https://repository.kopri.re.kr/handle/201206/5485 2026-04-07T05:39:56Z https://repository.kopri.re.kr/handle/201206/6589 Title: First Cenozoic glaciers in West Antarctica Authors: Andrzei Gazdzicki; Andrzei Solecki; Krzysztof Birkenmajer; Ho Il Yoon; Andrzej Tatur; Andrzei Przybycin; Krzysztof Krajewski Abstract: One of the most significant global climatic events in the Cenozoic was the transition from greenhouse to icehouse conditions in Antarctica. Tectonic evolution of the region and gradual cooling at the end of Eocene led to the first appearance of ice sheets at the Eocene/Oligocene boundary (ca. 34 Ma). Here we report geological record of mountain glaciers that preceded major ice sheet formation in Antarctica. A terrestrial, valley-type tillite up to 65 metres thick was revealed between two basaltic lava sequences in the Eocene-Oligocene Point Thomas Formation at Herv？ Cove - Breccia Crag in Admiralty Bay, King George Island, South Shetland Islands. K-Ar dating of the lavas suggests the age of the glaciation at 45-41 Ma (Middle Eocene). It is the oldest Cenozoic record of alpine glaciers in West Antarctica, providing insight into the onset of glaciation of the Antarctic Peninsula and South Shetland Islands. 2005-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/5581 Title: Geochemical characteristics and the provenance of sediments in the Bransfield Strait, West Antarctica Authors: Park, Byoung-Kwon; Kim, Yeadong; Jwa, Young-Joo; Lee, Jae Il; Yoo, Kyu-Cheul; Yoon, Ho Il Abstract: The Bransfield Basin is a Quaternary marginal basin separating the South Shetland Islands from the Antarctic Peninsula. We analyzed major, trace, and rare earth element chemistries, and the Nd, Sr, and Pb isotopic compositions for six piston core sediments from the western and eastern Bransfield basins to determine the sediment provenance and factors controlling the composition of the sediments. The Bransfield sediments have chemical characteristics similar to sediments deposited in a tectonically active setting where the source rocks are predominated by igneous rocks of intermediate to mafic composition: low K and high CN in the A-CN-K diagram, low La/Sc, low Th/Sc, and lower LREE/HREE than average shale. The low chemical alteration index of the sediments, about 45 on average, suggests the effect of weathering on the sediment composition was minimal. The source rocks of the Bransfield sediments are mostly composed of Mesozoic to Tertiary arc volcanic and plutonic rocks in the Antarctic Peninsula and the South Shetland Islands. Meanwhile, contributions from other rock types in the northern Antarctic Peninsula region, such as the Trinity Peninsula Group or Scotia Metamorphic Complex, seem to be negligible. The Bransfield sediments can be divided into three distinct compositional groups. Group I sediments have a lower La/Yb and a less prominent negative Eu anomaly than Group II sediments. They are also characterized by negative Ce anomalies. Group I sediments have been derived mainly from the South Shetland Islands, whereas Group II sediments, which are more widespread than Group I sediments in the Bransfield Strait, have been derived mainly from the Antarctic Peninsula. Group III sediments, which are very low in La/Yb with the lowest Sr-87/Sr-86 and the highest Nd-143/Nd-144 values, have been derived from Deception Island. The composition of the Bransfield sediments is largely controlled by the composition of nearby source rocks;the distribution of sediments is further modified by the current and topography of the basin. (c) 2005 Elsevier B.V. All rights reserved. 