https://repository.kopri.re.kr/handle/201206/11568 2026-04-05T18:08:46Z https://repository.kopri.re.kr/handle/201206/13011 Title: A Pulse of Meteoric Subsurface Fluid Discharging Into the Chukchi Sea During the Early Holocene Thermal Maximum (EHTM) Authors: Kim, Ji-Hoon; Hong, Wei-Li; Torres, Marta E.; Ryu, Jong-Sik; Kang, Moo-Hee; Han, Dukki; Nam, Seung-il; Hur, Jin; Koh, Dong-Chan; Niessen, Frank; Lee, Dong-Hun; Jang, Kwangchul; Rae, James William Buchanan; Chen, Meilian Abstract: The response of Arctic Ocean biogeochemistry to subsurface flow driven by permafrost thaw is poorly understood. We present dissolved chloride and water isotopic data from the Chukchi Sea Shelf sediments that reveal the presence of a meteoric subsurface flow nriched in cations with a radiogenic Sr fingerprint. This subsurface fluid is also enriched in dissolved inorganic carbon and methane that bear isotopic compositions indicative of a carbon reservoir modified by reactions in a closed system. Such fluid characteristics are in stark contrast with those from other sites in the Chukchi Sea where the pore water composition shows no sign of meteoric input, but reflect typical biogeochemical reactions associated with early diagenetic sequences in marine sediment. The most likely source of the observed subsurface flow at the Chukchi Sea Shelf is from the degradation of permafrost that had extended to the shelf region during the Last Glacial Maximum. Our data suggest that the permafrostdriven subsurface flow most likely took place during the 2？3°C warming in the Early Holocene Thermal Maximum. This time scale is supported by numerical simulation of pore water profiles, which indicate that a minimum of several thousand years must have passed since the cessation of the subsurface methane-bearing fluid flow. 2021-08-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/13065 Title: Seismostratigraphic and Geomorphic Evidence for the Glacial History of the Northwestern Chukchi Margin, Arctic Ocean Authors: Kim, Sookwan; Polyak, Leonid; Joe, Young Jin; Niessen, Frank; Kim, Hyoung Jun; Choi, Yeonjin; Kang, Seung-Goo; Hong, Jong Kuk; Nam, Seung-il; Jin, Young Keun Abstract: High-resolution seafloor mapping provides insights into the dynamics of past ice-sheets/ice-shelves on high-latitude continental margins. Geological/geophysical studies in the Arctic Ocean suggest widespread Pleistocene ice grounding on the Chukchi？East Siberian continental margin. However, flow directions, timing, and behavior of these ice masses are not yet clear due to insufficient data. We present a combined seismostratigraphic and morphobathymetric analysis of the Chukchi Rise off the northwestern Chukchi margin using the densely acquired sub-bottom profiler (SBP) and multibeam echosounder (MBES) data. Comparison with deeper airgun seismic records shows that the SBP data cover most of the glaciogenic stratigraphy possibly spanning ca. 0.5？1 Ma. Based on the stratigraphic distribution and geometry of acoustically transparent glaciogenic diamictons, the lateral and vertical extent of southern-sourced grounded ice became smaller over time. The older deposits are abundant as debris lobes on the slope contributing to a large trough mouth fan, whereas younger grounding-zone wedges are found at shallower depths. MBES data show two sets of mega-scale lineations indicating at least two fast ice-streaming events of different ages. Contour-parallel recessional morainic ridges mark a stepwise retreat of the grounded ice margin, likely controlled by rising sea levels during deglaciation(s). The different inferred advance and retreat directions of the southern-sourced ice reflect complex geomorphic settings. The overall picture shows that the Chukchi Rise was an area where different ice streams had complex interactions. In addition to glaciogenic deposits, we identify a number of related or preceding seabed features including mounds, gullies/channels, and sediment waves. 2021-04-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/13154 Title: Based Research on International Joint Drilling for Reconstructing Evolution and Glacial History of the Arctic Ocean Authors: Nam, Seung-il 2021-02-26T00:00:00Z https://repository.kopri.re.kr/handle/201206/12359 Title: Application of the PIP25 index for reconstructing spring sea ice concentration in the western Arctic Ocean Authors: Kim, Jung-Hyun; Kim, Dahae; Jun, Sang-Yoon; Joe, Young Jin; Ahn, Youngkyu; Park, Kwangkyu; Nam, Seung-il Abstract: Arctic sea ice plays an important role in the global climate system via the sea ice-albedo feedback. Reliable satellite-derived records of the Arctic sea-ice extent have only been available since 1979. Hence, reconstructions of sea ice conditions on time scales beyond satellite measurements are necessary to understand natural, longer-term sea ice changes and their driving mechanisms under various climate forcings. In this study, we investigated 53 surface sediments collected from the Chukchi Sea and the East Siberian Sea during the Arctic cruises with RV Araon from 2010 to 2019. We aimed to assess the applicability of the PIP25 index, based primarily on the use of HBI III as a semiquantitative sea ice proxy in the western Arctic Ocean. Our preliminary results showed the presence of IP25 in all sediment samples investigated, confirming the occurrence of seasonal sea ice in the study area. Nonetheless, further works are necessary to establish a regional balance factor c value, a term used to calculate the PIP25 index in the western Arctic Ocean. 2020-01-01T00:00:00Z