Pleistocene iceberg dynamics on the west Svalbard margin: Evidence from bathymetric and sub-bottom profiler data

QUATERNARY SCIENCE REVIEWS

卷:161

Article

Zhao, Fang¹  Minshull, Timothy A.²  Crocker, Anya J.^2,5  Dowdeswell, Julian A.³  Wu, Shiguo⁴  Soryal, Simon M.² 

[1] Chinese Acad Sci, South China Sea Inst Oceanol, CAS Key Lab Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China

[2] Univ Southampton, Natl Oceanog Ctr Southampton, Ocean & Earth Sci, European Way, Southampton SO14 3ZH, Hants, England

[3] Univ Cambridge, Scott Polar Res Inst, Cambridge CB2 1ER, England

[4] Chinese Acad Sci, Inst Deep Sea Sci & Engn, Sanya 572000, Peoples R China

[5] Univ Sheffield, Dept Anim & Plant Sci, Western Bank, Sheffield S10 2TN, S Yorkshire, England

关键词: Icebergs;    Iceberg ploughmarks;    Western Svalbard margin;    West Spitsbergen Current;    Pleistocene;   

DOI  :  10.1016/j.quascirev.2017.01.019

来源: Elsevier

【 摘 要 】

Large icebergs leave evidence of their drift via ploughing of the seabed, thereby providing a geological record of episodes of calving from thick ice sheets. We interpret large-scale curvilinear depressions on the western Svalbard margin as ploughmarks produced by the keels of icebergs that grounded on the seafloor as they drifted through this area. Iceberg ploughmarks were identified at modern water depths between 300 m and 1000 m and in two distinct stratigraphic units. Combining data from sediment cores with seismic stratigraphy from sub-bottom profiler data suggests that the ploughmarks developed in two phases: (1) during Marine Isotope Stage (MIS) 6; and (2) during MIS 2, indicating the presence of large drifting icebergs on the western Svalbard margin during both the Late Saalian and Late Weichselian glaciations. Sediment-core data along the western Svalbard margin indicate a sharp increase in mass transported sediments dated at 23.7 +/- 0.2 ka, consistent with the MIS 2 age of the younger iceberg ploughed surface. The ploughmarks are oriented in two main directions: SW-NE and S-N. S-N oriented ploughmarks, which shallow to the north, indicate iceberg drift from the south with a SW NE component marking the zone of splitting of the West Spitsbergen Current (WSC) into the Yermak Slope Current (YSC) and North Spitsbergen Current (NSC). Large MIS 6 and MIS 2 icebergs most likely had an Arctic Ocean source. We suggest that these icebergs probably left the Arctic Ocean southward through Fram Strait and circulated within the Norwegian-Greenland Sea before being transported northwards along the Svalbard margin by the WSC. An additional likely source of icebergs to the western Svalbard margin during MIS 2 was the ice-sheet terminating in the western Barents Sea, from which icebergs drifted northward.(C) 2017 Elsevier Ltd. All rights reserved.

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