Continental shelf drift deposit indicates non-steady state Antarctic bottom water production in the Holocene
Harris, Peter T, Brancolini, Giuliano, Armand, Leanne, Brusetti, Martina, Beaman, Robin J, Giorgetti, Giovanna, Presti, Massimo, and Trincardi, Fabio (2001) Continental shelf drift deposit indicates non-steady state Antarctic bottom water production in the Holocene. Marine Geology, 179 (1-2). pp. 1-8.
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A late Quaternary, current-lain sediment drift deposit over 30 m in thickness has been discovered on the continental shelf of East Antarctica in an 850 m deep glacial trough off George Vth Land. Radiocarbon dating indicates that a period of rapid deposition on the drift (averaging 290 cm/kyr) occurred in the mid-Holocene, between about 3000 and 5000 yr before present. Slower rates of around 10 cm/kyr, during the past 0-3000 yr and from 5000 to about 13000 yr BP, coincides with deposition of bioturbated, ice-rafted debris (IRD) rich, sandy mud under an energetic bottom current regime. In contrast, the mid-Holocene (3000-5000 yr BP) sediments are fine-grained, laminated to cross-laminated with minimal IRD content, and are contemporaneous with a period of warmer marine conditions with less sea ice production. This pattern suggests that bottom currents were weaker than present day in the mid-Holocene, and that the rate of dense bottom water production was reduced at that time. This scenario is consistent with the hypothesis of non-steady state rates of Antarctic bottom water production through the Holocene as recently proposed by Broecker and his colleagues.
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|Keywords:||Antarctica, Continental shelf, Sediment drift, Ripple cross-lamination, Bottom water, Ocean circulation|
|FoR Codes:||04 EARTH SCIENCES > 0405 Oceanography > 040503 Physical Oceanography @ 0%|
04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 0%
|Deposited On:||03 Nov 2006|
|Last Modified:||14 Feb 2011 00:50|
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