Mg–Fe carpholites from aluminous schists in the Diahot region and implications for preservation of high-pressure/low-temperature schists, northern New Caledonia |
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| Authors: | P M BLACK P MAURIZOT E D GHENT M Z STOUT |
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| Institution: | Department of Geology, University of Auckland, PB92019, Auckland, New Zealand;Bureau de Recherches Geologiques et Minierés, BP 56, Noumea, New Caledonia;Department of Geology and Geophysics, University of Calgary, Calgary, Alberta Canada T2N 1N4 |
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| Abstract: | Abstract Mg–Fe carpholite is widespread in the Diahot region of New Caledonia in highly aluminous schists and as veins in what was originally a clay-rich hydrothermal alteration envelope about massive suphide deposits. These carpholites have Fe/(Fe + Mg) ratios of 0.03–0.65 and no significant Mn component. Mg-carpholite + quartz occur in assemblages with chlorite or pyrophyllite, pyrophyllite + kaolinite and pyrophyllite + diaspore. Temperatures of 230–320° C and minimum pressures of 7 kbar are indicated for the Mg–Fe carpholite-bearing rocks. The regional distribution of aragonite and Mg–Fe carpholite parallel to a major zone of dominantly transcurrent movement and oblique to the trend of the subduction complex indicates the high- P /low- T schists owe their rapid uplift and preservation to the vertical component of the transcurrent faulting. |
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| Keywords: | high-P/low-T metamorphism Mg–Fe carpholite phase equilibria in aluminous schists pyrophyllite uplift mechanisms |
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