Continental shelf drift deposit indicates non-steady state Antarctic bottom water production in the Holocene

• Published in: Marine Geology
• Main Authors: Harris, PT, Brancolini, G, Armand, LK, Busetti, M, Beaman, RJ, Giorgetti, G, Presti, M, Trincardi, F
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Science BV 2001
• Subjects: Earth Sciences; Geology; Sedimentology; Antarctic; East Antarctica; Antarc*; Antarctica; Sea ice
• Online Access: https://doi.org/10.1016/S0025-3227(01)00183-9; http://ecite.utas.edu.au/22206

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 (yr BP). Slower deposition rates of around 10 cm/kyr, during the past 0-3000 yr and from 5000 to about 13000 yr BP, coincides with the 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. 2001 Elsevier Science B.V. All rights reserved.