A review of the Australian-New Zealand sector of the Southern Ocean over the last 30 ka (Aus-INTIMATE project)

• Published in: Quaternary Science Reviews
• Main Authors: Bostock, H. C., Barrows, T. T., Carter, L., Chase, Z., Cortese, G., Dunbar, G. B., Ellwood, M., Hayward, B., Howard, W., Neil, H. L., Noble, T. L., Mackintosh, A., Moss, P. T., Moy, A. D., White, D., Williams, M. J M, Armand, L. K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2013
• Subjects: Antarc*; Antarctic; Antarctica; Iceberg*; Sea ice; Southern Ocean
• Online Access: https://researchers.mq.edu.au/en/publications/498b06b5-6732-4c89-a1eb-252fe40d333d; https://doi.org/10.1016/j.quascirev.2012.07.018; http://www.scopus.com/inward/record.url?scp=84880602819&partnerID=8YFLogxK

The Australia/New Zealand region of the Southern Ocean is influenced by several of the major global water masses of the oceans and is the prime entry point for cold deep waters into the Pacific basin. During the last glacial there was increased sea-ice extent around Antarctica (as far north as 55°S), as well as increased iceberg presence inferred from ice-rafted debris. Evidence from microfossil assemblages suggests that sea surface temperatures (SST) were up to 7°C cooler, consistent with recent estimates of cooling for New Zealand derived from glacier modelling and other terrestrial proxies. The Subtropical Front (STF), Subantarctic Front (SAF) and Polar Front (PF) had migrated north, except where the position of the fronts were controlled bathymetrically. Despite the potential for iron fertilisation by increased dust input into the ocean during the glacial, there is limited evidence for higher total biological productivity in the Pacific sector of the Southern Ocean. The altered oceanic circulation during the glacial also decreased nutrients in the surface waters and affected the outgassing of CO 2 . This contributed to an increased storage of CO 2 in the deep waters and lowering of the carbonate lysocline.During the deglaciation, sea-ice retreat and SST increased rapidly at ~18ka, roughly synchronous with the reinvigoration of deep water circulation in the Southern Ocean and the release of CO 2 stored in the deep waters. The gradient in carbon isotopes (δ 13 C benthic ) between Antarctic Intermediate Water (AAIW) and lower Circumpolar Deep Water (LCDW) was greatest at the start of the deglaciation, suggesting that the AAIW ventilation preceded LCDW ventilation, or there was a significant change in air-sea fractionation of δ 13 C. There was a slight enrichment in δ 18 O planktic , decrease in SSTs and a reduction in intermediate and deep water circulation between ~14 and 12.5kaBP during the Antarctic Cold Reversal (ACR), coincident with glacier advances in the New Zealand Southern Alps and other terrestrial ...