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High-temperature carbonate minerals in the Stillwater Complex, Montana, USA

Publication ,  Journal Article
Aird, HM; Boudreau, AE
Published in: Contributions to Mineralogy and Petrology
October 1, 2013

High-temperature carbonate minerals have been observed in association with sulfide minerals below the platiniferous Johns-Manville (J-M) reef of the Stillwater Complex in a stratigraphic section that has been previously shown to be characterized by unusually Cl-rich apatite. The carbonate assemblage consists of dolomite with exsolved calcite in contact with sulfide minerals: chalcopyrite and pyrrhotite in the Peridotite Zone; and pyrrhotite with pentlandite, pyrite and chalcopyrite in Gabbronorite Zone I of the Lower Banded Series. A reaction rim surrounds the carbonate-sulfide assemblages, showing an alteration of the host orthopyroxene to a more calcium-enriched, Fe-depleted pyroxene. The calcite-dolomite geothermometer yields a minimum formation temperature as high as 950 °C for the unmixed assemblages. Iron and manganese concentrations exceed the range seen in carbonatite and mantle xenolith carbonates and are distinctly different from the nearly pure end-member carbonates associated with greenschist-grade (and lower) assemblages (e.g., carbonate veins in serpentinite) that occur locally throughout the complex. The association of high-temperature carbonates with sulfides beneath the J-M reef supports the hydromagmatic theory which involves a late-stage chloride-carbonate fluid percolating upwards, dissolving PGE and sulfides and redepositing them at a higher stratigraphic level. Characterization of the processes which form strategically important metal deposits, such as the J-M reef of the Stillwater Complex and the analogous Merensky reef of the Bushveld Complex in South Africa, could potentially lead to better exploration models and, more broadly, a deeper understanding of the cooling and compositional evolution of large bodies of ultramafic and mafic magma and of carbonatites, on both a local and a regional scale. © 2013 Springer-Verlag Berlin Heidelberg.

Duke Scholars

Published In

Contributions to Mineralogy and Petrology

DOI

ISSN

0010-7999

Publication Date

October 1, 2013

Volume

166

Issue

4

Start / End Page

1143 / 1160

Related Subject Headings

  • Energy
  • 4019 Resources engineering and extractive metallurgy
  • 3705 Geology
  • 3703 Geochemistry
  • 0499 Other Earth Sciences
  • 0403 Geology
  • 0402 Geochemistry
 

Citation

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MLA
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Aird, H. M., & Boudreau, A. E. (2013). High-temperature carbonate minerals in the Stillwater Complex, Montana, USA. Contributions to Mineralogy and Petrology, 166(4), 1143–1160. https://doi.org/10.1007/s00410-013-0913-2
Aird, H. M., and A. E. Boudreau. “High-temperature carbonate minerals in the Stillwater Complex, Montana, USA.” Contributions to Mineralogy and Petrology 166, no. 4 (October 1, 2013): 1143–60. https://doi.org/10.1007/s00410-013-0913-2.
Aird HM, Boudreau AE. High-temperature carbonate minerals in the Stillwater Complex, Montana, USA. Contributions to Mineralogy and Petrology. 2013 Oct 1;166(4):1143–60.
Aird, H. M., and A. E. Boudreau. “High-temperature carbonate minerals in the Stillwater Complex, Montana, USA.” Contributions to Mineralogy and Petrology, vol. 166, no. 4, Oct. 2013, pp. 1143–60. Scopus, doi:10.1007/s00410-013-0913-2.
Aird HM, Boudreau AE. High-temperature carbonate minerals in the Stillwater Complex, Montana, USA. Contributions to Mineralogy and Petrology. 2013 Oct 1;166(4):1143–1160.
Journal cover image

Published In

Contributions to Mineralogy and Petrology

DOI

ISSN

0010-7999

Publication Date

October 1, 2013

Volume

166

Issue

4

Start / End Page

1143 / 1160

Related Subject Headings

  • Energy
  • 4019 Resources engineering and extractive metallurgy
  • 3705 Geology
  • 3703 Geochemistry
  • 0499 Other Earth Sciences
  • 0403 Geology
  • 0402 Geochemistry