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Change in Sediment Provenance on the Inner Slope of the Chukchi Rise and Their Paleoenvironmental Implications

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Change in Sediment Provenance on the Inner Slope of the Chukchi Rise and Their Paleoenvironmental Implications applied sciences Article Change in Sediment Provenance on the Inner Slope of the Chukchi Rise and Their Paleoenvironmental Implications Hyo-Jin Koo 1, Young-Keun Jin 2 and Hyen-Goo Cho 1,* 1 Department of Geology, Research Institute of Natural Science, Gyeongsang National University, Jinju 52828, Korea; [email protected] 2 Korea Polar Research Institute (KOPRI), Incheon 21990, Korea; [email protected] * Correspondence: [email protected] Abstract: The Arctic Ocean is one of the world’s most remarkable regions with respect to global climate change. The core ARA09C-St03 was analyzed for mineral composition and Nd isotope to determine the sediment provenance and reconstruct the paleoenvironment in the inner slope of the Chukchi Rise. Core ARA09C-St03 represents overall cycles of brown and gray color with three distinct dark brown layers and two pinkish-white layers and is divided into eight sedimentary units based on the lithological feature. The core has a continuous record of the late marine isotope stage (MIS) 5 to the Holocene and in particular provides a particularly high-resolution record from the Last Glacial Maximum (LGM). Sediment is derived mainly from the adjacent East Siberian Sea and the North American region, and changes in sediment provenance are controlled by climate-dependent particle size. During the glacial/stadial periods, sediments in Units 3, 5, and 8 were supplied by the East Siberian Sea via meltwater-derived suspension. The major ice-rafted debris (IRD) events in Units 2, 4, and 7, characterized by abundant dolomite and K/C ratio, were sourced from North America. The North America-derived materials reflect the initiation and disintegration of the Laurentide Ice Citation: Koo, H.-J.; Jin, Y.-K.; Cho, Sheet and icebergs transported them across the open Arctic Ocean. The differences in provenance H.-G. Change in Sediment within these periods may be related to the scale of the Laurentide Ice Sheet. Interglacial sediments, Provenance on the Inner Slope of the including those from Units 1 and 6, are of mixed origin from Eurasia and the Canadian Archipelago Chukchi Rise and Their and may have been transported by oceanic current and seasonal sea ice. These periods are likely Paleoenvironmental Implications. associated with the negative Arctic Oscillation (AO) intensifying the Beaufort Gyre. Appl. Sci. 2021, 11, 6491. https:// doi.org/10.3390/app11146491 Keywords: Chukchi Sea; mineralogy; Nd isotope; sediment provenance; paleoenvironment Academic Editor: Takaaki Wajima Received: 16 June 2021 Accepted: 12 July 2021 1. Introduction Published: 14 July 2021 The Arctic Ocean is the smallest of the world’s oceans, with a surface area of 9.5 × 106 km2 (2.6% of the world’s ocean) [1]; however, it is one of the most remarkable regions Publisher’s Note: MDPI stays neutral with respect to global climate change. The Arctic Ocean influences the global climate mainly with regard to jurisdictional claims in through seasonal or permanent sea ice cover and deep-water formation controlling oceanic published maps and institutional affil- thermohaline circulation [2]. Climate change in the Arctic Ocean represents an amplified iations. signal of global change [2,3], and paleoenvironmental research can yield important insights into the mechanisms of climate change and thus predict future changes in the climate system. The Arctic Ocean is a unique sea with surrounding continental shelves that make up 52.7% of the Arctic Ocean’s surface area [4]. It is surrounded by the continents of Eurasia Copyright: © 2021 by the authors. and North America and is divided into the western and eastern Arctic by the Lomonosov Licensee MDPI, Basel, Switzerland. Ridge. The western Arctic Ocean includes several seas (the Beaufort, Chukchi, and East This article is an open access article Siberian Seas) and basins (the Amerasian, Chukchi, and Makarov Basins). The Bering Strait distributed under the terms and also connects the Arctic Ocean to the Pacific Ocean with a depth of 50 m. conditions of the Creative Commons Provenance studies provide information on oceanic circulation patterns and clues to the Attribution (CC BY) license (https:// interpretation of the sedimentary environment. Abundant terrigenous material is supplied creativecommons.org/licenses/by/ annually by rivers (227 × 106 t/y) and coastal erosion (~430 × 106 t/y) from the surrounding 4.0/). Appl. Sci. 2021, 11, 6491. https://doi.org/10.3390/app11146491 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, 6491 2 of 15 continents [5,6]. The Arctic Ocean is additionally characterized by permanent sea ice cover, which causes low biological production