The δ¹³C content of calcareous nannofossils as an indicator of Quaternary paleoproductivity in the Southwest Pacific region

Abstract

The δ¹³C signal from calcareous nannofossils in marine sediments may provide a valuable new tool for measuring the ¹³C content of ocean surface waters in the past. Measurements of Quaternary nannofossils from Deep Sea Drilling Project Site 593 on Challenger Plateau, off western New Zealand, indicate that the difference in the δ¹³C of nannofossils and benthic foraminifers, defined as Δ¹³C, is strongly correlated (r = +0.78) with the δ¹⁸O climatic signal, and has promise as an indicator of local paleoproductivity. The isotopic data suggest that, compared with interglacial episodes, there was a general increase in the productivity of surface waters in the southern Tasman Sea during glacial episodes, possibly as a result of intensification of ocean circulation patterns and upwelling currents in the region.

Keywords:

• nannofossils
• foraminifers
• carbon
• isotopes
• oxygen
• Tasman Sea
• Quaternary
• productivity