The recovery of hydrothermal sediments at depth beneath the mounds of hydrothermal origin during a brief period of drilling on Deep Sea Drilling Project (DSDP) Leg 54 provided some evidence suggesting that hydrothermal material may be pervasive over a relatively large region inclusive of the mounds but also incorporating adjacent seafloor presently covered by pelagic sediments. As a result of the incomplete recovery of sediments at some sites and the poor recovery of basement rocks during Leg 54, it was suggested that a more carefully planned program be designed to drill a broader range of sites in the Galapagos mounds field. The major objectives of the first part of Leg 70 were to collect data and sediment representative of the hydrothermal mounds and ridges located about 20 km south of the Galapagos spreading axis.

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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.