Diatom Biostratigraphy: Kerguelen Plateau and Prydz Bay Regions of the Southern Ocean.

Abstract

Samples were examined for diatoms from 22 holes at 11 sites cored by ODP Leg 119 on the Kerguelen Plateau and in Prydz Bay, East Antarctica. Diatoms were observed in Oligocene through Holocene sediments recovered from the Kerguelen Plateau. The diatom flora from the Kerguelen Plateau is characterized by species such as Azpeitia oligocenica, Rocella gelida, Rocella vigilans, and Synedra jouseana in the Oligocene and Crucidenticula nicobarica, Denticulopsis hustedtii, Nitzschia miocenica, and Thalassiosira miocenica in the Miocene. This somewhat cosmopolitan assemblage gives way to a Pliocene and Holocene assemblage characterized by species such as Nitzschia kerguelensis, Thalassiosira inura, and Thalassiosira torokina, which are endemic to the Southern Ocean region. Samples examined from Prydz Bay are generally devoid of diatoms. The exception is Site 739, where diatoms occur sporadically in lower Oligocene and upper Miocene through Quaternary sediments.The Leg 119 diatom biostratigraphic results allow the development of a stratigraphic framework for the Indian sector of the Southern Ocean. This diatom zonation integrates diatom zonations developed previously for other sectors of the Southern Ocean. The zonation proposed here is based on biostratigraphic events of both geographically widespread and endemic species calibrated to the paleomagnetic stratigraphy. As such, this zonation has application throughout the Southern Ocean and allows correlation from the southern high latitudes to the low latitudes.

Late Paleogene Diatom Biostratigraphy and Paleoenvironments of the Northern Norwegian-Greenland Sea

“…Accumulation of diatomaceous sediments, and the diatom assemblages contained therein, was also directly affected by changes in ocean circulation. Siliceous productivity surged in the Southern Ocean in the early Oligocene following this event (Baldauf, 1994;Baldauf and Barron, 1991;Harwood and Maruyama, 1992). There was a similar, though less dramatic, response in the early early Oligocene in the North Atlantic/Labrador Sea region (Baldauf, 1994;Baldauf and Monjanel, 1989).…”

“…Biostratigraphic interpretation of the Paleogene diatom assemblages from Leg 151 comes largely by comparison with diatom assemblages of the Norwegian-Greenland Sea (Schrader and Fenner, Dzinoridze et al, 1978;Fenner, 1985), the North Atlantic and Labrador Sea (Baldauf and Monjanel, 1989), the northwest Pacific region (Baldauf and Barron, 1987;Yanagisawa and Suzuki, 1987), and the antarctic offshore (including Harwood and Maruyama, 1992;Baldauf and Barron, 1991;Fenner, 1978Fenner, , 1984Gombos and Ciesielski, 1983;Hajós, 1976) and nearshore zones Harwood, 1989;Harwood et al, 1989). Many of the low-latitude biostratigraphic markers are very rare or are absent from the high latitudes; nevertheless, published studies of lower latitude Paleogene diatom assemblages, including those described by Palmer (1984), provide worthwhile comparison, particularly for the oldest diatom assemblages of Leg 151.…”

Neogene Diatom Biostratigraphy of the Iceland Sea Site 907

“…1, Table 2). This event occurred later both in the North Pacific (5.4-5.3 Ma) (Barron and Gladenkov, 1995) and in the Southern Ocean (5.1 Ma) (Baldauf and Barron, 1991).…”

Methods

“…1990; Baldauf and Barron, 1991;Harwood and Maruyama, 1992;Censarek and Gersonde, 2002;Zielinski and Gersonde, 2002;Winter and Iwai, 2002). The adopted Neogene diatom zonal scheme used during Expedition 317 follows Cody et al (2008), and the Paleogene zonal scheme follows Harwood and Maruyama (1992).…”