Glacial deep water geometry: South Atlantic benthic foraminiferal Cd/Ca and δ13C evidence

Abstract

A depth transect of cores from 1268 to 3909 m water depth in the western South Atlantic are ideally situated to monitor the interocean exchange of deep water and variations in the relative strength of northern and southern sources of deep water production. Benthic foraminiferal Cd/Ca and δ13C data suggest that Glacial North Atlantic Intermediate Water (GNAIW) extended at least as far south as 28°C in the western South Atlantic. The core of nutrient-depleted water was situated at ∼1500 m, above and below water masses with higher nutrient concentrations. When examined in conjunction with published paired Cd/Ca and δ13C from intermediate depth cores from other basins, it appears that the extent of GNAIW influence on the intermediate waters of the world's oceans was less than suggested previously. Differentiating among possible pathways for the glacial deep ocean (> 3 km) requires a better understanding of the controls on Cd/Ca and δ13C values of benthic foraminifera.