Land–sea correlations in the Australian region: 460 ka of changes recorded in a deep-sea core offshore Tasmania. Part 2: the marine compared with the terrestrial record

Abstract

We present an array of new proxy data and review existing ones from core Fr1/94-GC3 from the East Tasman Plateau. This core is positioned at the southern extreme of the East Australia Current and simultaneously records changes in both oceanography and environments both in offshore and in southeastern Australia. Microfossils, including planktonic and benthic foraminifera, ostracods, coccoliths and radiolarians, were studied to interpret palaeo-oceanographic changes. Sea-surface temperature was estimated using planktonic foraminifera, alkenones and radiolaria. From the silicate sediment fraction, the mean grain size of quartz grains was measured to detect the changes in wind strength. An XRF scan of the entire core was used to determine the elemental composition to identify provenance of the sediment. We also compare these data with a pollen record from the same core provided in an accompanying article that provides the longest well-dated record of vegetation change in southeastern Australia. In an area of slow sedimentation, Fr1/94-GC3 provides a continuous record of change in southeastern Australia and the southern Tasman Sea over approximately the last 460 ka. We determine that the East Australian Current varied in intensity through time and did not reach the core site during glacial periods but was present east of Tasmania during all interglacial periods. The four glacial–interglacial periods recorded at the site vary distinctly in character, with Marine Isotope Stage (MIS) 9 being the warmest and MIS 5 the longest. Through time, glacial periods have progressively become warmer and shorter. Deposition of airborne dust at the core site is more substantial during interglacial periods than glacials and is believed to derive from mainland Australia and not Tasmania. It is likely that the source and direction of the dust plume varied significantly with the wind regimes between glacials and interglacials as mean effective precipitation changed.