Linkage of North Atlantic and Southern Ocean deep-water circulation during glacial intervals

Abstract

The Antarctic Circumpolar Current (ACC) is one of the major current systems in the world ocean, affecting circulation in all of the major ocean basins. The ACC flows eastwards around Antarctica from the surface to ∼4,000 m depth with a transport on the order of 125 Sverdrups1. Deep-sea benthic foraminifera from one piston core (E49–18) from the south-east Indian Ocean sector of the Southern Ocean were analysed to determine deep-water-mass-circulation conditions within the ACC during the late Quaternary. I report here that benthic foraminiferal faunal patterns closely match Northern Hemisphere ice-volume changes shown by planktonic foraminiferal oxygen-isotopic stratigraphy. The glacial–interglacial faunal oscillations are interpreted to reflect the presence of a deep-water mass in the ACC during glacial times which differs from modern Circumpolar Deep Water. I suggest that deep-water circulation changes within the ACC during the interval 440,000 to the present are directly linked to changes in North Atlantic Deep Water (NADW) circulation.