Faunal changes in Cenozoic deep-sea ostracod assemblages from the South Atlantic and the Southern Ocean and their palaeoceanographical implications
Titel:
Faunal changes in Cenozoic deep-sea ostracod assemblages from the South Atlantic and the Southern Ocean and their palaeoceanographical implications
Auteur:
Majoran, Stefan Dingle, Richard V.
Verschenen in:
GFF
Paginering:
Jaargang 124 (2002) nr. 1 pagina's 19-26
Jaar:
2002-03-01
Inhoud:
The Cenozoic palaeoceanographical history of the South Atlantic and the Southern Ocean is summarised on the basis of changes in the ostracod faunas of DSDP/ODP Sites 329, 513, 689, 699, 1087 and 1088. The results are mainly compared with the global palaeoceanographical history of Benson. The present study failed to find strong evidence for a sudden psychrospheric event (Sites 689 and 699) in the late Eocene, but there is, however, a decrease in abundance and diversity of ostracods from the mid-/late Eocene to the Oligocene at Sites 689 and 699. This suggests a more gradual palaeoceanographical change over a relatively long time interval. Mid-Miocene faunal changes occur at Site 1087 and coincide with the 16-14 Ma event of Benson. However, the faunal changes are, in contrast to Benson, here marked by a decline in abundance, diversity and faunal turnover. The local differences in faunal changes in mid-Miocene deep-sea ostracod faunas may be related to the initiation of NADW and/or a major expansion of the Antarctic ice sheet. We found little or no evidence for the 6.3-4.9 Ma event, which Benson recorded and related to the effects of a series of events such as the Messinian Salinity Crisis and increased glaciation on Antarctica. Similar to Benson's global data, we have also found a major faunal turnover at Sites 1087 and 1088 at 3.5 Ma. This is possibly related to the effects of a closure of the Straits of Panama, increased production of NADW, AAIW and AABW, and/or a major deglaciation of the Antarctica in the mid-Pliocene.
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