https://repository.kopri.re.kr/handle/201206/5543 2026-03-05T07:21:08Z 2026-03-05T07:21:08Z D. Kobayashi S-I Saitoh K. Chikita K. Nagashima N. Harada Y.-H. Park Nam, Seung-il T. Irino M. Yamamoto https://repository.kopri.re.kr/handle/201206/7502 2022-03-24T07:12:49Z 2016-01-01T00:00:00Z

Title: Distribution of detrital minerals and sediment color in western Arctic Ocean and northern Bering Sea sediments: Changes in the provenance of western Arctic Ocean sediments since the last glacial period Authors: D. Kobayashi; S-I Saitoh; K. Chikita; K. Nagashima; N. Harada; Y.-H. Park; Nam, Seung-il; T. Irino; M. Yamamoto Abstract: This paper describes the distribution of detrital minerals and sediment color in the surface sediments of the western Arctic Ocean and the northern Bering Sea and investigates the relationship between mineral composition and sediment provenance. This relationship was used to determine the provenance of western Arctic Ocean sediments deposited during the last glacial period. Sediment color is governed by water depth, diagenesis, and mineral composition. An a*eb* diagram was used to trace color change during diagenesis in the Arctic Ocean sediments. The mineral composition of surface sediments is governed by grain size and provenance. The feldspar/quartz ratio of the sediments studied was higher on the Siberian side than on the North American side of the western Arctic Ocean. The (chlorite þ kaolinite)/ illite and chlorite/illite ratios were high in the Bering Sea but decrease northwards in the Chukchi Sea. Thus, these ratios are useful for provenance studies in the Chukchi Sea area as indices of the Beaufort Gyre circulation and the Bering Strait inflow. The sediments deposited during the last glacial period have a lower feldspar/quartz ratio and a higher dolomite intensity than Holocene sediments on the Chukchi Plateau, suggesting a greater contribution of North American grains during the last glacial period.

2016-01-01T00:00:00Z Hyun, Sangmin Woo, K. S. Nam, Seung-il M. Uchida Yim, Un Hyuk Bahk, J. -J. https://repository.kopri.re.kr/handle/201206/6497 2022-03-24T07:13:59Z 2014-01-01T00:00:00Z

Title: Carbon isotope variations in diploptene for methane hydrate dissociation during the last glacial episode in the Japan Sea/East Sea Authors: Hyun, Sangmin; Woo, K. S.; Nam, Seung-il; M. Uchida; Yim, Un Hyuk; Bahk, J. -J.

2014-01-01T00:00:00Z J. Knies C. Gaina Nam, Seung-il S. Baranwal W. Jokat K. Andreassen J. Matthiessen N. Andersen Ch. Vogt S. De Schepper K. Husum K. Grosfjeld K. Fabian R. Mattingsdal https://repository.kopri.re.kr/handle/201206/6052 2022-03-24T07:11:32Z 2014-01-01T00:00:00Z

Title: Effect of early Pliocene uplift on late Pliocene cooling in the Arctic-Atlantic gateway Authors: J. Knies; C. Gaina; Nam, Seung-il; S. Baranwal; W. Jokat; K. Andreassen; J. Matthiessen; N. Andersen; Ch. Vogt; S. De Schepper; K. Husum; K. Grosfjeld; K. Fabian; R. Mattingsdal Abstract: Despite the undisputed role of the Arctic Ocean in the modern and Pliocene climate system, the Arctic has only recently attracted public awareness that ongoing, fundamental change in the Arctic cryosphere could be a response to global warming. Clarification of the Arctic´s role in global climate during the Pliocene is, however, largely hampered by equivocal stratigraphic constraints. From a well-dated Pliocene sequence from the Yermak Plateau, NW Spitsbergen, we present sedimentological and geochemical data indicating that 4 million years ago terrigenous sediment supply and sources changed abruptly in response to a regional tectonic uplift event. We argue that this event together with contemporary uplift and tilting along the northwestern European continental margin preconditioned the landmasses for glacial ice build-up during intensification of the Northern Hemisphere Glaciation (INHG). Our data further suggest that the final deepening/widening of the Arctic-Atlantic gateway, the Fram Strait, between 6.5 and 5 Ma gradually caused increased deep water mass exchange which, in turn, likely contributed to the intensification of the North Atlantic thermohaline circulation. Coupled to the North Atlantic warm pool as a regional moisture source, declining atmospheric CO2 levels and other feedback mechanisms during the Pliocene, the regional tectonic activities in the high northern latitudes caused decreased summer ablation and thus allowed the initial build-up of glacial ice both in Scandinavia, and the sub-aerially exposed Svalbard/Barents Sea, culminating in the first large scale coastline-shelf edge glaciations at ~2.75 Ma ago.

2014-01-01T00:00:00Z Kim, Sun Young Nam, Seung-il https://repository.kopri.re.kr/handle/201206/6200 2022-03-24T07:11:23Z 2014-01-01T00:00:00Z

Title: Holocene records of paleoclimatic and paleoceanographic changes in the western Arctic Authors: Kim, Sun Young; Nam, Seung-il Abstract: Understanding of past climate variability on millennial to decadal scales is of primary importance in order to assess modern processes and predict future climatic events. Past history of Arctic climate changes is currently receiving increasing attention due to the recent phenomena of rapid sea-ice reduction. In this paper, we thoroughly reviewed the Holocene history of spatio-temporal climatic changes in the western Arctic region in order to better understand recent rapid environmental changes occurring in the Pacific sector of the Arctic, and further to discuss critical issues and new perspectives on the western Arctic in terms of paleoclimate researches. Records of temporal and spatial variations in sea-ice extents as well as marine and terrestrial paleoclimatic proxies show a strong a synchronicity between the western and eastern Arctic throughout the Holocene. The reason for this apparent contradiction across the Arctic may be related to freshwater discharges over the Arctic shelves and the inflow of the Pacific freshwater into the western Arctic Ocean in coupled with a complex interaction between atmospheric and sea-ice dynamics. Special emphasis is placed on a tentative linkage of the late Holocene paleoclimatic events between the Arctic regions and the northwestern Pacific margin, highlighting the notion that climatic events of the northern Pacific Ocean is closely linked to the global climate system through hydrological dynamics in the western Arctic Ocean.

2014-01-01T00:00:00Z