Xenoliths evidence for a refractory oceanic mantle percolated by basaltic melts beneath the Kerguelen Archipelago

Alkali basalts from the Kerguelen Is. have entrained many mantle peridotites (harzburgites and dunites) in addition to various other ultramafic and mafic xenoliths. The harzburgites and the dunites were equilibrated in the spinel peridotite stability field (T=850-1150 degrees C). They attest to the existence of a metasomatized refractory upper mantle beneath the southeastern province of the Kerguelen Is. To date no fertile mantle lherzolite has been found in this area. Details are discussed concerning the petrology, mineralogy, geochemistry, and formation processes of the harzburgites and dunites found in these islands. (Auth. mod.)