Late quaternary palaeoceanography of the circumpolar deep water from the South Tasman Rise

We use sediment cores from the South Tasman Rise (STR) to reconstruct deepwater circulation in the southwest Pacific sector of the Southern Ocean. Sediment cores MD972106 (45° 09′ S, 146° 17′ E, 3310 m water depth) and GC34 (45° 06′ S, 147° 45′ E, 4002 m water depth) preserve records covering the last 160 k yr, with chronology controlled by calibrated accelerator mass spectrometry radiocarbon dates and benthic foraminiferal δ¹⁸O tied to SPECMAP. The STIR benthic foraminiferal δ¹³C records provide new δ¹³C values for Southern Ocean deep water spanning the last 160 kyr at sites unlikely to be affected by variations in productivity. The records establish that glacial benthic foraminifera (Cibicidoides spp.) δ¹³C values are lower relative to interglacial values and are comparable to previous glacial benthic δ¹³C records in the Indian and Pacific sectors of the Southern Ocean. Comparisons of the benthic foraminiferal δ ¹³C time series at the STR are made with the equatorial Pacific (V19-30 and Site 846) and the equatorial Atlantic (GeoB1115). The similarity of benthic δ¹³C records at the STR to the equatorial Pacific suggest the Southern Ocean deep-water mass closely tracked those of the deep Pacific, and the presence of a δ¹³C gradient between the STR and the equatorial Atlantic suggests there was continual production of northern source deep water over the past 160 k yr.