In order to evaluate the possible influence of hydrothermal activity on Fe-Mn coatings found on the surfaces of basaltic rocks in the median part of Transform Fault "A", a few samples collected in different structural settings less than 2 km away from the hydrothermal fields. They were analysed along with samples further West in the Transform Valley (sample ARP 74-13-23) and from the top of the deepestescarpment of the inner West wall of the Rift Valley near 36'50'N (sample cyp 74-31-40). Chemical analyses were done by arc spectrometry using an ARL quantometer were made at the University of Strasbourg. This method consists of melting the sample in a mixture of lithium tetraborate and then introducing the melt into in a glycolated solvent prior analysis. Trace elements were determined using graphite discs . Na and K were determined by emission spectrometry (precision of +- 2.0%).

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.This dataset represents the digitized Table 3, pp. 707 of the related publication.