2005-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/5956 Title: Late Quaternary paleoceanographic change in the South Scotia Sea, northern Antarctic Peninsula. Authors: Yoon, Ho Il; Park, Byoung-Kwon; Kim, Yeadong; OH, JAE KYUNG; Yoo, Kyu-Cheul; Nam, SangHeon Abstract: 최근 남극반도에서 관찰된 온난화 현상과 그에 따른 환경 변화를 예측하기 위해서 과거에 일어났던 단주기 의 기후변화에 대한 정보를 얻는 것은 매우 시급한 일이다. 남극반도 주변에서 일어난 제4기 후기의 고기후 및 고해양 정보를 얻기 위해 남 스코티아 해로부터 얻은 두 개의 중력 코어 퇴적물에 대하여 퇴적상 분석, 퇴적학 및 지화학적 특성 분석 그리고 방사선 탄소연대 자료를 분석한 결과 남 스코티아 해역은 후기 플라이스토세에 서 홀로세 동안 세 차례의 고환경 변화를 겪은 것으로 보인다. Marine Isotope Stage (MIS) 3 (∼22,500 yr B.P.) 동안 남 스코티아 해는 부분적으로 외양(open water) 환경이 조성되었으며, 이 때 해양의 생물생산력의 증가로 인해 퇴적물 내의 총유기탄소량이 다소 증가하였다. 마지막 최대빙하기(22,500∼12,500 yr B.P.) 동안 연구 해 역의 해빙(sea ice) 점유율은 높아졌으며, 그 결과 생물생산력이 줄어들어 퇴적물 내 총유기탄소량이 급격히 감 소하였다. 반면에 웨델 해 기원의 남극 저층수의 영향이 증대되어 육성기원 퇴적물 공급이 활발해졌고, 그 결과 퇴적물 내에 실트엽층이 발달하였다. 최대 빙하기 동안 웨델 해의 폴리냐에서는 일시적으로 생물생산력이 증 가하였으며, 이 때 생성된 심층수에 의해 남 스코티아 해는 일시적으로 유기물 공급을 받았다. 본격적인 해빙 (deglaciation)은 12,500 yr B.P.경부터 시작되었으며 이 때 생물생산력은 점차 증대되어 퇴적물 내 총유기탄소 량이 늘어난 반면에 육성기원 퇴적물의 공급은 줄어들었다. 이 시기에 연구 해역은 일시적으로 단주기의 냉각 기(10,400∼9,500 yr B.P.)를 경험하였으며, 이 때 해빙(sea ice) 점유율이 증가한 결과, 퇴적물 내 총유기탄소량 이 줄어든 반면에 육성기원 물질의 양은 증가하였다. 남 스코티아 해역은 홀로세 중기 온난기(8,300∼2,400 yr B.P.)가 되면서 전형적인 외양(open-water) 환경으로 변하여 해양으로부터 많은 양의 유기물 공급이 있었으며 그 결과 규조연니층을 형성하였다. 남스코티아 해역은 약 2,400 yr B.P.경에 신빙하기(Neoglacial)가 시작되면 서 활발해진 웨델 해 기원의 저층류의 영향을 받아 육성기원 퇴적물의 공급이 다소 증가하였다. 2005-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/5944 Title: Geochemistry of soils of King George Island, South Shetlands,West Antarctica: Implications for pedogenesis in cold regions Authors: Lee, Yong Il; Yoon, Ho Il; Lim, Hyoun Soo Abstract: Fine fractions of soils on the Barton Peninsula, King George Island,West Antarctica have been forming during the last 6000 yr since the last deglaciation. Texturally, they are mostly composed of mineral and rock fragments with some volcanic ashes, which are also indicated by geochemical compositions representing for the nonclay silicate minerals and low values of chemical index of alteration. No significant changes are observed in major- and trace element abundances. Such geochemical characteristics suggest that chemical weathering of bedrocks on the Barton Peninsula seems insignificant and that the soils are composed of physically weathered mineral and rock fragments which are mixed with eolian additions of volcanic ashes and Patagonian dusts. Chondrite-normalized rare earth element (REE) distribution patterns of the Barton Peninsula soils are slightly different from those of bedrocrs, indicating that the REE abundances and characteristics were influenced by eolian additions. Mixing calculations, which mass-balance the REEs, suggest that volcanic ashes blown from Deception Island were the major eolian contributor, followed by atmospheric dusts sourced from Patagonia, South America. Even in the warmer and humid climatic conditions in the maritime Antarctic region, the chemical weathering of bedrocks appears to be insignificant, probably due to the relatively short duration of weathering since the last deglaciation. 2004-01-01T00:00:00Z