DSpace Collection:https://repository.kopri.re.kr/handle/201206/51732026-04-06T04:42:58Z2026-04-06T04:42:58ZSedimentological, geochemical and palaeontological evidence for a neoglacial cold event during the late Holocene in the continental shelf of the northern South Shetland Islands, West AntarcticaYoo, Kyu-CheulKeun, Khim BooKim, Jin-KyungYoon, Ho Ilhttps://repository.kopri.re.kr/handle/201206/60112022-03-24T07:11:17Z2009-01-01T00:00:00ZTitle: Sedimentological, geochemical and palaeontological evidence for a neoglacial cold event during the late Holocene in the continental shelf of the northern South Shetland Islands, West Antarctica
Authors: Yoo, Kyu-Cheul; Keun, Khim Boo; Kim, Jin-Kyung; Yoon, Ho Il
Abstract: Two sediment cores obtained from the continental shelf of the northern South Shetland Islands, West Antarctica, consist of: an upper unit of silty mud, bioturbated by a sluggish current, and a lower unit of well-sorted, laminated silty mud, attributed to an intensified Polar Slope Current. Geochemical and accelerator mass spectrometry 14C analyses yielded evidence for a late Holocene increase in sea-ice extent and a decrease in phytoplankton productivity, inferred from a reduction in the total organic carbon content and higher C : N ratios, at approximately 330 years B.P., corresponding to the Little Ice Age. Prior to this, the shelf experienced warmer marine conditions, with greater phytoplankton productivity, inferred from a higher organic carbon content and C : N ratios in the lower unit. The reduced abundance of Weddell Sea ice-edge bloom species (Chaetoceros resting spores, Fragilariopsis curta and Fragilariopsis cylindrus) and stratified cold-water species (Rhizosolenia antennata) in the upper unit was largely caused by the colder climate. During the cold period, the glacial restriction between theWeddell Sea and the shelf of the northern South Shetland Islands apparently hindered the influx of ice-edge bloom species from the Weddell Sea into the core site. The relative increases in the abundance of Actinocyclus actinochilus and Navicula glaciei, indigenous to the coastal zone of the South Shetland Islands, probably reflects a reduction in the dilution of native species, resulting from the diminished influx of the ice-edge species from the Weddell Sea. We also document the recent reduction of sea-ice cover in the study area in response to recent warming along the Antarctic Peninsula.2009-01-01T00:00:00ZCarbon and nitrogen isotope composition of vegetation on King George Island, maritime AntarcticaLee, Yong IlYoon, Ho IlLim, Hyoun Soohttps://repository.kopri.re.kr/handle/201206/61452022-03-24T07:11:34Z2009-01-01T00:00:00ZTitle: Carbon and nitrogen isotope composition of vegetation on King George Island, maritime Antarctica
Authors: Lee, Yong Il; Yoon, Ho Il; Lim, Hyoun Soo
Abstract: We report abundance of 13C and 15N contents in terrestrial plants (mosses, lichens, liverworts, algae and grasses) from the area of Barton Peninsula (King George Island, maritime Antarctic). The investigated plants show a wide range of d13C and d15N values between -29.0 and -20.0% and between -15.3 and 22.8%, respectively. The King George Island terrestrial plants show species specificity of both carbon and nitrogen isotope compositions, probably due to differences in plant physiology and biochemistry, related to their sources and in part to water availability. Carbon isotope compositions of Antarctic terrestrial plants are typical of the C3 photosynthetic pathway. Lichens are characterized by the widest carbon isotope range, from -29.0 to -20.0%. However, the average d13C value of lichens is the highest (-23.6 ± 2.8%) among King George Island plants, followed by grasses (-25.6 ± 1.7%), mosses (-25.9 ± 1.6%), liverworts (-26.3 ± 0.5%) and algae (-26.3 ± 1.2%), partly related to habitats controlled by water availability. The d15N values of moss samples range widest (-9.0 to 22.8%, with an average of 4.6 ± 6.6%). Lichens are on the average most depleted in 15N (mean = -7.4 ± 6.4%), whereas algae are most enriched in 15N (10.0 ± 3.3%). The broad range of nitrogen isotope compositions suggest that the N source for these Antarctic terrestrial plants is spatially much variable, with the local presence of seabird colonies being particularly significant.2009-01-01T00:00:00ZRate of late Quaternary ice-cap thinning on King George Island, South Shetland Islands, West Antarctica definded by cosmogenic 36Cl surface exposure datingSeong, Y.B.L.A. OwenLee, Yong IlM.W. CaffeeKim, YeadongYoon, Ho IlLim, Hyoun Soohttps://repository.kopri.re.kr/handle/201206/60202022-03-24T07:12:27Z2009-01-01T00:00:00ZTitle: Rate of late Quaternary ice-cap thinning on King George Island, South Shetland Islands, West Antarctica definded by cosmogenic 36Cl surface exposure dating
Authors: Seong, Y.B.; L.A. Owen; Lee, Yong Il; M.W. Caffee; Kim, Yeadong; Yoon, Ho Il; Lim, Hyoun Soo
Abstract: Glacial landforms on the Barton and Weaver peninsulas of King George Island in the South Shetland Islands, West Antarctica were mapped and dated using terrestrial cosmogenic 36Cl methods to provide the first quantitative terrestrial record for late Quaternary deglaciation in the South Shetland Islands. 36Cl ages on glacially eroded and striated bedrock surfaces range from 15.5+2.5 kyr to 1.0+0.7 kyr. The 36Cl ages are younger with decreasing altitude, indicating progressive downwasting of the southwestern part of the Collins Ice Cap at a rate of -12mm/yr since 15.5+2.5 kyr ago, supporting the previously published marine records for the timing and estimate of the rate of deglaciation in this region.2009-01-01T00:00:00ZIntroduction of single grain OSL dating technique: sorted circle of Svalbard and archaeological site of FranceMailys Mailliez최정헌홍성찬김종욱Yoon, Ho IlLim, HyounsooLee, Jae Ilhttps://repository.kopri.re.kr/handle/201206/79232022-03-24T07:12:15Z2009-01-01T00:00:00ZTitle: Introduction of single grain OSL dating technique: sorted circle of Svalbard and archaeological site of France
Authors: Mailys Mailliez; 최정헌; 홍성찬; 김종욱; Yoon, Ho Il; Lim, Hyounsoo; Lee, Jae Il
Abstract: OSL(Optically Stimulated Luminescence; 이하 OSL) 연대측정법은 1980년대 중반 빛에너지로 인해 광물입자에서 방출되는 루미네선스 신호(Optically Stimulated Luminescence; 이하 OSL)가 대상광물이 흡수한 이온화방사선량(ionising radiation)과 비례한다는 관찰을 바탕으로 그 기본이론이 정립되었고(Huntely et al., 1985), 1990년대를 거치면서 좀 더 정밀하고 정확한 OSL 연대측정 결과, 특히 신뢰도 높은 등가선량(equivalent dose)값을 도출하기 위한 여러 실험적·이론적 노력들이 진행되어왔다(예: Mejdahl and Bøtter-Jensen, 1994; Galloway, 1996; Murray et al., 1997). 이후, 2000년대에 접어들면서 단일시료재현법(Single-Aliquot Regenerative-Dose protocol; SAR법, Murray and Wintle, 2000)의 개발과 더불어, OSL 연대측정법은 지형학, 고고학, 고기후학 등 제4기 퇴적층의 연대결과를 필요로 하는 학문분야에 폭넓게 적용되고 있다(Lian and Roberts, 2006). 하지만, 대상퇴적층이 퇴적당시 햇빛에 충분한 시간동안 노출되지 못하여 기존의 OSL 신호를 가지고 퇴적되었거나(heterogeneous bleaching 혹은 homogeneous incomplete bleaching), 퇴적이후 교란작용(생교란 혹은 지진활동에 수반된 교란작용)이 있었을 경우, 퇴적층내에는 다양한 퇴적연대를 지시하는 광물입자들(특히, OSL 연대측정 대상광물인 석영이나 장석입자)이 혼재되어 있을 가능성이 있어, 각 개별입자의 특성에 가장 적합한 등가선량측정법을 적용한다고 하여도 정확한 퇴적시기를 지시하는 OSL 연대를 구하는 데에 한계가 있다. 특히, 수 천개의 석영입자에서 한꺼번에 방출되는 OSL신호를 사용하는 다입자 OSL연대측정법(multiple grain OSL dating)으로는 짧은 햇빛노출시간 및 퇴적후 교란작용에 의한 OSL연대측정 오차를 극복하고 정확한 퇴적시기를 추정하는 작업은 불가능하다. 반면, 최근 녹색레이져를 사용하여 각 개별입자로부터 방출되는 OSL 신호를 측정할 수 있는 장비가 개발되어(Bøtter-Jensen et al., 2002), 동일 퇴적층내에 다양한 퇴적시기를 지시하는 석영입자들이 혼재한다 하더라도, 이들 중 대상 퇴적물의 퇴적시기를 지시하는 입자들만 선택적으로 사용한 OSL 연대측정이 가능하게 되었다(Single Grain OSL dating, 예: Demuro et al., 2008). 이번 발표에서는 노르웨이 스발바드섬의 원형구조토와 서부프랑스지역 하성2009-01-01T00:00:00Z