Southern Ocean bioproductivity during the last glacial cycle – new detection method and decadal-scale insight from the Scotia Sea
Published:January 01, 2013
D. Sprenk, M. E. Weber, G. Kuhn, P. Rosén, M. Frank, M. Molina-Kescher, V. Liebetrau, H.-G. Röhling, 2013. "Southern Ocean bioproductivity during the last glacial cycle – new detection method and decadal-scale insight from the Scotia Sea", Antarctic Palaeoenvironments and Earth-Surface Processes, M. J. Hambrey, P. F. Barker, P. J. Barrett, V. Bowman, B. Davies, J. L. Smellie, M. Tranter
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We present biogenic opal flux records from two deep-sea sites in the Scotia Sea (MD07-3133 and MD07-3134) at decadal-scale resolution, covering the last glacial cycle. In addition to conventional and time-consuming biogenic opal measuring methods, we introduce new biogenic opal estimation methods derived from sediment colour b*, wet bulk density, Si/Ti-count ratio and Fourier transform infrared spectroscopy (FTIRS). All methods capture the biogenic opal amplitude; however, FTIRS–a novel method for marine sediment – yields the most reliable results. 230Th normalization data show strong differences in sediment focusing with intensified sediment focusing during glacial times. At MD07-3134 230Th normalized biogenic opal fluxes vary between 0.2 and 2.5 g cm−2 kyr−1. Our biogenic opal flux records indicate bioproductivity changes in the Southern Ocean, strongly influenced by sea ice distribution and also summer sea surface temperature changes. South of the Antarctic Polar Front, lowest bioproductivity occurred during the Last Glacial Maximum when upwelling of mid-depth water was reduced and sea ice cover intensified. Around 17 ka, bioproductivity increased abruptly, corresponding to rising atmospheric CO2 and decreasing seasonal sea ice coverage.
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Antarctic Palaeoenvironments and Earth-Surface Processes
The volume highlights developments in our understanding of the palaeogeographical, palaeobiological, palaeoclimatic and cryospheric evolution of Antarctica. It focuses on the sedimentary record from the Devonian to the Quaternary Period. It features tectonic evolution and stratigraphy, as well as processes taking place adjacent to, beneath and beyond the ice-sheet margin, including the continental shelf.
The contributions in this volume include several invited review papers, as well as original research papers arising from the International Symposium on Antarctic Earth Sciences in Edinburgh, in July 2011. These papers demonstrate a remarkable diversity of Earth science interests in the Antarctic. Following international trends, there is particular emphasis on the Cenozoic Era, reflecting the increasing emphasis on the documentation and understanding of the past record of ice-sheet fluctuations. Furthermore, Antarctic Earth history is providing us with important information about potential future trends, as the impact of global warming is increasingly felt on the continent and its ocean.