RECORD OF HYDROTHERMAL ACTIVITY IN SEDIME NTS FROM THE MID-ATLANTIC RIDGE SOUTH OF THE AZORES

In order to recognize the distribution of hydrothermal tracers south o f the Azores, a series of cores has been sampled during the GEOFAR cru ise. The distribution of the Mn concentrations shows that the hydrothe rmal influence is maximum within and to the north-west of the Lucky St rike segment. North of the East-Azores Fracture Zone the sediments are enriched in Ba which could be derived from different sources. The che mical composition of the interstitial water shows that water advection is limited. Mn, Cu, Ni fluxes evaluated in one site have increased du ring isotopic stages 4 and 2 and the deglaciation.