Upper Cretaceous and Cenozoic calcareous nannofossils of the Kerguelen Plateau (Southern Indian Ocean) and Prydz Bay (East Antarctica)

Abstract

ODP Leg 119 drilled 11 sites on the Kerguelen Plateau. Species diversity of calcareous nannofossils was low (about a dozen) in the southern Indian Ocean in the late Cretaceous. High-latitiude nannofloral characteristics are apparent after the Cretaceous/Tertiary boundary extinctions. Cold climatic conditions limited Oligocene calcareous nannofossil assemblages to fewer than a dozen species. Only a few species of calcareous nannofossils were found in the Miocene sequences. Further deterioration of climate in the late Neogene essentially excluded calcareous nannoplankton from the Southern Ocean. Significantly warmer water conditions during part of the early-middle Pleistocene were inferred by a few lower-middle Pleistocene calcareous nannofossil species found on the Kerguelen Plateau. The calcareous nannofossil zonation of Roth (1978) can be applied to the upper Cretaceous section recovered at Site 738, and the zonation of Okada and Bukry (1980) can be applied without much difficulty to the Paleocene to middle Eocene sequences from the Kerguelen Plateau. However, some conventional upper Paleogene markers are not useful for southern high latitudes, whereas a few nonconventional species events are useful for subdividing the upper Paleogene sequences. Calcareous nannofossil zonations remain virtually unworkable for the Neogene in the high-latitude southern Indian Ocean. -from Authors