Noncalcareous Pelagic Sediments from the Western Pacific: Leg 7, Deep Sea Drilling Project [chapter]

G.R. Heath, R. Moberly
1971 Initial Reports of the Deep Sea Drilling Project, 7  
Noncalcareous pelagic deposits were sampled at four of the Leg 7 sites (61, 65, 66, 67). The Central Basin holes (65 and 66) each passed through more than 100 meters of very pure Tertiary siliceous ooze, indicating that neither the depth relative to the calcite compensation level nor the geographic position relative to the equatorial zone of high biological productivity has varied much since the Middle Eocene at these sites. At site 66, the siliceous ooze is underlain by very fine-grained
more » ... c clay. This deposit spans the Cretaceous-Tertiary boundary. It contains angular quartz shards and illite, suggestive of continental origin, as well as montmorillonite, attapulgite, anorthoclase and earthy ferromanganese oxides, suggestive of mid-ocean ridge volcanism and associated hydrothermal activity. Both the siliceous ooze and pelagic clay contain ferromanganese concretions, implying that they have been oxidized since they were deposited.
doi:10.2973/dsdp.proc.7.118.1971 fatcat:6ezwstcbsbcxpcohd3ccxkp64u