Annotated record of the detailed examination of Mn deposits from DSDP Leg 70 (Holes 506, 506B, 506C, 507C, 507D, 507F, 509, 509B)

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.