Site U1425

Tada, Ryuji; Murray, R. W.; Zarikian, C.A. Alvarez; Anderson, William T.; Bassetti, Maria Angela; Brace, B.J.; Clemens, S.C.; Gurgel, M.H. da Costa; Dickens, G. R.; Dunlea, Ann G.; Gallagher, S.J.; Giosan, Liviu; Henderson, A.C.G.; Holbourn, Ann; Ikehara, Ken; Irino, Tomohisa; Itaki, Takuya; Karasuda, Akinori; Kinsley, Christopher W.; Kubota, Yoshimi; Lee, G.S.; Lee, K.E.; Lofi, Johanna; Lopes, C.I.C.D.; Peterson, L.C.; Saavedra‐Pellitero, Mariem; Sagawa, Takuya; Singh, Raj K.; Sugisaki, Saiko; Toucanne, Samuel; Wan, Sui; Xuan, Chuang; Zheng, Hairong; Ziegler, Martin

doi:10.2204/iodp.proc.346.106.2015

Cited by 9 publications

(31 citation statements)

References 45 publications

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“…As such, Tada et al . [] showed that the subsurface anoxic layer of the East Sea bottom sediments had the highest absorbance of interstitial water.…”

Section: Resultsmentioning

confidence: 98%

Significant anaerobic production of fluorescent dissolved organic matter in the deep East Sea (Sea of Japan)

Kim

2016

Geophysical Research Letters

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The distribution of fluorescent dissolved organic matter (FDOM) in the East Sea (Sea of Japan) was examined by excitation‐emission matrix spectroscopy with parallel factor analysis (PARAFAC). Humic‐like FDOM (FDOMH) increased with depth and was significantly correlated with Apparent Oxygen Utilization (AOU), indicating that FDOMH in the deep water is mainly produced by oxidation of organic matter. In addition, a surprisingly large excess of FDOMH relative to that expected from the observed AOU was found from 1000 m to the bottom (up to 3500 m). Based on the high‐resolution geographical distribution and characteristics of FDOM in the East Sea, we conclude that this excess likely originates from anaerobic FDOMH production in subsurface bottom sediments. This FDOMH flux accounts for 8–15% of the total FDOM production in the water column. Our results suggest that anaerobic activities in subsurface sediments are an important hidden source of FDOM in the ocean.

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“…As such, Tada et al . [] showed that the subsurface anoxic layer of the East Sea bottom sediments had the highest absorbance of interstitial water.…”

Section: Resultsmentioning

confidence: 98%

Significant anaerobic production of fluorescent dissolved organic matter in the deep East Sea (Sea of Japan)

Kim

2016

Geophysical Research Letters

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“…This subunit is characterized by decimeter-to meter-scale cyclic alternation of dark gray diatom ooze and moderate to heavily bioturbated clayey diatomaceous ooze. A fine lamination of diatom ooze occurring within a dark organic-rich layer extending to a thickness of about 1.5 m has been recognized at 275 m core depth below seafloor (CSF-A) (Tada et al 2015a), which corresponds to about 287 m CCSF-D (Irino et al 2018). Based on the age model of Kamikuri et al (2017), these laminations occurred about 8 Ma.…”

Section: Sites Studiedmentioning

confidence: 98%

“…Sediment cores were collected from seven sites covering wide latitudinal and depth ranges in the Japan Sea. We selected samples collected at Sites U1425 and U1430 in the central and southcentral parts of the Japan Sea during IODP Expedition 346 because hemipelagic sediments covering the middle Miocene to Pliocene were retrieved (Tada et al 2015a(Tada et al , 2015b. We analyzed 154 sediment core samples collected at Site U1425 (about 2000 m deep) and 51 samples collected at Site U1430 (about 1000 m deep) to reconstruct past paleoceanography of the Japan Sea since the late Miocene.…”

Section: Objective and Strategymentioning

confidence: 99%

“…Site U1425 is located in the central part of the Japan Sea, in the middle of the Yamato Bank (1909 m water depth) at 39°29.44′ N and 134°26.55′ E (Tada et al 2015a). The drilling at Site U1425 recovered a total of 417.5 m of sediment (recovery rate of 98%).…”

Section: Sites Studiedmentioning

confidence: 99%

“…The drilling at Site U1425 recovered a total of 417.5 m of sediment (recovery rate of 98%). The description of the sediment core lithology at Site U1425 given below follows that of Tada et al (2015a).…”

Section: Sites Studiedmentioning

confidence: 99%

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Paleoceanographic history of the Japan Sea over the last 9.5 million years inferred from radiolarian assemblages (IODP Expedition 346 Sites U1425 and U1430)