compared to other oceans [7,8]. Thus, the sediments in the Arctic are mainly composed of terrigenous materials from the surrounding land masses, and the mineral assemblages are very useful for identifying source areas. Terrigenous materials from surrounding continents can be transported by oceanic cur- rents, sea ice, and icebergs, depending on the marine environment in the Arctic Ocean; thus, identification of source areas of terrigenous sediments provides important information on the transporting pathway and the surface circulation patterns [8–11]. The Arctic’s surface ocean circulation consists of two circulation systems, the Beaufort Gyre (BG) and the Transpolar Draft (TPD), which are regulated by Arctic Oscillation (AO) as shown in Figure1[ 11–14]. In addition, coastal currents flow in the Beaufort Sea and Siberian Sea and are met by some inflows through the Bering Strait [15–17]. Clay minerals are very fine-grained and can thus be transported over long distances by ocean currents. Coarser particles can only be transported to sites far from the source area by sea ice or icebergs. In particular, IRD coarser than 250 µm is generally believed to be transported exclusively by icebergs [8,10,18]. Discrimination of sediment sources and reconstruction of paleoenvironmental changes can be undertaken based on grain size, mineralogy, and elemental signals. In particular, clay mineralogy and geochemistry have been utilized as powerful tools with which to trace the provenance of terrigenous portions of marine sediments. Several provenance studies have been performed in the Arctic Ocean, using clay mineralogy [19–21], bulk mineral- ogy [8–10,22,23], Fe-oxide grains [11,14], and geochemical signals [24,25]. These studies have suggested that the Eurasian and North American continents were the major sediment Appl. Sci. 2021, 11, x FOR PEER REVIEW 3 of 16 sources in the western Arctic [8–10,21–23]. Because these source areas have different rocks and tectonics, it is easy to identify their provenance through mineralogy and radiogenic isotopes. FigureFigure 1.1. SchematicSchematic mapmap showingshowing thethe locationlocation ofof core ARA09C-St03ARA09C-St03 inin thethe presentpresent studystudy andand otherother sedimentsediment recordsrecords usedused forfor comparisoncomparison inin thethe presentpresent studystudy (PC04,(PC04, [[21]21];; 03M03,03M03, [[23]23])) inin thethe westernwestern Arctic.Arctic. TheThe circulationcirculation pathspaths (arrow)(arrow) areare modifiedmodified [[14,17]14,17].. BG:BG: BeaufortBeaufort Gyre.Gyre. ESCC:ESCC: EastEast SiberianSiberian CoastalCoastal Current.Current. TPD:TPD: TranspolarTranspolar Drift.Drift. AO+AO+ andand AO-AO- indicateindicate thethe pathspaths ofof currentscurrents inin thethe positivepositive andand negativenegative phasesphases ofof thethe ArcticArctic Oscillation,Oscillation, respectively. respectively. Distribution of various terrigenous components in the Arctic sediment records con- veys information on sediment sources and depositional environments and thus paleocir- culation and changes in paleoclimate conditions, such as connection to other oceans and build-up/disintegration of ice sheets [9,14,25,26]. The Chukchi Rise to Chukchi Basin areas are a sensitive region not only for oceanic currents such as Beaufort Gyre and coastal cur- rents but also for the development of ice sheets, and thus these areas can provide useful records for understanding the evolution of ice and current patterns. However, previous studies in this area have mainly focused on the sedimentation patterns and marine envi- ronment [9,21,23,27] and have not dealt with detailed sediment provenance changes. Fur- thermore, the sediment cores in the Chukchi Basin have limited records during the MIS 2 due to low sedimentation rate [9,23,27]. In this study, the core ARA09C-St03 on the inner slope of the Chukchi Rise is used to provide a continuous sedimentary record containing the MIS 2 period (Figure 2). We an- alyzed the bulk and clay mineral compositions and Nd isotope of the sediment core for the identification of sediment provenance. The main objectives are to reconstruct the pale- oenvironmental change including the sediment transport mechanisms and oceanic cur- rents based on the determined sediment provenance in the inner slope of the Chukchi Rise. Appl. Sci. 2021, 11, 6491 3 of 15 Distribution of various terrigenous components in the Arctic sediment records conveys information on sediment sources and depositional environments and thus paleocirculation and changes in paleoclimate conditions, such as connection to other oceans and build- up/disintegration of ice sheets [9,14,25,26]. The Chukchi Rise to Chukchi Basin areas are a sensitive region not only for oceanic currents such as Beaufort Gyre and coastal currents but also for the development of ice sheets, and thus these areas can provide useful records for understanding
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