https://repository.kopri.re.kr/handle/201206/15766 Wed, 08 Apr 2026 16:12:20 GMT 2026-04-08T16:12:20Z https://repository.kopri.re.kr/handle/201206/16461 Title: Synchronous mid-Holocene marine and terrestrial deglaciation in the Ross Sea, Antarctica Authors: Parker Rebecca L.; Riesselman Christina R.; Truax Olivia J.; Jones Richard S.; Lee, Jae Il; Lee, Min Kyung; Jacobsen Geraldine; Rosenheim Brad E.; Subt Cristina; Zawadzki Atun; Ginnane Catherine; Naeher Sebastian; Dunbar Gavin; McKay Robert M.; Levy Richard; Turnbull Jocelyn; Yoo, Kyu-Cheul Abstract: The Ross Ice Shelf buttresses ice draining from both East and West Antarctica and its collapse could accelerate the loss of inland ice sheets, rapidly raising sea level. Documenting the location, timing and rate of past glacial retreat can help reveal processes driving rapid mass loss, informing projections of ice sheet responses to a warming climate. Here, we present a record of mid-Holocene ice retreat from the southwestern Ross Sea using facies succession and paired ramped pyrolysis oxidation C-14/Pb-210 chronology. This record shows rapid ice shelf retreat from 6.9-5.4 cal kyr BP, coeval with thinning of adjacent outlet glaciers. Our findings reconcile earlier discrepancies in terrestrial and marine reconstructions, and indicate that synchronous grounding line retreat from west of Ross Island to the Siple Coast at similar to 7-6.2 cal kyr BP was likely driven by warm-water incursions, a process active in parts of Antarctica today. Mon, 01 Dec 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16461 2025-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16601 Title: Increased Sea Ice Duration in Moubray Bay, Northwest Ross Sea Linked to Early Holocene Wind Strength Authors: Gilmer Greer; Riesselman Christina R.; Kim, Sunghan; Yoo, Kyu-Cheul; Lee, Jae Il; Lee, Min Kyung; Ginnane Catherine E.; Rosenheim Brad E.; Turnbull Jocelyn; Parker Rebecca; Jacobsen Geraldine; Mckay Robert; Levy Richard; Moy Christopher M. Abstract: Sea ice in the Ross Sea plays a critical role in the formation of dense water masses, ice sheet stability, and air-sea gas exchange, and also supports unique ecosystems. However, its seasonal and spatial variability makes it challenging to include in model simulations. To address this, new sea ice records that extend beyond the satellite era and include periods of climate change are essential. This new sediment record from Moubray Bay, northwest Ross Sea, reconstructs environmental conditions between similar to 11,300 and similar to 10,900 cal yr BP-a time of rapid retreat of marine-based ice sheets and coastal glaciers in the region. The diatom assemblage is dominated by three taxa: Fragilariopsis curta, Corethron pennatum, and Chaetoceros resting spores. Variations in their relative abundances reveal changes in wind strength, water column structure, and sea ice concentration and duration. Between similar to 11,300 and similar to 11,200 cal yr BP, environmental conditions are characterized by a stabilized water column due to fresh meltwater influx, and weaker winds, which resulted in shorter sea ice duration and reduced winter sea ice concentration. This continued after similar to 11,200 cal yr BP but stronger winds linked to deepening of Amundsen Sea Low-like circulation triggered short-term water column stratification. Sea ice concentration and duration increased after similar to 11,100 cal yr BP driven by cooling of the sea surface by stronger southerly winds. Concurrent changes in early Holocene marine and terrestrial climate records from the Ross Sea indicate a shift in atmospheric circulation during the early Holocene. Mon, 01 Dec 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16601 2025-12-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16592 Title: Mid-to-late Pleistocene Depositional Environments at the Ross Sea Continental margin: Implications for Antarctic Ice Sheet Dynamics Authors: Chinmay Dash; Seong, Yeong Bae; Ajay Kumar Singh; Lee, Min Kyung; Lee, Jae Il; Yoo, Kyu-Cheul; Rhee, Hyun Hee; Yu, Byung Yong Abstract: This study investigates a sediment core (RS15-LC47) from the Ross Sea continental rise to reconstruct ice sheet dynamics and paleodepositional environments over the past 800 ka. We employed a multi-proxy approach in this study, integrating whole-core magnetic susceptibility (MS), total organic carbon (TOC), calcium carbonate (CaCO₃), biogenic silica, sedimentological