Calcareous nannofossil abundance estimates and datums of ODP Leg 189 sites

A major objective of Leg 189 was to date the opening of the Australia-Antarctic Gateway to shallow-water circulation and subsequently to deepwater circulation in the Paleogene. Calcareous nannofossils are the most consistently present, although not necessarily the most abundant fossil group in Paleogene sections, and the shipboard study (Exon, Kennett, Malone, et al., 2001, doi:10.2973/odp.proc.ir.189.2001) showed that they generally provided the most useful age information. This report presents documentation of the stratigraphic distribution of nannofossils in the Paleogene and summarizes useful nannofossil datums, which should facilitate construction of age-depth curves and contribute to an integrated chronology for Leg 189 sediments. Previous Paleogene nannofossil study in this area is that of Edwards and Perch-Nielsen (1975, doi:10.2973/dsdp.proc.29.113.1975).

Silicoflaggelates from ODP Leg 120 on the Kerguelen Plateau

The biostratigraphic distribution and abundance of Eocene to Pleistocene silicoflagellates is documented from Ocean Drilling Program Leg 120 Holes 747A, 748A, 748B, 749B, and 751A on the Central Kerguelen Plateau. Well-preserved silicoflagellates are reported here from the middle Eocene Dictyocha grandis Zone to the Pleistocene Distephanus speculum speculum Zone. Assemblage diversity and abundance is variable, with many intervals either barren of silicoflagellates or containing only limited numbers.

Calcareous nannofossils of the Soithern Coral Sea

Leg 90 of the Deep Sea Drilling Project drilled 18 holes at eight sites (Sites 587-594) on several shallow-water platforms in the southern Coral Sea, Tasman Sea, and southwestern Pacific Ocean. The results from an additional hole (Hole 586B) drilled at Site 586 during Leg 89 are included in this report. Together, these sites form a latitudinal traverse which extends from the equator (Site 586) to 45°S (Site 594) and includes all the major water masses from tropical to subantarctic. Samples recovered at these sites range in age from middle Eocene to late Quaternary. The calcareous nannoplankton biostratigraphy for Leg 90 has divided into two parts: part 1, the Neogene and Quaternary of Sites 586-594. (this chapter); and part 2, the Paleogene of Sites 588, 592, and 593 (Martini, 1986). A slightly modified version of the Martini (1971) standard Tertiary and Quaternary zonation scheme was used to make age determinations on over 700 samples. All of the relevant Neogene and Quaternary zone-defining nannoplankton are present at Sites 586-591 (0°-30°S) but become increasingly rare or are absent at Sites 592-594 (35°-45°S). Species diversity increases southward from the equator (Site 586) and reaches a peak at 20°S (Site 587). A decrease at 25°S (Site 588) and 30°S (Sites 589-591) is followed by an increase in species diversity at 35°S (Site 592). South of 35°S, species diversity again decreases and reaches a low at 45 °S (Site 594). Species diversity for all sites as a group generally increases through the early, middle, and late Miocene, reaches a peak in the early Pliocene, then gradually decreases through the late Pliocene and Quaternary

Silicoflagellates in ODP Leg 108 holes

The occurrence of Cenozoic silicoflagellates at three Ocean Drilling Program (ODP) Holes (660A, 662A, and 667A) was investigated to determine biostratigraphic and relative paleotemperature relations in the tropical Atlantic Ocean. This report presents the data obtained from a study of 37 samples and some preliminary comments on the data. The age of the single sparse assemblage at Hole 660A is late middle Eocene or late Eocene (Dictyocha hexacantha Zone); the sparse to common assemblages of Hole 667A are Oligocene and early Miocene and the common to abundant assemblages of Hole 662A are early Pliocene to Quaternary. Dissolution thinning of silicoflagellates is noted in most samples, even in Hole 662A, which is under the present productive Benguela Current.