Biogenic-silica accumulation in the Ross Sea and the importance of Antarctic continental-shelf deposits in the marine silica budget |
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| Institution: | 1. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, ul. Favorskogo 1a, Irkutsk, 664033, Russia;2. Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Bdg. A43, Telegrafenberg, Potsdam, 14473, Germany;3. Institute of Geological Sciences, Freie Universitaet Berlin, Bdg. D, Malteserstrasse 74-100, 12249, Germany;4. Institute of Archeology and Ethnography, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Lavrentieva 17, Novosibirsk, 630090, Russia |
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| Abstract: | Thirty-five box cores were collected from the continental shelf in the Ross Sea during cruises in January and February, 1983. Pb-210 and Pu-239, 240 geochronologies coupled with biogenic-silica measurements were used to calculate accumulation rates of biogenic silica. Sediment in the southern Ross Sea accumulates at rates ranging from ≤0.6 to 2.7 mm/y, with the highest values occurring in the southwestern Ross Sea. Biogenic-silica content in surface sediments ranges from 2% (by weight) in Sulzberger Bay and the eastern Ross Sea to 41% in the southwestern Ross Sea. Biogenic-silica accumulation in the southwestern Ross Sea averages 2.7 × 10−2 g/cm2/y and is comparable to accumulation rates in high-productivity, upwelling environments from low-latitude continental margins (e.g., Gulf of California, coast of Peru). The total rate of biogenic-silica accumulation in the southern Ross Sea is approximately 0.2 × 1014 g/y, with most of the accumulation occurring in basins (500–1000 m water depth). If biogenic-silica accumulation in the southern Ross Sea continental shelf is typical of other basins on the Antarctic continental shelf, as much as 1.2 × 1014 g/y of silica could be accumulating in these deposits. Biogenic-silica accumulation on the Antarctic continental shelf may account for as much as a fourth of the dissolved silica supplied to the world ocean by rivers and hydrothermal vents. |
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