Fe-Ni-Cu sulphides of abyssal peridotites from the MARK area (Mid-Atlanticridge, 20-24 degrees N)

Abyssal peridotites from the MARK area (Mid-Atlantic ridge), studied from 2 7 samples. contain magmatic sulphides of mantle origin. The magmatic parage nesis (pentlandite + pyrrhorite + chalcopyrite) was protected in some inclu sions. All the intergranular sulphides have been affected by hydrothermal t ransformations. In spite of these transformations, two populations of sulph ides can be identified: (1) grains having survived the partial melting even t in situ; (2) grains precipitated during or after the partial melting. ((C ) 1999 Academie des sciences/Editions scientifiques et medicales Elsevier S AS.)