https://repository.kopri.re.kr/handle/201206/5302 2026-03-16T17:23:52Z https://repository.kopri.re.kr/handle/201206/16195 Title: Non-linear response of glacier melting to Holocene warming in Svalbard recorded by sedimentary iron (oxyhydr)oxides Authors: Jang, Kwangchul; Germain Bayon; Christoph Vogt; Matthias Forwick; Ahn, Youngkyu; Kim, Jung-Hyun; Nam, Seung-il Abstract: The recent acceleration of ice-sheet loss with its direct impact on sea-level rise and coastal ecosystems is of major environmental and societal concern. However, the effect of atmospheric temperature increases on long-term glacier retreat remains poorly defined due to limited historical observations and uncertainties in numerical ice-sheet models, which challenges climate change adaptation planning. Here, we present a novel approach for investigating the time-transgressive response of Arctic glaciers since the last deglaciation, using glacially-derived Fe-(oxyhydr)oxide layers preserved in glacimarine sediments from a large fjord system in Svalbard. Glacial weathering releases large amounts of Fe, resulting in the deposition of Fe-(oxyhydr)oxide particulates in nearby marine sediments, which can serve as fossil indicators of past glacial melting events. Our results indicate that Svalbard glaciers retreated at a rate of 18 to 41 m/yr between 16.3 and 10.8 kyr BP, synchronously with the progressive rise in atmospheric and oceanic temperatures. From 10.8 kyr BP, glacier retreat markedly accelerated (up to ~116 m/yr) when regional atmospheric temperatures exceeded modern values. Coupled with field observations, this finding directly supports a non-linear response of glacial melting to summer air temperature increases. In addition to suggesting that ice-sheet loss and sea-level rise may further accelerate in the near future, this study paves the way for the use of sedimentary Fe-(oxyhydr)oxide layers in subarctic environments for reconstructing past glacial dynamics. 2023-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/13003 Title: Glacial and environmental changes in northern Svalbard over the last 16.3 ka inferred from neodymium isotopes Authors: Jang, Kwangchul; Ahn, Youngkyu; Joe, Young Jin; Braun, Carmen A.; Joo, Young Ji; Kim, Jung-Hyun; Bayon, Germain; Forwick, Matthias; Vogt, Christoph; Nam, Seung-il Abstract: The reconstruction of past ice sheet extents and dynamics in polar regions is essential for understanding the global climate system and obtaining more reliable predictions of future climate change. Here, we present a multi-proxy dataset integrating the Nd isotopic compositions (εNd) of paired detrital and authigenic iron oxide fractions, grain size distributions, organic geochemistry, and mineral assemblages in a glacimarine sediment core (core HH17-1085-GC) retrieved from the continental shelf off northern Svalbard. Our results indicate variability in sediment provenance and chemical weathering patterns since the last deglaciation, allowing us to distinguish a succession of distinct paleoclimate events: 1) a general retreat of the Svalbard-Barents Sea Ice Sheet (SBIS) from the continental shelf before ca. 16.3 ka BP; 2) an intense episode of meltwater discharge related to massive glacier loss between ca. 12.1 ？ 9.9 ka BP; and 3) a period of reduced meltwater input between ca. 9.9 and ca. 2.7 ka BP followed by 4) a phase of glacier re-advance over the last two millennia. Evidence for the prolonged supply of radiogenic detrital εNd and dolomite at the site of core HH17-1085-GC indicates that the onset of deglaciation offshore northeastern Svalbard may have occurred at least 1 ka later than that at the northwestern shelf, which can be further evaluated by obtaining a more precise end-member determination for the northeastern source with a quantitative εNd dataset from Nordaustrandet. In the context where both polar sea-ice and oceanic circulation are expected to have played minor roles in determining the εNd composition of sedimentary Fe oxyhydroxide phases, the evidence for pronounced Nd isotopic decoupling between paired authigenic and detrital signatures (？εNd) at ca. 15.2 and 14.1 ka BP is interpreted as reflecting chemical weathering changes following the retreat of the SBIS on northern Svalbard, probably corresponding to punctual episodes of glacial re-advances. Our findings provide a better understanding of the deglacial history of northern Svalbard during and after the last deglaciation and highlight the utility of Nd isotopes as a proxy for reconstructing paleo-cryosphere changes. 