Istituto di Scienze Marine     
Giuliani S., Capotondi L., Maffioli P., Langone L., Giglio F., Yam R., Frignani M., Ravaioli M. Paleoenvironmental changes in the Paci fi c sector of the Southern Ocean Antarctica)during the past 2.6 Ma. In: Global and Planetary Change, vol. 77 pp. 34 - 48. Elsevier B.V, 2011.
Two deep-sea cores (ANTA95-157 and ANTA98-1) were collected in the Paci fi c sector of the Southern Ocean across the present-day position of the Antarctic Polar Front Zone (APFZ) to document paleoenvironmental changes during the last 2.60 Ma. The stratigraphic framework was established using a combination of diatom marker species, Accelerator Mass Spectrometry (AMS) 14 C datings, magnetostratigraphy, and oxygen stable isotopes. The study was based on carbon and nitrogen isotopes of diatom-bound organic matter, dry bulk density, magnetic susceptibility, carbonates and biogenic silica contents. Large continental inputs were recorded during glacial periods and major iceberg melting occurred at 2.45 Ma and during the Middle Pleistocene Revolution (MPR) time interval. Diatom production increased during the Early Pleistocene and remained signi fi cant ever since, with the exception of the MPR period and immediately before. Lower glacial diatom productivity linked to higher nitrogen utilization might have characterized the period between Marine Isotope Stages (MISs) 15-13 (0.6 and 0.5 Ma), whereas succeeding glacial stages experienced an increase of diatom productivity promoted by the in fl ow of nutrient-rich deep waters. The low diatom production observed during interglacial stage 11 could be explained with a southward shift (up to 4) of the Polar Front (PF) with respect to its present position. Paleoproductivity levels have been con fi rmed as lower than those measured in other sectors of the SouthernOcean, with reduced differences among glacial and interglacial stages. 2011 Elsevier B.V. All rights reserved.
DOI: 10.1016/j.gloplacha.2011.02.008
Subject paleoenvironment
diatom productivity
Southern Ocean
Polar Front

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