• Journal of the Korean earth science society
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• v.21 no.3
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• pp.276-286
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• 2000

A 2.3 m-long core obtained from Marian Cove, King George Island in the South Shetland Islands, West Antarctica shows clues to the glaciomarine sedimentation during the Holocene. The lower part below 115cm-deep of the core is predominated by coarser material such as diamictons compared with the higher part above 105cm dominated by finer material (rhythmite and massive muds). Based on the granulometric features the coarse materials are generally supposed to be glacially-driven and basal tills, whereas the fine materials appear to originate from various sources such as meltwater-supplied, glacially-supplied, wind-blown, and organic origins. However, the presence of erratic coarse particles in the finer materials suggests the ice-rafted origin of the relevant materials. The lower part below 105cm-deep of the core was characterized by lower TN, TC, and TOC contents, and by higher TS and CaCO$_3$ contents compared with its upper part. No significant changes in C/N ratio were shown throughout the core. The ice cliff along the east side of Marian Cove seemed to locate to the west by 1.6km at 8,300 years B. P. on the basis of the repetitive occurrence of rhythmite and diamicton. Since the retreat of ice cliff in 7,970${\pm}$70 years B. P. the sediments of Marian Cove were dominated by fine materials and ice-rafted materials. The abrupt increase of coarse materials in 175cm-4 deep seems to result from supply of coarse materials due to earthquake or other drastic phenomena.

• Ocean and Polar Research
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• v.28 no.1
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• pp.1-12
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• 2006

Analyses of sedimentological and geochemical parameters from two radiocarbon-dated sediment cores (JM98-845-PC and JM98-818-PC) retrieved from the central part of Isfjorden, Svalbard, in the Arctic Sea, reveal detailed paleoclimatic and paleoceanographic histories over the last 15,000 radiocarbon years. The overconsolidated diamicton at the base of core JM98-845-PC is supposed to be a basal till deposited beneath pounding glacier that had advanced during the LGM (Last Glacial Maximum). Deglaciation of the fjord commenced after the glacial maximum, marked by the deposition of interlaminated sand and mud in the ice-proximal zone by subglacial meltwater discharge, and prevailed between 13,700 and 10,800 yr B.P. with enriched-terrigenous organic materials. A return to colder conditions occurred at around 10,800 yr B.P. with a drop in TOC content, which is probably coincident with the Younger Dryas event in the North Atlantic region. At this time, an abrupt decrease of TOC content as well as an increase in C/N ratio suggests enhanced terrigenous input due to the glacial readvance. A climatic optimum is recognized between 8,395 and 2,442 yr B.P., coinciding with 'a mid-Holocene climatic optimum' in Northern Hemisphere sites (e.g., the Laurentide Ice sheet). During this time, as the sea ice receded from the fjord, enhanced primary productivity occurred in open marine conditions, resulting in the deposition of organic-enriched pebbly mud with evidence of TOC maxima and C/N ratio minima in sediments. Fast ice also disappeared from the coast, providing the maximum of IRD (ice-rafted debris) input. Around 2,442 yr B.p. (the onset of Neoglacial), pebbly mud, characterized by a decrease in TOC content, reflects the formation of more extensive sea ice and fast ice, which might cause decreased primary productivity in the surface water, as evidenced by a decrease in TOC content. Our results provide evidence of climatic change on the Svalbard fjords that helps to refine the existence and timing of late Pleistocene and Holocene millennial-scale climatic events in the Northern Hemisphere.