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Reconstruction of late Quaternary glacial History and Paleoceanographic changes in the Western Arctic 이미지
Practical task Reconstruction of late Quaternary glacial History and Paleoceanographic changes in the Western Arctic
Research period 2014/01 ~ 2016/12
Responsible person Seung Il Nam Research result

Detail


Reading Sediment Cores to Understand Climate Change in the Arctic Ocean


Reconstruction of Late Quaternary glacial History and Paleoceanographic changes in the Western Arctic



Seung Il Nam sinam@kopri.re.kr




The role of the Arctic Ocean in global ocean circulation and climate change is well known. Moreover, recent observation and modelling of Arctic climate changes clearly indicate that recent global warming has been associated with the rapid reduction of Arctic sea ice.


The western Arctic, including the Chukchi Sea between the Chukchi Borderland and the East Siberian Sea, is of special importance, as the retreat in sea ice over the previous decades appears to be most drastic in these areas in comparison to other marginal Arctic seas.


In general, the western Arctic is connected to the Pacific Ocean through the Bering Strait(Fig. 1), the pathway for the inflow of nutrient-rich, low-saline North Pacific Water(i.e. the Bering Strait Inflow, BSI). With a present depth of only around 30-50m, the Bering Strait formed a land bridge between Alaska and Siberia during the last glacial period due to its low sea level.


This low sea level led to a strongly limited or even interrupted influx of the BSI into the Arctic Ocean during the late Quaternary glacial-interglacial cycles,resulting in broadly different hydrographic and environmental conditions in comparison to today.


Since 2011, KOPRI conducted five Arctic expeditions (ARA02B, 03B, 04B, 04C, 6C) aboard IBRV Araon, in order to acquire bathymetry with multi-beam and shallow seismic profiles using SBP and to collect sediment cores in the western Arctic Ocean.


In particular, the 6th IBRV Araon Arctic expedition(ARA06C) was conducted in the West Arctic across the continental margin of the Chukchi and East Siberian Seas in 2015. A glaciomarine sediment core of around 14m in length, which is the longest core ever recovered in the Arctic basin, was successfully retrieved using the jump piston corer(JPC) that was newly installed on RV Araon. 


Based on correlation data set estimated through MSCL-XRF core scanning using previously-published lithostratigraphy established from the western Arctic sediments, ca. 14m-long glaciomarine sediment core may record the middle Quaternary glacial history and paleoclimate/paleoceanographic changes for the past 600ka BP.


New scientific findings gained from the westernArctic Ocean would contribute to the International Ocean Discovery Program drilling on southern Lomonosov Ridge in 2016, allowing KOPRI to submit new proposalsto understand the evolutionary history of the Arctic Ocean and to reconstruct the Quaternary glacial history and paleoclimatic and paleoceanograhic changes in the western Arctic Ocean.


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Figure1.The map shows seismic survey lines with the JPC (jumbo piston corer) core sites conducted during the 6th Araon expedition(ARA06C) in 2015 into the western Arctic.

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Figure 2.Ca. 14m-long glacimarine sediment core recovered from the western Arctic Ocean (Chukchi Sea deep basin) using the JPC installed on Rv Araon. The core JPC4mayrepresentmiddle Quaternary glacial history and paleoceanographic changes in the western Arctic.


Figure 3. The sediment core JPC-4 JPC appears to show repeated marine-based glacial presence in the western Arctic and evidence for paleoclimatic changes during the last 500ka BP.






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