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Late Holocene cyclic glaciomarine sedimentation in a subpolar fjord of the South Shetland Islands, Antarctica, and its paleoceanographic significance; sedimentological, geochemical, and paleontological evidence

Ho Il Yoon, Kyu-Cheul Yoo, Young-Suk Bak, Hyoun Soo Lim, Yeadong Kim and Jae Il Lee
Late Holocene cyclic glaciomarine sedimentation in a subpolar fjord of the South Shetland Islands, Antarctica, and its paleoceanographic significance; sedimentological, geochemical, and paleontological evidence
Geological Society of America Bulletin (July 2010) 122 (7-8): 1298-1307

Abstract

The glaciomarine sedimentary record of the fjord head (Collins Harbor) in Maxwell Bay, South Shetland Islands (West Antarctica), a large marine calving embayment, contains repeating couplets of organic-rich massive diamicton and organic-poor stratified diamicton. The massive diamicton is characterized by high total organic carbon (TOC) content and carbon to nitrogen (C/N) ratios and was deposited in a cold climate regime by iceberg-rafted sedimentation from coastal fast ice in which algal plants, as well as gravels, were entrained. The stratified diamicton is characterized by low TOC content and C/N ratios and was formed in a warmer climate regime when the flux of icebergs was suppressed, but turbid meltwater discharge continued to produce lamination. When the meltwater discharge decreased in cold climatic conditions, and resultant phytoplankton productivity was reduced due to the increased sea-ice coverage, ice rafting from shorefast sea ice might have played a major role in entraining benthic algae, as well as loads of sand and gravel, along the coastal area, resulting in an increased C/N ratio and gravel content in the massive diamicton. Accelerator mass spectrometry (AMS) radiocarbon analyses conducted on well-preserved calcite shells were used to construct a chronology for the past 3000 years. Fluctuations in TOC are recorded (approximately four cycles over this time period), with the average duration of a cooling cycle being approximately 500 years. These cycles may be correlative with the high-frequency (550 yr) variability in reduced Circumpolar Deep Water (CDW) on the West Antarctic Peninsula shelf, because a decrease in CDW may be related to reduced deep water production in the North Atlantic during colder periods, as demonstrated for glacial intervals throughout the Pleistocene.


ISSN: 0016-7606
EISSN: 1943-2674
Coden: BUGMAF
Serial Title: Geological Society of America Bulletin
Serial Volume: 122
Serial Issue: 7-8
Title: Late Holocene cyclic glaciomarine sedimentation in a subpolar fjord of the South Shetland Islands, Antarctica, and its paleoceanographic significance; sedimentological, geochemical, and paleontological evidence
Affiliation: Korea Ocean Research and Development Institute, Korea Polar Research Institute, Incheon, South Korea
Pages: 1298-1307
Published: 201007
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 65
Accession Number: 2010-050201
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table, sketch map
S62°12'00" - S62°08'60", W58°52'00" - W58°47'60"
Secondary Affiliation: Kyungpook National University, KOR, South Korea
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201027
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