Constraining the dating of late Quaternary marine sediment records from the Scotia Sea (Southern Ocean) |
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| Institution: | 1. Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meersforschung, Bremerhaven D-27568, Germany;2. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China;3. Fachbereich Geowissenschaften, Universität Bremen, D-28334, Germany;1. British Antarctic Survey, High Cross, Madingley Rd, Cambridge, CB3 0ET, UK;2. University of Nottingham, School of Geography, Nottingham, NG7 2RD, UK;3. British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK;4. Durham University, Department of Geography, South Road, Durham, DH1 3LE, UK;1. State Key Laboratory of Marine Geology, Tongji University, Shanghai, 200092, China;2. University Corporation for Polar Research, Beijing, 100875, China;3. Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH, 43210, USA;4. Department of Geosciences, National Taiwan University, P.O. Box 13-318, 106, Taipei, Taiwan;5. Third Institute of Oceanography, SOA, Xiamen, 361005, China;1. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany;2. MARUM – Zentrum für Marine Umweltwissenschaften der Universität Bremen, Bremen, Germany;1. Dept. Earth Science and Engineering, Imperial College London, UK;2. Grantham Institute – Climate Change and the Environment, Imperial College London, UK;3. Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand;4. Binghamton University, New York, USA;5. Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Japan;6. Instituto Andaluz de Ciencias de la Tierra, CSIC-Universidad de Granada, Spain;7. Dept. of Geology, University of Otago, Dunedin, New Zealand;8. Dept. of Marine Science, University of Otago, Dunedin, New Zealand |
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| Abstract: | In Southern Ocean sediments south of the Antarctic Polar Front, the scarcity of calcareous microfossils hampers the development of sediment chronologies based on radiocarbon dating and oxygen isotope stratigraphy established from carbonate. In this study, radiometric dating, magnetic susceptibility (MS), biogenic opal content, diatom abundance fluctuation, and paleomagnetic information were investigated on a north–south transect of central Scotia Sea sediment cores to verify their reliability as stratigraphic tools in the study area. Radiocarbon dating on organic carbon humic acid fraction can be used to establish the stratigraphy of upper core sections, but regional comparison and correlation are needed to verify a possible bias by fossil carbon contamination. For the long-term stratigraphy, MS, which can be correlated to the Antarctic ice core dust/climate signal, represents the most valuable parameter. Fine-grained single domain magnetite, probably of biogenic origin, makes a significant contribution to the interglacial MS signal, while major contributions from detrital material affect the glacial MS record. The core from the southern Scotia Sea contains significant proportions of biogenic magnetite also in glacial sediments, suggesting depositional environments different from those of the northern Scotia Sea. Our data suggest low contributions of high-coercive minerals to the overall magnetic intensity of glacial and interglacial Scotia Sea sediments, which excludes dust as a main source of the magnetic signal. Opal content can be used to distinguish between cold and warm intervals for the past 300 thousand years. Abundance fluctuation patterns of diatom species Fragilariopsis kerguelensis and Eucampia antarctica are useful stratigraphic tools for periods back to Marine Isotope Stage (MIS) 6. The Mono Lake geomagnetic excursion is identified in Scotia Sea sediments for the first time. Possible correlations of ash layers are suggested between Scotia Sea sediments and East Antarctic ice cores. They have potential to serve as additional age markers for further studies in this area. |
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| Keywords: | Scotia sea Magnetic susceptibility Geomagnetic paleointensity Diatom stratigraphy Tephrochronology |
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