Preliminary analysis of exploration data from pacific deposits of manganese nodules

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Abstract
Ocean Minerals Company (OMCO) carried out 16 expeditions to the Clarion‐Clipperton region of the northeastern tropical Pacific between 1978 and 1981. During these cruises OMCO collected substantial data through acoustic profiling, video and photographic imaging of the seabed, and sampling of the deposits with dredges, box cores, and free‐fall grab samplers. In 1990 the samples, photographs, technical reports, and computer data bases that resulted from this work were archived at the Marine Minerals Technology Center at the University of Hawaii. This examination focuses on the biological observations made from the more than 10,000 photographs of the seabed and the manganese nodule size distributions and ore‐grade data from the free‐fall grab recoveries. Regional trends are evident for all three data types. The seabed photographs show significant geographical trends, with greater abundances of organisms being noted in the northeastern extreme of the region, decreasing toward the southwest (11.4 to 2.7 observations per 100 m2; 460 to 190 g per 100 m2). Ore‐grade assays performed by OMCO resulted in average values for the major nodule components that are very similar to published results for the area, but which have much smaller standard deviations than the published numbers. Preliminary geostatistical analysis of the ore‐grade data shows that, in addition to high local variability, some deposit continuity for compositions and abundance is apparent over areas with dimensions of approximately 100 nautical miles (NM). The nodule size distributions suggest that the ratio of the nodule burial rates to growth rates systematically decreases over the same range (1.95 to 1.14 nodules buried per 1 cm of growth per m2 of seabed area).