Lipid-biomarker-based sea surface temperature record offshore Tasmania over the last 23 million years

Abstract. The Neogene (23.04–2.58 Ma) is characterised by progressive buildup of ice volume and climate cooling in the Antarctic Northern Hemisphere. Heat moisture delivery to Antarctica is, a large extent, regulated strength meridional temperature gradients. However, evolution Southern Ocean frontal systems remains scarcely studied Neogene. Here, we present first long-term continuous sea surface (SST) record subtropical front area at Drilling Program (ODP) Site 1168 off western Tasmania. This site present, located near (STF), as it was during Neogene, despite 10∘ northward tectonic drift We analysed glycerol dialkyl tetraethers (GDGTs – on 433 samples) alkenones (on 163 reconstructed paleotemperature using TEX86 U37k′ two independent quantitative proxies. Both proxies indicate that experienced temperate ∼ 25 ∘C early Miocene (23–17 Ma), reaching 29 mid-Miocene climatic optimum. stepwise 10 (20–10 ∘C) mid-to-late (12.5–5.0 larger than observed records from lower higher latitudes. From Pliocene modern (5.3–0 STF SST plateaus 15 (3 then decreases 6 (1.3 eventually increases levels around 16 (0 with variability 5∘ compared Miocene. Our results imply latitudinal gradient between Pacific Equator late increased 4 14 ∘C. Meanwhile, margin decreased due amplified margin. implies narrowing contraction warm SSTs expansion subpolar conditions.