Orbital-scale benthic foraminiferal oxygen isotope stratigraphy at the northern Bering Sea Slope Site U1343 (IODP Expedition 323) and its Pleistocene paleoceanographic significance

Asahi, Hirofumi; Kender, Sev; Ikehara, Minoru; Sakamoto, Tatsuhiko; Takahashi, Kozo; Ravelo, Ana Christina; Zarikian, C.A. Alvarez; Khim, Boo‐Keun; Leng, Melanie J.

doi:10.1016/j.dsr2.2014.01.004

Cited by 34 publications

(37 citation statements)

References 65 publications

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“…IODP Exp 323 MPT MPT Fig. 5 Stroynowski et al, 2015;Onodera et al, 2016;Teraishi et al, 2016 Site (Rohling et al, 2014); benthic foraminiferal δ 18 O (site U1342: Knudson and Ravelo, 2015a; Site U1343: Asahi et al, 2016;site U1345: Cook et al, 2016; Δδ 13 C between Site U1342 (Knudson and Ravelo, 2015a) and Site 889 in the eastern equatorial Pacific (Mix et al, 1995); bulk δ 15 N (Knudson and Ravelo, 2015b); diatom assemblage at site U1341 (Onodera et al, 2016) and Site U1343 (Teraishi et al, 2016); and radiolarian C. davisiana at Sites U1341 (Ikenoue et al, 2016) and U1343 (Takahashi et al, 2011a). The thick lines in the δ 18 O, Δδ 13 C, and δ 15 N plots were smoothed using a 10 kyr moving window.…”

Section: Mptmentioning

confidence: 99%

“…Site U1340 Schlung et al, 2013Riethdorf et al, 2013Max et al, 2012Max et al, , 2014 Site U1340 Hu et al, 2010Caissie et al, 20166 Kallmeyer et al, 2012Engelhardt et al, 2014;Wehrmann and Ferdelman, 2014 Sites U1343, U1344, U1345 Wehrmann, et al, 201620 Pierre et al, 201610 Cook et al, 2005Knudson and Ravelo, 2015a;Asahi et al, 2016;Cook et al, 2016Asahi et al, 2016Cook et al, 2016 Ba Fe Soyol-Erdene and Huh, 2013 März et al, 2014IODP Exp 323 März et al, 2014 , , ,…”

Section: Mptunclassified

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Paleoceanography of the Bering Sea advanced by IODP Expedition 323:

Asahi

Takahashi

Okazaki

et al. 2018

Jour. Geol. Soc. Japan

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Our understanding of the paleoceanography of the Bering Sea has been considerably advanced by IODP Expedition. The expedition aimed to create a high-resolution record of changes in paleoceanography since the Pliocene in a relatively high-latitude region of the North Pacific, subject to polar amplification. The expedition recovered cores, mainly high-quality Advanced Piston Cores (APC), with a total length of m of continuous cores from seven sites distributed around the perimeter of the Aleutian Basin, including the Bowers Ridge, the Bering Slope edge, and the Umnak Plateau. These cores are crucial to our understanding of sea-ice distribution, productivity, laminated sediments, input of detrital materials, the formation of the North Pacific Intermediate Water mass, the Pacific water mass entry, the history of the Arctic gateway, and the enigma of the intensification of the Northern Hemisphere Glaciation and the mid-Pleistocene Transition. The maximum ages of the cores are ~ Ma at the Bowers Ridge sites and. Ma at the Bering Slope sites. Meltwater from the Alaskan Ice Sheet has influenced the Bering Sea since. Ma, increasing in influence at. and .-. Ma. The significant development of sea-ice formation was identified at two sites on the Bowers Ridge at. and .-. Ma, based on analysis of sea-ice related diatoms and silicoflagellates. Such sea-ice formation affected the extent of the North Pacific Intermediate Water in the Bering Sea, which was strengthened during cold intervals such as when the Bering Strait closed due to falling sea level.

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Section: Mptmentioning

confidence: 99%

Section: Mptunclassified

Paleoceanography of the Bering Sea advanced by IODP Expedition 323:

Asahi

Takahashi

Okazaki

et al. 2018

Jour. Geol. Soc. Japan

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“…그러나 Site U1343이 위치한 베링해 대륙사면은 대륙으로부터 비교적 가깝고, 대륙붕 수괴의 영향으로 해수의 철의 농도가 상대적으로 높기 때 문에 영양염 이용률도 높게 관찰된다 (Garcia et al 2010;Springer et al 1996). Asahi et al (2016)은 저서성 유공충의 산소동위원소 값 을 측정하여 설정한 층서를 바탕으로 Site U1343의 연대 를 결정하였다 (Fig. 3).…”

Section: 서 론unclassified

Reconstruction of Nitrate Utilization Rate Change Based on Diatom-bound Nitrogen Isotope Values in the Central Slope Area of the Bering Sea during the Early Pleistocene (2.4-1.25 Ma)