features, and the isotopic ratio of authigenic beryllium ((10Be/9Be)reac). The interval between 750 and 550 ka represents an intensified glacial phase characterized by expanded ice sheets, strengthened bottom currents, and reduced marine productivity. The dominance of contourite deposits interspersed with slumped sediments suggests that the sediment deposition occurred under highly dynamic and unstable conditions driven by intensified bottom currents. The presence of poorly sorted sediments and millimetre-scale faults further indicates gravity flow deposition, likely triggered by ice-sheet advances. Low (10Be/9Be)reac ratios in this interval suggest limited scavenging in open marine settings, likely due to reduced sediment transit time to the coring site as advancing ice sheets extended toward the shelf edge. Although TOC values are highest in this interval, a high total organic carbon/nitrogen (TOC/TN) ratio and low excess Barium (Baex) suggest increased terrestrial input from the advancing ice sheets and a reduced marine productivity under intense glacial conditions in the Ross Sea. Following the Mid-Pleistocene Transition (MPT), between 550 and 250 ka, MS values remained consistently low, while (10Be/9Be)reac ratios were notably elevated, indicating relatively warmer conditions with diminished glacial influence. The TOC/TN ratios during this interval resemble those observed in the euphotic layer of the Ross Sea, with relatively higher Baex and TOC suggesting enhanced marine productivity under relatively warmer conditions between 550 and 250 ka. During the late Pleistocene (>250 ka), the depositional environment became increasingly influenced by glacial-interglacial cycles, with warmer interglacials driving enhanced productivity. During this interval, coarser grain sizes point to stronger bottom currents, while the sharp rise in (10Be/9Be)reac ratios indicates interglacial conditions associated with ice sheet retreat. The longer sediment transit from the subglacial zone to the depositional site during these warmer periods enhanced scavenging of Be isotopes in open marine settings, resulting in elevated (10Be/9Be)reac values. A positive correlation between OpalMAR, TOC%, and (10Be/9Be)reac during interglacials reflects a direct link between increased marine productivity and warmer climatic phases. Our findings emphasize how ice-sheet expansion and retreat control the depositional processes in the region. Wed, 01 Oct 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16592 2025-10-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/16086 Title: Recording of paleoenvironmental changes using diatom assemblages from the Amundsen Sea, Antarctica Authors: Bak, Young-Suk; Kim, Sunghan; Yoo, Kyu-Cheul; Lee, Jae Il; Lee, Min Kyung; Ha, Sangbeom Abstract: To reconstruct past ice shelf behavior, diatoms were analyzed from core sediments obtained near the Getz ‘A’ Ice Shelf in the Amundsen Sea embayment of Antarctica. A total of 50 diatom species representing 22 genera were identified from AM22-GC10B, with abundances varying from 0.5 to 8.3×107/g. By examining the patterns of sea ice, open ocean species, and magnetic susceptibility (MS) values, three assemblage zones were established. These zones reveal significant changes in the paleoenvironment: Diatom assemblage zone I corresponds to subglacial condition, characterized by low diatoms and high magnetic susceptibility values. Diatom assemblage zone II represents the glacialmarine, showing a shift from subglacial to seasonal open marine conditions, with increasing diatom abundance and decreasing magnetic susceptibility. Diatom assemblage zone III indicates a seasonal open marine period, characterized by high diatom abundance, increasing Chaetoceros resting spores, decreasing sea ice species, and increasing open ocean species.; 남극 아문젠해 만내 Getz ‘A’ Ice Shelf 인근에서 획득한 AM22-GC10B로부터 과거 빙붕의 분포 변화를 알아보기 위해 규조를 분석하였다. 총 22속 50종의 규조가 동정되었으며, 규조 개체수 농도는 0.5～8.3×107/g의 범위에 해당하였다. 규조 군집의 해빙종과 공해종의 분포 양상, 대자율값을 분석하여 총 3개의 군집대를 설정하였고, 이는 과거 환경 변화를 뚜렷하게 보여준다. 군집대I 은 규조 산출이 거의 없고 대자율 값이 높게 나타나는 특징을 보이며, 이는 빙하하부에서 형성된 환경을 지시한다. 군집대 II는 규조류 개체수가 증가하고 대자율 값이 감소하는 경향을 나타내며, 이는 빙하하부 환경에서 벗어나 계절적으로 해빙이 없는 해양 환경으로 전이되는 빙해양 환경을 지시한다. 군집대 III에서는 개체수와 휴면포자(Chaetoceros resting spores)의 수가 뚜렷하게 증가하고 해빙종의 산출이 감소하는 반면 공해종의 산출이 증가하는 양상을 보이는 것은 계절적으로 해빙이 사라진 환경에서 퇴적된것으로 해석된다. Mon, 01 Sep 2025 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/16086 2025-09-01T00:00:00Z