MG-FE CARPHOLITES FROM ALUMINOUS SCHISTS IN THE DIAHOT REGION AND IMPLICATIONS FOR PRESERVATION OF HIGH-PRESSURE LOW-TEMPERATURE SCHISTS, NORTHERN NEW-CALEDONIA

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-degrees-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.