Hydrothermal impact on sediments of Red-Sea deeps by the study of some trace metals.

The Cu, Ni, Fe, Cr and Zr concentrations were evaluated to study the influe nce of hydrothermal activity on the sediments of six Red-Sea deeps. Compari son between the Ni/Fe and Cu/Fe ratios supports distinction between hydroth ermal and non-hydrothermal sediments, whereas anti-correlation between Zr a nd Cr concentrations results from hydrothermal influence. The results allow us to envisage that the sediments of the Suakin Deep did not undergo a hyd rothermal activity and that this hydrothermal influence was weak in the Val divia Deep. The sediments of Port-Soudan Deep recorded a hydrothermal activ ity, whereas this activity was the strongest in the Thetis and Atlantis II deeps. (C) 2000 Ifremer/CNRS/IRD/Editions scientifiques et medicales Elsevi er SAS.