2021-06-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/12094 Title: Neodymium isotope constraints on chemical weathering and past glacial activity in Svalbard Authors: Jang, Kwangchul; Bayon, Germain; Han, Yeongcheol; Joo, Young Ji; Kim, Ji-Hoon; Ryu, Jong-Sik; Woo, Jusun; Forwick, Matthias; Szczucinski, Witold; Kim, Jung-Hyun; Nam, Seung-il Abstract: Neodymium (Nd) isotopes in leached authigenic components of marine sediments have been increasingly used as a tracer of past ocean-water masses. Despite the general assumption that the Nd isotopic composition of solutes released during chemical weathering fingerprints the source rocks on continents, preferential dissolution of easily dissolvable phases may result in significant deviations in Nd isotopic composition between the solutes and the source rocks, with potential implications for the utility of Nd isotopes in paleoenvironmental studies. Here, we present the Nd isotopic compositions of leached and detrital fractions separated from bedrock and marine sediment samples from the Svalbard archipelago. Our goal is to further understand the behaviour of Nd isotopes during chemical weathering in glacial catchments and evaluate how glacier fluctuations and associated weathering congruency may have affected the export of dissolved Nd isotope signatures to seawater. Our results confirm that terrestrial weathering on Svalbard causes considerable Nd isotopic decoupling between the leached and detrital fractions of fjord sediments (△εNd), resulting from the preferential dissolution of marine precipitates in glaciated catchments dominated by sedimentary rocks. We also show that the degree of Nd isotopic decoupling has fluctuated in response to climate variability on Svalbard during the Holocene, which is also as suggested by the occurrence of generally higher △εNd values during periods of glacier advances in sediment cores retrieved from two different fjords (Dicksonfjorden and Woodfjorden). We posit that the high △εNd values can be ascribed to incongruent chemical weathering of fresh rock flour produced by glacial abrasion. This finding suggests that the degree of Nd isotopic decoupling could be used as a new proxy for tracing glacial fluctuations and associated glacier-derived nutrient inputs to the marine realm. 2020-07-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/12308 Title: Spatial and temporal variations in the detrital and authigenic neodymiumisotopic compositions of Svalbard fjord sediments Authors: Jang, Kwangchul; Nam, Seung-il; Kim, Jung-Hyun; Forwick, Matthias; Szczucinski, Witold Abstract: Detrital and authigenic neodymium isotopes (143Nd/144Nd; "Nd) have been demonstrated to be useful tracers for sediment provenance and water mass composition because of their limited incongruent weathering and short oceanic residence time. As the sediment transport and hydrology of fjord systems in Svalbard are mainly governed by glacier retreat and advance, tracing of sediment provenance and water mass composition using these two proxies is essential to understand the environmental change in Svalbard fjords. Surface sediments obtained from various fjords on Svalbard, i.e. Dicksonfjorden, Hornsund, Isfjorden, Van Mijenfjorden, Wijdefjorden and Woodfjorden, were analysed with regard to detrital and authigenic neodymium isotope ratios with the purpose of tracing spatial variation in sediment provenance and water mass composition, as well as to test their potential application in palaeoclimatic and paleoceanographic studies of fjord sediments Detrital and authigenic "Nd values are spatially variable, ranging from -25 (-15) to -10 (-9), and they correlate generally well (r = 0.62, n = 45). We attribute the fluctuation in "Nd to various types and ages of bedrocks in the drainage area. The fluctuation in "Nd is the largest in Hornsund (-25 to -10 for detrital "Nd and -14 to -9 for authigenic "Nd) where the eroded rocks include pre-Devonian metamorphic rocks and various younger sedimentary rocks (e.g. limestones, sandstones, shales). The similar spatial patterns between detrital and authigenic "Nd indicate that local water circulation generally exerts influence of the sediment provenance, as well as the water mass composition in Hornsund. On the other hand, "Nd values in Dicksonfjorden and the Woodfjorden vary from -14 (-12) to -13 (-11), indicating that similar bedrocks, i.e. Devonian red sandstone ("Nd = -13.6), occur in the drainage areas of both fjords. In addition to surface samples, we investigated two sediment cores from Dicksonfjorden (HH16-1202) and the Woodfjorden (HH12-964), respectively, to reconstruct temporal variations in lithological sediment provenance and water-mass composition through time. Minor temporal variations in detrital and authigenic "Nd measured on two sediment cores shows that the Devonian red sandstone has also been the dominant bedrock in meltwater drainage area during the Holocene. However, the overall decreasing "Nd trend in Dicksonfjorden may result from the change in meltwater drainage by landward glacier retreat. The temporal variation in authigenic "Nd does not well correspond to detrital "Nd, in particular in Woodfjorden, reflecting that the water mass composition in Woodfjorden has been also affected variations in external input, such as the inflow of Atlantic Water and/or changes in local meltwater discharge from surrounding glaciers. 2019-01-01T00:00:00Z