During Leg 27 five sites were drilled in the eastern Indian Ocean, four in abyssal plains near the western margin of Australia and one in the Timor Trough. Abyssal plain sediments are divided into two major units: (1) a lower, acoustically transparent layer of relatively uniform thickness draped over basaltic basement and (2) a horizontally layered sequence of highly variable thickness filling low areas on the surface of the transparent layer. The transparent layer, ranging in age from Upper Jurassic to Upper Cretaceous, consists chiefly of dark gray, siliceous clays and claystones with minor zeolitic clay and nannofossil ooze. Sedimentation rates are between 5 and 30 m/m.y. being highest in the Lower Cretaceous. Upper Cretaceous sediment are sparse or absent. The relatively high sedimentation rates for pelagic clay are probably due to the proximity of the Australian continent. The layered unit consists of calcareous oozes and lesser zeolitic clay and radiolarian ooze, all of Cenozoic age. Many of the oozes contain shallow-water foraminifers and graded sequences suggesting deposition by mass transport.
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1989 NOAA-NCEI compiled the NOAA-MMS Marine Minerals Geochemical Database from journal articles, technical reports and unpublished sources from other institutions.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.
Supplement to: Robinson, Paul T; Thayer, Julie A; Cook, Peter J; McKnight, Brian K (1974): Lithology of Mesozoic and Cenozoic Sediments of the Eastern Indian Ocean, Leg 27, Deep Sea Drilling Project. In: Veevers, J.J.; Heirtzler, J.R.; et al., Initial Reports of the Deep Sea Drilling Project, Initial Reports of the Deep Sea Drilling Project, U.S. Government Printing Office, XXVII, 1001-1047
