Late Pliocene-quaternary biostratigraphy and climatic change in DSDP 208, Lord Howe rise

Abstract

Site 208 from Leg 21 of the Deep Sea Drilling Project contains a well preserved and almost complete sequence of Pliocene and Pleistocene planktic foraminifera and calcareous nannoplankton. The upper 42.5 m of sediment has been analysed at 50 cm intervals. Several major cold episodes are recognised. The strongest occur at 39 m, 27 m and about 11 m. The first of these may represent the onset of major continental glaciation in the Late Pliocene, about 3.0 m.y. ago. Oceanic palaeo-temperatures were found to vary by at least 8 °C, implying a latitudinal water mass movement of about 10°. The biostratigraphy has strong affinities with Tropical zonations, except that two species whose extinctions are used elsewhere as datum planes were found to occur here much higher in the sequence. They were Globorotalia rnulticamerata and Globigerinoides fistulosus. Four coiling reversals were found in Pulleniatina obliquiloculata in the Pleistocene and were apparently unrelated to climate. Dates for these reversals agree closely with those found elsewhere. They may be useful datum points for Early Pleistocene correlation.