Palaeoceanographical changes recorded by Cenozoic deep-sea ostracod assemblages from the South Atlantic and Southern Ocean (ODP sites 1087 and 1088)

Author(s): Majoran, Stefan; Dingle, Richard V.
Author Affiliation(s): Primary:
University of Copenhagen, Geological Institute, Copenhagen, Denmark
Volume Title: Lethaia
Source: Lethaia, 34(1), p.63-83. Publisher: Taylor & Francis on licence from the Lethaia Foundation, Oslo, Norway. ISSN: 0024-1164 CODEN: LETHAT
Note: In English. Includes appendix. 72 refs.; illus., incl. 5 tables, sketch map
Summary: Cenozoic palaeoceanography of the SE Atlantic and Southern Oceans has been investigated using Late Eocene/Early Oligocene to Quaternary ostracod assemblages from 49 samples of ODP Sites 1087 and 1088. The overall abundance of ostracods is relatively low and there is an apparently high level of endemism. Three major changes in the faunal assemblages are identified at Site 1087 (A, B, and C) and two at Site 1088 (B' and C'). The assemblage boundaries, detected on the basis of stepwise changes in the abundance, diversity, dominance, endemism, faunal turnover, and relative abundance of common taxa, coincide broadly with previously identified, ostracod-based paleoceanographical 'events' discussed by Benson and co-workers over the last two decades. The data do not extend sufficiently far back to record the initiation of Assemblage A, but the faunal change between Assemblages A and B, marked by a decline in abundance, species diversity and faunal turnover, occurs within the middle Miocene. It coincides with a previously documented palaeoceanographical "event" at 16-14 Ma which is suggested to possibly be related to the initiation of North Atlantic Deep Water (NADW) production and/or an expansion of the East Antarctic ice sheet. Assemblage B'1 and B'2 sub-assemblage boundary cannot be related to any previously documented faunal change in deep-sea ostracods. Changes associated with the boundaries between Assemblages B and C, and B' and C' include a decrease in diversity and abundance. Two strong turnover peaks occur near the B'/C' boundary at Site 1088. The B/C and B'/C' boundaries coincide with a previously documented mid-Pliocene "event" (3.5 Ma) which may be linked to closure of the Straits of Panama and increased production of NADW. The increase in NADW may have lead to increased production of Antarctic Intermediate Water (AAIW) and Antarctic Bottom Water (AABW). On the other hand, fluctuations in size of the Antarctic ice sheet during possible Pliocene warm periods could indirectly be responsible for the observed mid-Pliocene faunal changes. (Mod. auth. abstr.)
Year of Publication: 2001
Research Program: ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Antarctic Bottom Water; Antarctic Intermediate Water; Antarctic Ocean; Antarctic ice sheet; Antarctica; Arthropoda; Assemblages; Atlantic Ocean; Atlanticythere; Biogeography; Cenozoic; Crustacea; Currents; Deep-sea environment; Dutoitella; Endemic taxa; Glacial environment; Glacial geology; Glaciomarine environment; Henryhowella; Ice sheets; Invertebrata; Krithe; Leg 175; Leg 177; Mandibulata; Marine environment; Microfossils; North Atlantic Deep Water; ODP Site 1087; ODP Site 1088; Ocean Drilling Program; Ocean currents; Ostracoda; Paleo-oceanography; Paleocirculation; Paleoclimatology; Paleocurrents; Paleoecology; Pennyella; Rugocythereis; South Atlantic; Southern Ocean; Taxonomy
Coordinates: S312754 S312754 E0151839 E0151839
S410810 S410810 E0133346 E0133346
Record ID: 2002051653
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.