Annotated record of the detailed examination of Mn deposits from DSDP Leg 33 (Holes 314, 315A, 317A, 318)

The Manihiki Plateau is an elevated area of shallow oceanic crust in the South Pacific; it was formed during Early Cretaceous time by profuse outpourings of basalt. DSDP Holes 317, 317A, and 317B, on which this account is based, are situated in a basinal area on the so called High Plateau, the shallowest part of the volcanic edifice, where depths range between 2000 and 3000 meters. The oldest sediments cored are Lower Cretaceous greenish-black volcaniclastics traversed by reddish-purple clay seams; these deposits commonly show evidence of redeposition, but the only possible shallow-water remains found are very rare bryozoan and echinoderm fragments.