Main chemical elements concentration in manganese nodules retrieved in the northeast equatorial Pacific during the R/V Valdivia VA-13/2 campaign

Manganese nodule deposits exhibit variabity in distribution, deposit density, nodule morphology, and chemistry on scales of meters to thousands of kilometers. The Challenger Expedition recognized sufficient variation in nodule form to permit identification of a station location by inspection of a specimen nodule. The existence of a copper/nickel-rich nodule belt north of the equator in the Pacific was recognized in the 1950s and its character emphasized by early work of the IDOE Manganese Nodule Project. Through field work by the IDOE Project and by research programs in Germany and France, it has been posible to examine the detail of variability within well-defined regional patterns. Data from four small areas studied by the R/V Kana Keoki , R/V Moana Wave , and the F/S Valdivia , plus regional data within the Pacific equatorial nodule belt, show that the deposit variability is as high on a local as on a regional scale. An area 20 x 20 nautical miles, within the abyssal hill region of the northern Central Pacific, has been sampled intensively by R/V Valdivia during the VA-13/2 campaign. Selected manganese nodules retrieved either from free fall or box grabs were later analysed in laboratory using atomic absorption spectroscopy (AAS). It is likely that the samples were dried at 110°C for 24 hours and then ground for analytical purposes.