Pressure estimates for amphibolite-facies metamorphism at Plutonic Gold Mine (Plutonic), Marymia Inlier, Western Australia, were recently revised significantly upwards from ∼4 ± 2 kbar/550–600°C to ≥8 kbar/∼600°C, based on the calculated stability fields
for mineral assemblages in garnet-free mafic rocks. These conditions are anomalous in the context of the Yilgarn Craton. Here, we present new mineral equilibria calculations for rare garnet-bearing rock types from Plutonic that confirm those higher pressure estimates, and provide confidence
that the determinations of metamorphic conditions based only on results from metamorphosed mafic rocks are robust and reliable. Taken together, the new estimates (7.3–8.2 kbar/580–590°C) from the garnet-bearing rocks, and the existing results from the mafic rocks, provide evidence
that, most probably during the late Archean, rocks now exposed along the northern margin of the Yilgarn Craton underwent substantial increases in pressure, which was likely followed by rapid exhumation.
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Plutonic Gold Mine;
Document Type: Research Article
CSIRO Mineral Resources Flagship, ARRC, PO Box 1130, Bentley, 6102, WA, Australia
School of Geography, Environment and Earth Science, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
Publication date: October 3, 2014