The link between oxygen isotope resetting, partial melting, and fluid flow in metamorphic terrains |
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| Authors: | Cartwright & Buick |
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| Institution: | Department of Earth Sciences, Monash University, Clayton, Vic. 3168, Australia.; School of Earth Sciences, LaTrobe University, Bundoora, Vic. 3083, Australia. |
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| Abstract: | A correlation between the style of partial melting and synmeta-morphic fluid flow exists in metapelites from the Mount Lofty Ranges, Reynolds Range, and Omeo Zone (Australia). Mount Lofty Ranges migmatites comprise granitic leucosomes in rocks that are still biotite rich, with no indications of other mafic minerals being formed along with the melts. By contrast, in the Reynolds and Omeo migmatites, garnet, cordierite, and/or spinel formed along with the melts. Oxygen isotope data are most consistent with the Mount Lofty Ranges undergoing significant fluid–rock interaction during regional metamorphism, which may have fluxed fluid-present partial melting. By contrast regional metamorphic fluid flow in the Reynolds Range and Omeo Zone was limited, leading to partial melting via fluid-absent reactions. The style of melting reactions may help to constrain the timing of isotopic resetting and fluid flow in metamorphic terrains, which is currently a contentious issue. |
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