ELEMENT SUPPLY TO SURFACE MANGANESE NODULES ALONG THE AITUTAKI-JARVISTRANSECT, SOUTH-PACIFIC

Supply of metals to manganese nodules in the south equatorial Pacific is heavily dependent on variations in biological productivity. In the northern part of the Aitutaki-Jarvis transect, under high biological p roductivity in the surface waters, there is a high flux of Mn, Ni, Cu and Zn to the nodules diagenetically cycled through the interstitial w aters of the uppermost sediments, together, in the nodules, with the f ormation of 10 angstrom manganite. To the south of the high productivi ty zone, these elements decrease in the nodules at the expense of Fe, Co and Pb of hydrogenetic provenance and deltaMnO2 is more abundant. H owever, nodule compositions also reflect the position of the deposits relative to the carbonate compensation depth (CCD), which deepens nort hwards throughout the region, with Mn, Ni, Cu and Zn being enriched in 10 angstrom manganite bearing nodules from near the CCD under high pr oductivity waters and Fe, Co and Pb being more abundant in X-ray amorp hous or deltaMnO2-bearing nodules away from the CCD and/or in the sout h of the transect under low productivity waters.