Matsuzaki

Itaki

Tada

et al. 2018

Prog Earth Planet Sci

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Previous studies showed that the evolution of the Japan Sea paleoceanography since the Miocene has been influenced by the regional tectonism (e.g., opening/closing of the connecting seaways) and regional/global climate. In the Japan Sea, Expedition 346 of the Integrated Ocean Drilling Program (IODP) retrieved core sediments dating back to the Miocene at two sites (U1425 and U1430). In this study, we reconstruct shallow-to-deep-water hydrography of the Japan Sea during the Mio-Pliocene based on radiolarian assemblages at Sites U1425 and U1430 considering the local tectonism and changes in global/regional climate. Our data suggest that glacioeustatic sea-level changes have probably had an influence on the local paleoceanography between 9.5 and 7.0 Ma. Indeed, warm water probably flowed from the North Pacific into the Japan Sea when sea level was high via shallow central and eastern seaways. In addition, the sill depth of the northern seaway was probably close to 1000 m between 9.5 and 7.8 Ma and had probably allowed inflow of oxygen minimum zone water from the North Pacific to the Japan Sea when sea level was high. In contrast, our data imply that Cycladophora nakasekoi, an endemic species to the Japan Sea, dominated between 9.5 and 7.3 Ma when sea level was low. Our data also suggest a progressive shoaling of the sill for the period since 7.8 Ma and that global climatic events such as such the late Miocene cooling (7.5-5.5 Ma) and the early Pliocene warmth have had a sustained influence on the Japan Sea. During the mid-Pliocene, a deep cooling of the subsurface to intermediate water of the Japan Sea likely occurred because species related to subarctic subsurface to intermediate waters were dominant between 5 and 3.8 Ma. The Northern Hemisphere Glaciation (ca. 3.0-2.7 Ma) and Mid-Pleistocene Transition (1.2-0.8 Ma) have both likely intensified the cooling of the Japan Sea.

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Weakened pacific overturning circulation, winter monsoon dominance and tectonism re-organized Japan Sea paleoceanography during the Late Miocene global cooling

Matsuzaki

Ikeda

Tada

2022

Sci Rep

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The Late Miocene global cooling (LMGC; approximately 7.9–5.8 Ma) was associated with remarkable changes in monsoon dynamics, biogenic bloom in the global oceans, and the rise of modern ecosystems at the expense of old biota. However, the possible linkage between the environmental changes and ecosystem shifts during the LMGC is still debated. In this paper, we show the high-resolution changes in the fluxes of selected radiolarian species, suggesting a drastic reorganization in the paleoceanography and ecosystem in the Japan Sea during the LMGC. The endemic radiolarian Cycladophora nakasekoi dominated the Japan Sea until 7.4 Ma when the Japan Sea sediment changed from dark radiolarian-rich sediment to organic-poor diatom ooze. Changes in the fluxes of C. nakasekoi and Tricolocapsa papillosa, the latter related to changes in the Pacific central water (PCW), show 100, 200, and ~ 500 ka cycles with their high flux mostly within the darker sediment intervals during the low-eccentricity period until 7.4 Ma, suggesting that orbitally paced PCW inflow might have been the major nutrient source into the Japan Sea. At about 7.4 Ma, these species decreased at the expense of increased Larcopyle weddellium, a radiolarian related to the North Pacific intermediate water (NPIW), and Cycladophora sphaeris, a subarctic radiolarian species, implying a decrease in PCW inflow and an increase in the inflow of NPIW and subarctic shallow water. Such a change would have been related to the LMGC-induced weakening in the Pacific Meridional overturning circulation and the southward shift of the subarctic front due to intensified East Asian winter monsoon. Such a drastic reorganization in the hydrography in the Japan Sea probably caused changes in nutrient provenance from the PCW to the NPIW and resulted in faunal turnover, marked by the disappearance of the old regional and endemic faunal components, such as C. nakasekoi.

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Site U1425

Abstract: Chapter contents Background and objectives. .

Cited by 9 publications

References 45 publications

Significant anaerobic production of fluorescent dissolved organic matter in the deep East Sea (Sea of Japan)

Significant anaerobic production of fluorescent dissolved organic matter in the deep East Sea (Sea of Japan)

Paleoceanographic history of the Japan Sea over the last 9.5 million years inferred from radiolarian assemblages (IODP Expedition 346 Sites U1425 and U1430)

Weakened pacific overturning circulation, winter monsoon dominance and tectonism re-organized Japan Sea paleoceanography during the Late Miocene global cooling

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