This level is correlated with a seismic unconformity. Sediments are dominated throughout by nannofossil ooze with rare to common foraminifers and siliceous microfossils that include diatoms and radiolarians. Siliciclastic sediment components are largely absent in this open-ocean location. Although the primary objective, high resolution climatic history, could not be met, Site 1169 provides a number of highlights. We were able to develop a useful, although relatively broad, integrated Subantarctic biostratigraphy for the Pliocene and Quaternary involving planktonic foraminifers, calcareous nannofossils, diatoms, radiolarians and organic dinocysts.
Ostracods are also persistently present throughout.
Few previous sites from the Subantarctic region have allowed the development of such an integrated stratigraphy and none previously from the Australian sector of the Southern Ocean. This site also contains the southernmost late Neogene dynocyst record ever found. Representation of much of the late Miocene in unconformities suggests intensification at that time of bottom-water circulation and associated carbonate dissolution on the South Tasman Rise at depths close to 3.5 km. Planktonic microfossil assemblages reflect the influence of both Subantarctic and Temperate water masses in this northern Subantarctic location. These mixed assemblages may indicate shifts in position of the Subtropical Convergence over the region.