Recent studies on marine ferromanganese nodules have suggested a relationship between their growth rate and their chemical composition. The suggestion is based on the hypothesis that the metals in nodules have two sources of supply: bottom seawater (hydrogenous) and sediment pore water (diagenetic). The diagenetic source calls for upward diffusion of Mn mobilized in a deeper, low Eh zone of the sediment column and its subsequent precipitation in an oxidized surface zone. Addition of the remobilized Mn to surface nodules would augment their accretion rate. It would also render the oxide layers to contain higher Mn/Fe ratios than layers resulting from hydrogenous precipitation. We report here a radiometrically determined accretion rate of 168±24 mm/Myr for a deep-sea manganese nodule from the Peru Basin in the Pacific. This rate is about two orders of magnitude higher than that frequently found in nodules of deep-sea origin, and emphasizes the importance of sediment diagenetic processes on the growth of manganese concretions.

From 1983 until 1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions. At the time it was the most extended data compilation on ferromanganese deposits world wide. Initially published in a proprietary format incompatible with present day standards it was jointly decided by AWI and NOAA to transcribe this legacy data into PANGAEA. This transfer is augmented by a careful checking of the original sources when available and the encoding of ancillary information (sample description, method of analysis...) not present in the NOAA-MMS database.

Supplement to: Reyss, Jean-Louis; Marchig, Vesna; Ku, Teh-Lung (1982): Rapid growth of a deep-sea manganese nodule. Nature, 295(5848), 401-403