| Abstract |
Analyses of polymetallic nodules from the central south Pacific and from the underlying sediments indicate that nodule abundance is at least partly related to the degree of carbonate dissolution, which, it self, is strongly influenced by the flow o f the Antarctic Bottom Water. The greatest nodule abundance is generally encountered in a 300 to 400 meter thick water layer situated between the lysocline and the calcite compensation depth levels.This range of depth is the first and main controlling factor of abundance. Inside this range, the bathymetry represents a secondary factor influencing both abundance and grade.Some correlations appear locally between nodule grade and abundance.Nodule grade seems to be generally related to the bottom morphology. Ni, Cu and Mn grades are positively correlated and are highest i n topographic lows.On the contrary, Co and Cu are negatively correlated and Co presents higher grade on topographic highs. [NOT CONTROLLED OCR] |
