Quaternary isotope stratigraphy of Hole 593, Challenger Plateau, South Tasman Sea: preliminary observations based on foraminifers and calcareous nannofossils.

Abstract

A moderate-resolution isotope stratigraphy (with an average of one sample per 17 500 yr.) derived from the benthic foraminifer Uvigerina (or Cibicides), the planktonic foraminifer Globigerina bulloides, and calcareous nannofossil concentrates is presented for the entire Quaternary (and latest Pliocene) section of mid-upper bathyal calcareous oozes from DSDP Site 593, western Challenger Plateau, south Tasman Sea. The standard late Quaternary isotope stages 1 to 24 are mainly resolvable. Significant excursions in both delta 18O and delta 13C values at various times during the Quaternary are suggested to be due to periodic, fundamental changes in ocean circulation properties over the plateau. Intensified upwelling of Antarctic Intermediate Waters during several glacial periods is indicated by the convergence of benthic and planktonic foraminiferal delta 18O data, and productivity variations may account for certain delta 13C spikes in the record. With increasingly higher resolution analysis this core will provide a useful Quaternary isotope reference section for southern temperate waters in the southwest Pacific, centered on New Zealand. -from Authors