https://repository.kopri.re.kr/handle/201206/11922 Sun, 05 Apr 2026 23:05:47 GMT 2026-04-05T23:05:47Z https://repository.kopri.re.kr/handle/201206/13702 Title: Spatial variations of authigenic beryllium isotopes in surface sediments of the Antarctic oceans: a proxy for sea ice dynamics and sedimentary environments Authors: Rhee, Hyun Hee; Seong, Yeong Bae; Lee, Min Kyung; Jeong, Ara; Dash, Chinmay; Lee, Jae Il; Yoo, Kyu-Cheul; Yu, Byung Yong Abstract: This study documents spatial variations in authigenic Be-9 and Be-10 concentrations and Be-10/Be-9 ratios in different glacial settings in the Weddell and Ross seas, Antarctica. Weddell Sea surface sediments have the lowest Be-10 and highest Be-9 concentrations, and most depleted Be-10/Be-9 ratios, as compared with other regions, indicating Be-9 enrichment from the recently collapsed Larsen Ice Shelf (LIS) B and reduction of Be-10 supply due to blockage by the un-deglaciated LIS C. Local Be-10 deposition varies across the open marine Ross Sea, which is more affected by seasonal sea ice persistence than ocean currents. Higher Be-10/Be-9 ratios in the western Ross Sea and higher Be-10 concentrations in the eastern Ross Sea correlate with higher sea ice concentrations and changes, and vice versa in the central Ross Sea. The higher sea ice concentration not only blocks atmospheric Be-10 and dust deposition during the frozen season, but increases the dust flux and supply of Be isotopes during the sea ice melting season. Thus, the spatial distribution of Be isotopes in surface sediments of the Antarctic oceans can be used as a proxy for sea ice dynamics and sedimentary environments. Mon, 01 Aug 2022 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/13702 2022-08-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/13625 Title: Quaternary ice thinning of David Glacier in the Terra Nova Bay region, Antarctica Authors: Rhee, Hyun Hee; Lee, Min Kyung; Seong, Yeong Bae; Lee, Jae Il.; Yoo, Kyu-Cheul; Stutz, Jamey; Yu, Byung Yong Abstract: Understanding the history of Antarctic glaciation is important for interpreting paleoclimatic changes and estimating the changes in climate, sea level, and ice volume in the future. Ice core studies of the East Antarctic Ice Sheet (EAIS) and marine sediment cores from the entire Ross Sea have employed numerous proxies to reconstruct the glacial history of the Antarctic region. However, the ice and marine core records can be biased because of their specific locations, such as the uppermost accumulation zone or the terminus of the ablation zone, thereby introducing significant uncertainties in ice modeling. In this study, we analyzed 34 new Be-10 and Al-26 samples from four benches that were glaciated in the past by David glacier and incorporate the present ice-free flat surfaces. We suggest that the David glacier experienced monotonic and stepwise vertical lowering along the flanks of Mt. Priestley since the early Pleistocene. The uppermost bedrock benches on Mt. Priestley were exposed at 1.77 +/- 0.32 Ma, with no evidence of subsequent overriding by readvancing ice. At Mt. Priestley, the David glacier has been characterized by a cold-based regime since 1.77 Ma, with a denudation rate of only similar to 16 cm/Ma, corresponding to the regional transition from warm to cold-based glaciation at 3.5 Ma. Simple exposure ages from two lower benches date to Marine Isotope Stage (MIS) 7 (234.1 +/- 13.1 ka; 545 m asl) and MIS 4 (64.8 +/- 13.7 ka; 222 m asl), suggesting that, since MIS 8, the overall lowering of glaciers has remained monotonic. The upper bench marks the lower limit of the MIS 8 glacial period and the upper limit of Penultimate Glacial Maximum (MIS 6), while the lower landform defines the upper limit of the last glacial period (MIS 4-2). The magnitude of Quaternary ice thinning at the David glacier was the highest (similar to 990 m) in the present terminal area (i.e., the most sensitive ablation zone), in contrast to the other outlet glaciers draining into the Terra Nova Bay, which experienced less ice lowering. The combination of the terrestrial (in situ Be-10 and Al-26) and previous marine (authigenic Be-10) cosmogenic data used in our study document the history of lowering of the David glacier driven by climatic changes during the Pleistocene. Both deglaciation and glaciation were limited during the mid-Pleistocene transition (MPT) and prior to the mid-Bruhnes event (MBE), due to the prevailing cold and arid climate, whereas deglaciation