Neogene circulation in the southern Indian Ocean: evidence from benthic foraminifers, carbonate data, and stable isotope analyses (Site 751)

Abstract

Lower Miocene through upper Pleistocene benthic foraminifer assemblage records from ODP Site 751 were combined with benthic and planktonic foraminifer oxygen and carbon isotope records and high-resolution CaCO3 data from the same site. Implications for the Neogene productivity and paleoceanography of the southern Indian Ocean are discussed. Coinciding with a lower middle Miocene hiatus from 14.2 to 13.4 Ma, there was a rapid increase in benthic δ18O values by 1.2‰. A drastic change in benthic foraminifer faunas coincided with a hiatus from 8.4 to 5.9 Ma. Shortly after this hiatus, the CaCO3 content of the sediments dropped from 75% to 0%. From that time (~5.8 Ma) through the early Pliocene, Site 751 has been situated beneath a high biogenic siliceous productivity zone. Carbonate contents of upper Pliocene and Pleistocene sediments vary between 20% and 70%. -from Authors