Ultramafic and Associated rocks from southern New Caledonia

by Rodgers, Kerry Anthony

The New Caledonian ultramafic belt is a peridotite-gabbro-granodiorite, alpine-type complex which crops out over the length of the archipelago (some 500 km) as a series of upstanding, perched massifs. The southern portion of the largest of these massifs consists predominantly of partially serpentinised harzburgite containing a dunite-chromitite-eucrite core. Relict cumulus textures, gradational contacts between major lithologic units, and mineral compositions indicate that this core is a gravity differentiate formed at ~1GNm-2, 1200-1400C and constant oxygen fugacity from a mafic magma derived by partial melting of primitive pyrolite, the refractory residue of which constitutes the marzburgites.