was dominant during other warm periods. Tue, 01 Feb 2022 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/13625 2022-02-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/14067 Title: Quaternary ice thinning of David Glacier in the Terra Nova Bay region, Antarctica Authors: Rhee, Hyun Hee; Lee, Min Kyung; Seong, Yeong Bae; Lee, Jae Il; Yoo, Kyu-Cheul; Stutz, Jamey; Yu, Byung Yong Abstract: Understanding the history of Antarctic glaciation is important for interpreting paleoclimatic changes and estimating the changes in climate, sea level, and ice volume in the future. Ice core studies of the East Antarctic Ice Sheet (EAIS) and marine sediment cores from the entire Ross Sea have employed numerous proxies to reconstruct the glacial history of the Antarctic region. However, the ice and marine core records can be biased because of their specific locations, such as the uppermost accumulation zone or the terminus of the ablation zone, thereby introducing significant uncertainties in ice modeling. In this study, we analyzed 34 new 10Be and 26Al samples from four benches that were glaciated in the past by David glacier and incorporate the present ice-free flat surfaces. We suggest that the David glacier experienced monotonic and stepwise vertical lowering along the flanks of Mt. Priestley since the early Pleistocene. The uppermost bedrock benches on Mt. Priestley were exposed at 1.77 ± 0.32 Ma, with no evidence of subsequent overriding by readvancing ice. At Mt. Priestley, the David glacier has been characterized by a cold-based regime since 1.77 Ma, with a denudation rate of only ~16 cm/Ma, corresponding to the regional transition from warm to cold-based glaciation at 3.5 Ma. Simple exposure ages from two lower benches date to Marine Isotope Stage (MIS) 7 (234.1 ± 13.1 ka; 545 m asl) and MIS 4 (64.8 ± 13.7 ka; 222 m asl), suggesting that, since MIS 8, the overall lowering of glaciers has remained monotonic. The upper bench marks the lower limit of the MIS 8 glacial period and the upper limit of Penultimate Glacial Maximum (MIS 6), while the lower landform defines the upper limit of the last glacial period (MIS 4-2). The magnitude of Quaternary ice thinning at the David glacier was the highest (~990 m) in the present terminal area (i.e., the most sensitive ablation zone), in contrast to the other outlet glaciers draining into the Terra Nova Bay, which experienced less ice lowering. The combination of the terrestrial (in situ 10Be and 26Al) and previous marine (authigenic 10Be) cosmogenic data used in our study document the history of lowering of the David glacier driven by climatic changes during the Pleistocene. Both deglaciation and glaciation were limited during the mid-Pleistocene transition (MPT) and prior to the mid-Bruhnes event (MBE), due to the prevailing cold and arid climate, whereas deglaciation was dominant during other warm periods. Tue, 01 Feb 2022 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/14067 2022-02-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/13574 Title: 10Be and 10Be/9Be in glaciomarine sediments of Ross Sea, Antarctica: implications for mid-late Quaternary paleoenvironmental changes Authors: Dash, Chinmay; Lee, Min Kyung; Seong, Yeong Bae; Rhee, Hyun He; Lee, Jae Il; Yoo, Kyu-Cheul Abstract: This study documents the variation of Be isotopes (10Be and 9Be) and their ratio (10Be/9Be) from a Ross Sea sediment core (LC42) with relation to mid to late Pleistocene geomagnetic and paleoclimatic changes. Significant changes in Be isotope concentration are observed during pre and post-Mid-Pleistocene Transition (MPT) periods. The 10Be concentration and 10Be/9Be ratio show a gradual decrease during the late Matuyama Chron, suggesting a relative increase in geomagnetic intensity. The overproduction episode associated with the Matuyama-Brunhes Boundary (MBB) does not show any pre- MBB precursor event. The progressively decreasing trend observed in 10Be and 10Be/9Be ratio records from 1 to 0.8 Ma, with minimum values at around 0.8 Ma, suggests a relatively open sea condition during the early part of MPT and an extended glacial condition around MIS 22. The 10Be and 10Be/9Be ratios are approximately constant during the pre-Mid Bruhnes Event (MBE) period and show a gradual increase after the MBE, indicating a climatic transition from colder (pre-MBE) to relatively warmer (post-MBE) conditions. Fri, 01 Oct 2021 00:00:00 GMT https://repository.kopri.re.kr/handle/201206/13574 2021-10-01T00:00:00Z