Stable isotope (carbonates), organic carbon, calcium carbonate and occurrence of coccoliths at DSDP Hole 71-511

They have been studied via carbonate, organic carbon, stable isotope, nannofloral, and ultrastructural analysis in an attempt to determine their mode of origin.

Nannofossil diversity and preservation suggest that selective dissolution or diagenesis did not produce the interbedded coccolith-rich and coccolith-poor layers, nor did blooms of opportunistic species play a role. Stable isotope measurements of carbonate do not adequately constrain the origin of the cyclicity; however, the d13C data suggest that the more nannofossil-rich intervals may be due to higher nutrient supply and overturn of deeper waters at the site rather than influxes of well-oxygenated waters into an otherwise anoxic environment.