South equatorial current (SEC) driven changes at DSDP site 237, Central Indian Ocean, during the Plio-Pleistocene: Evidence from benthic foraminifera and stable isotopes

作者：Gupta Anil K^*; Das Moumita; Bhaskar K

来源：Journal of Asian Earth Sciences, 2006, 28(4-6): 276-290.

DOI：10.1016/j.seaes.2005.10.006

• Plio-Pleistocene
• benthic foraminifera
• stable isotopes
• DSDP site 237
• Central Indian Ocean
• SEC

This study attempts to analyse paleoceanographic changes in the Central Indian Ocean (Deep Sea Drilling Project Site 237), linked to monsoon variability as well as deep-sea circulation during the Plio-Pleistocene. We used factor and cluster analyses of census data of the 34 most dominant species of benthic foraminifera that enabled us to identify five biofacies: Astrononion umbilicatulum-Uvigerina proboscidea (Au-Up), Pullenia bulloides-Bulimina striata (Pb-Bs), Globocassidulina tumida-Nuttallides umbonifera (Gt-Nu), Gyroidinoides nitidula-Cibicides wuellerstorfi (Gn-Cw) and Cassidulina carinata-Cassidulina laevigata (Cc-Cl) biofacies. Knowledge of the environmental preferences of modem deep-sea benthic foraminifera helped to interpret the results of factor and cluster analyses in combination with oxygen and carbon isotope values. The biofacies indicative of high surface productivity, resulting from a stronger South Equatorial Current (Au-Up and Pb-Bs biofacies), dominate the early Pliocene interval (5.6-4.5 Ma) of global warmth. An intense Indo-Pacific 'biogenic bloom' and strong Oxygen Minimum Zone extended to intermediate depths (similar to 1000-2000 m) over large parts of the Indian Ocean in the early Pliocene. Since 4.5 Ma, the food supply in the Central Indian Ocean dropped and fluctuated while deep waters were corrosive (biofacies Gt-Nu, Gn-Cw). The Pleistocene interval is characterized by an intermediate flux of organic matter (Cc-Cl biofacies).

• 出版日期2006-12-15