Kim¹,

Khim²

2016

Ocean and Polar Research

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: Because the high latitude region in the North Pacific is characterized by high primary production in the surface water enriched with nutrients, it is important to understand the variation of surface water productivity and associated nutrient variability in terms of global carbon cycle. Surface water productivity change or its related nutrient utilization rate during the Northern Hemisphere Glaciation (NHG; ca. 2.73 Ma) has been reported, but little is known about such circumstances under gradual climate cooling since the NHG. Bulk nitrogen isotope (δ 15 N bulk ) of sedimentary organic matter has been used for the reconstruction of nutrient utilization rate in the surface water. However, sedimentary organic matter experiences diagenesis incessantly during sinking through the water column and after burial within the sediments. Thus, in this study we examine the degree of nitrate utilization rate during the early Pleistocene (2.4−1.25 Ma) since the NHG, using the diatom-bound nitrogen isotope (δ 15 N db ), which is known to be little influenced by diagenesis, from Site U1343 in the Bering slope area. δ 15N db values range from ~0.5 to 5.5‰, which is lower than δ 15N bulk values, but they vary with larger amplitude. Variation patterns between δ 15N db values and biogenic opal concentration are generally consistent, which indicates that the nitrate utilization rate is closely related to opal productivity change in the surface water. A positive correlation between opal productivity and nitrate utilization rate was observed, which is different from the other high latitude regions in the North Pacific. The main reason for this contrasting relationship is that the primary production in the surface water at Site U1343 is influenced mostly by the degree of sea ice formation. Still, although concerns about diagenetic alteration have been avoided by using δ 15 N db , the effects of the preservation state of biogenic opal and the speciesdependent isotopic fractionation on δ 15 N db should be assessed in the future studies.

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“…The red lines in (G,H) show the depth of SMTZ (Wehrmann et al, 2011). The age model was based on Horikawa et al (2015) for Site U1341, Asahi et al (2014) for Site U1343, and Okazaki et al (2016) and Takahashi et al (2011b) for Site U1344. Temperature are estimated by extrapolating the geothermal gradients measured at depths down to 130-140 mbsf.…”

Section: Xrd Analysis Of the Clay-size Fractionmentioning

confidence: 99%

“…These splits were retrieved at intervals of ∼1.6 m at 0-145 mbsf and ∼5 m at 330-745 mbsf. We used an age model for Site U1343 based on oxygen isotope stratigraphy of benthic foraminifers for the same site (Asahi et al, 2014;Kim et al, 2015) to classify the XRD data from Site U1343 into glacial or interglacial sediments.…”

Section: X-ray Diffraction Analysis Of the Clay-size Fractionmentioning

confidence: 99%

Low-Temperature Clay Mineral Dehydration Contributes to Porewater Dilution in Bering Sea Slope Subseafloor

et al. 2018

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Widespread diagenesis of clay minerals occurs in deeply buried marine sediments under high-temperature and high-pressure conditions. For example, the smectite-to-illite (S-I) transformation has been often observed in sediments at in situ temperatures above ∼60 • C. However, it remains largely unknown whether such diagenetic processes naturally occur in relatively shallow and low-temperature sediments and, if so, what the consequences are of any related chemical reactions to the geochemical characteristics in the deep biosphere. We evaluated the possibility of naturally occurring S-I transformation at temperatures below 40 • C in continental slope sediments of the Bering Sea by examining porewater chemistry, clay mineralogy, and chemical composition of clay minerals measured to ∼800 m beneath the seafloor (mbsf) in core samples acquired during Integrated Ocean Drilling Program Expedition 323. In porewater from these cores, chloride concentrations decreased with increasing depth from 560 mM near the seafloor to 500 mM at ∼800 mbsf; δ 18 O increased from 0 to 1.5‰; and δD decreased from −1 to −9‰. These trends are consistent with the addition of water derived from S-I transformation. The discrete low Cl − spikes observed between ∼200 and ∼450 mbsf could be attributed to the dissociation of methane hydrate. X-ray diffraction analysis of the clay-size fraction (<2 µm) showed an increase of illite content in the I/S mixed layer with increasing depth to 150 mbsf. This increase may imply the occurrence of S-I transformation. The decrease of Fe 3+ /Fe 2+ in the clay-size fraction with increasing depth strongly suggests microbial reduction of Fe(III) in clay minerals with burial, which also has the potential to promote the S-I transformation. Our results imply the significant ecological roles on the diagenesis of siliciclastic clay minerals underlying the high-productivity surface seawater at continental margins.

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Orbital-scale benthic foraminiferal oxygen isotope stratigraphy at the northern Bering Sea Slope Site U1343 (IODP Expedition 323) and its Pleistocene paleoceanographic significance

Cited by 34 publications

References 65 publications

Paleoceanography of the Bering Sea advanced by IODP Expedition 323:

Paleoceanography of the Bering Sea advanced by IODP Expedition 323:

Reconstruction of Nitrate Utilization Rate Change Based on Diatom-bound Nitrogen Isotope Values in the Central Slope Area of the Bering Sea during the Early Pleistocene (2.4-1.25 Ma)

Low-Temperature Clay Mineral Dehydration Contributes to Porewater Dilution in Bering Sea Slope Subseafloor

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