Ocean productivity and temperature across the subtropical front, south of New Zealand, over the last deglaciation

12th International Conference on Paleoceanography (ICP12), 29 August - 2 September 2016, UtrechtThe Subtropical Front (STF) separates warm and saltier subtropical waters from the cold, less saline and nutrient-rich subantarctic waters of the Southern Ocean. Determining its past north-south movements is crucial, for instance, to understand the role of such frontal systems on ocean productivity of the subantarctic region, asopposed to increased Fe availability. Three marine cores were recovered south of New Zealand, along a latitudinal transect crossing the modern STF. We have analysed long chain alkenones, as markers of coccolithophore productivity and past sea surface temperatures, n-alkanes and n-alcohols, as proxies for continental input and dust-derived iron and long chain diols and esterols as tracers of diatom productivity. Reconstructed SST changes show a 3-4°C temperature gradient during the Holocene between the corelocations, while during the last glacial period no temperature gradient existed, with 8-9°C recorded at all three sites. This suggests a northward displacement of the STF during the cold glacial climate and the prevalence of subantarctic waters at the core sites, between 47 and 50.5°S. The SST evolution will be complemented with a temperature reconstruction based on the relative distribution of isoprenoid GDGTs (the TEX86 index) and compared with records of past productivity and the input of continental materialPeer Reviewe