Polar marine diatoms: key markers for Cenozoic environmental shifts. Sedimentary and paleo-environmental reports from Antarctic continental margin (Ross Sea, Wilkes Land and Prydz Bay)

Marine diatoms are sensitive to water-mass distribution and their physical-chemical and biotic preferences affect their biogeographical distribution. In sedimentary records, although altered by secondary processes such as dissolution, they track the primary signal formed in surface water. This make them the major biostratigraphic and environmental markers in the Southern Ocean as they record sea-surface temperatures, sea ice and other parameters usefull for paleoceanographic and paleoclimatic reconstructions (Jordan et al. 2010; Leventer et al., 2010; Crosta, 2011; Escutia et al., 2011). We present three case studies of diatom biostratigrapy and paleoceanographic reconstructions performed on Antarctic sediments recovered from: 1) Pleistocene-Holocene sequences in the Ross Sea and Wilkes Lands, with evidences of glacial/deglacial-interglacial phases (PNRA and IMAGES-CADO Projects in Atlantic and Australian Sectors) (Caburlotto et al., 2010; Tolotti et al., 2013) and 2) Late Eocene-Early Miocene sequences in Prydz Bay, with preliminary micropaleontological results and biostratigraphy related to the greenhouse/ice-house transition (ODP Project in the Indian Sector) (Lagabrielle et al., 2009; Suto et al., 2012). Jordan W.J. & Stikley C.E. 2010. Diatoms as indicators of paleoceanographic events. In: Smol J.P. & Stoermer E.F. Eds., The Diatoms: Applications for the Environmental and Earth Sciences., II Edition., 424-452. Escutia C., Brinkhuis H., Klaus A. & IODP Expedition 318 Scientists. 2011. IODP Expedition 318: From Greenhouse to Icehouse at the Wilkes Land Antarctic Margin. Scientific Drilling, 12, 15-23. Caburlotto A., Lucchi R.G., De Santis L., Macrì P. & Tolotti R. 2010. Sedimentary processes on the Wilkes Land continental rise reflect changes in glacial dynamic and bottom water flow. International Journal of Earth Sciences, 99(4), 909 – 926. Crosta X. 2011. Marine diatoms in polar and sub-polar environments and their application to Late Pleistocene paleoclimate reconstruction. IOP Conf. Series: Earth and Environmental Science, 14, 1-18. Leventer A., Crosta X. & Pike J. 2010. Holocene marine diatom records of environmental change. In: Smol J.P. and Stoermer E. F. Eds., II Edition., 401-423. Lagabrielle Y., Goddéris Y., Donnadieu Y., Malavieille J. & Suarez M. 2009. The tectonic history of Drake Passage and its possible impacts on global climate. Earth and Planetary Science Letters, 279, 197–211. Suto I., Kawamura K., Hagimoto S., Teraishi A. & Tanaka Y. 2012. Changes in upwelling mechanisms drove the evolution of marine organisms. Palaeogeography, Palaeoclimatology, Palaeoecology, 339-341, 39–51. Tolotti R., Salvi C., Salvi G. & Bonci M.C. 2013. Late Quaternary climate variability as recorded by micropalaeontological diatom data and geochemical data in the western Ross Sea, Antarctica. Antarctic Science, 25(6), 804–820.