541

Department/School

School of Natural Sciences

Publisher

Elsevier Science Bv

Place of publication

Po Box 211, Amsterdam, Netherlands, 1000 Ae

Repository Status

  • Restricted

Socio-economic Objectives

Copper ore exploration

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC