GEOCHEMISTRY OF DEEP-SEA SURFACE SEDIMENTS FROM THE PACIFIC MANGANESE-NODULE PROVINCE NEAR CLARION ISLAND, MEXICO

Surface sediments from the Pacific oceanic area near Clarion Island, M exico were studied. Microscopic observations show that the sediments a re formed mainly by materials from submarine vulcanism, and biogenic, authigenic, and clay materials in different proportions according to t he physiographic studied regions (the EPR region at 21-degrees-N, the high density nodule region (HDN), and an intermediate region). Compare d to average Pacific pelagic clays, sediments are enriched in Mn and s ome trace metals, such as Ni, and Co in the studied area. The sediment s show particular chemical characteristics that apparently reflect the processes taking place in each particular region. A cluster analysis of the chemical data shows the presence of 4 different geochemical gro ups, namely. Group 1 has characteristics associated to hydrothermal pr ocesses, Group 2 has a high hydrothermal influence, with the highest c oncentration of Zn in sediments; Group 3 corresponds to the north part of the high density nodule region and the north of the intermediate r egion, where nodules richer in Fe and Co were present; and Group 4 cor responds to the south part of the intermediate region and the south pa rt of the high density nodule area, where nodules with higher concentr ation of Mn, Cu, and Ni were reported.