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  1. Article ; Online: Intensified East Asian winter monsoon during the last geomagnetic reversal transition

    Yusuke Ueno / Masayuki Hyodo / Tianshui Yang / Shigehiro Katoh

    Scientific Reports, Vol 9, Iss 1, Pp 1-

    2019  Volume 8

    Abstract: Abstract The strength of Earth’s magnetic dipole field controls galactic cosmic ray (GCR) flux, and GCR-induced cloud formation can affect climate. Here, we provide the first evidence of the GCR-induced cloud effect on the East-Asian monsoon during the ... ...

    Abstract Abstract The strength of Earth’s magnetic dipole field controls galactic cosmic ray (GCR) flux, and GCR-induced cloud formation can affect climate. Here, we provide the first evidence of the GCR-induced cloud effect on the East-Asian monsoon during the last geomagnetic reversal transition. Bicentennial-resolution monsoon records from the Chinese Loess Plateau revealed that the summer monsoon (SM) was affected by millennial-scale climate events that occurred before and after the reversal, and that the winter monsoon (WM) intensified independently of SM variations; dust accumulation rates increased, coinciding with a cooling event in Osaka Bay. The WM intensification event lasted about 5000 years across an SM peak, during which the Earth’s magnetic dipole field weakened to <25% of its present strength and the GCR flux increased by more than 50%. Thus, the WM intensification likely resulted from the increased land–ocean temperature gradient originating with the strong Siberian High that resulted from the umbrella effect of increased low-cloud cover through an increase in GCR flux.
    Keywords Medicine ; R ; Science ; Q
    Subject code 550
    Language English
    Publishing date 2019-06-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Sea-level variations during Marine Isotope Stage 7 and coastal tectonics in the eastern Seto Inland Sea area, western Japan

    Sato, Hiroshi / Fumika Ban / Masayuki Hyodo / Shigehiro Katoh

    Quaternary international. 2017 Oct. 15, v. 456

    2017  

    Abstract: Relative sea-level (RSL) observations for Marine Isotope Stage (MIS) 7 were obtained from three sites (Higashinada, Kakogawa and Mitsu) of the eastern Seto Inland Sea area, western Japan. We evaluated the magnitude of sea-level highstands during MIS 7 ... ...

    Abstract Relative sea-level (RSL) observations for Marine Isotope Stage (MIS) 7 were obtained from three sites (Higashinada, Kakogawa and Mitsu) of the eastern Seto Inland Sea area, western Japan. We evaluated the magnitude of sea-level highstands during MIS 7 and the local tectonics based on RSL records of this coastal area. For this purpose, we analyzed diatom assemblages and sedimentary sulfur, and carried out tephra analysis. We also constructed a linear age model to determine the depositional ages of the sediments using altitudes of astronomical age control points obtained mainly from the present diatom data. At the Mitsu site, RSLs were estimated to be −22.87 ± 0.50 m at the MIS 7.5 highstand peak (234.6 ka), below −20.17 m at 211.2 ka, and below −20.00 m at 209.9 ka. With a tectonic subsidence rate of 0.11 ± 0.02 m/ka since the Last Interglacial Maximum at the Mitsu site, the elevation of the tectonically corrected MIS 7.5 highstand peak may have been +2.94 ± 5.19 m. The tectonically corrected sea-level elevations during MIS 7.3 are inferred to have been below +3.06 ± 4.72 m at 211.2 ka and below +3.09 ± 4.70 m at 209.9 ka. Comparisons between the diatom-inferred RSLs and the isotopically derived sea-level curve indicate that the MIS 7.3 highstand peak was above −18 m and may have been lower than the MIS 7.5 and 7.1 highstands. Based on the isotopically derived sea-level curve and the RSL data from Higashinada and Kakogawa, a tectonic subsidence rate of 0.26–0.32 m/ka was derived for Higashinada and a tectonic uplift rate of >0.17 m/ka and <0.29 m/ka was derived for Kakogawa. A relative uplift rate of >0.43 m/ka and <0.61 m/ka was derived along the traverse from Higashinada to Kakogawa. The uplift rate derived for Kakogawa relative to Mitsu is > 0.26 m/ka and <0.42 m/ka. These values indicate the intensity of crustal movements associated with active faulting of the Rokko–Awaji fault system along this tectonically active coast.
    Keywords altitude ; Bacillariophyceae ; coasts ; isotopes ; models ; sea level ; subsidence ; sulfur ; tectonics ; tephra ; Japan
    Language English
    Dates of publication 2017-1015
    Size p. 102-116.
    Publishing place Elsevier Ltd
    Document type Article
    ISSN 1040-6182
    DOI 10.1016/j.quaint.2017.03.042
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: A centennial-resolution terrestrial climatostratigraphy and Matuyama–Brunhes transition record from a loess sequence in China

    Masayuki Hyodo / Kenta Banjo / Tianshui Yang / Shigehiro Katoh / Meinan Shi / Yuki Yasuda / Jun-ichi Fukuda / Masako Miki / Balázs Bradák

    Progress in Earth and Planetary Science, Vol 7, Iss 1, Pp 1-

    2020  Volume 18

    Abstract: Abstract Terrestrial records of the last geomagnetic reversal often have few age constraints. Chronostratigraphy using suborbital-scale paleoceanic events during marine isotope stage 19 may contribute to solving this problem. We applied the method to an ... ...

    Abstract Abstract Terrestrial records of the last geomagnetic reversal often have few age constraints. Chronostratigraphy using suborbital-scale paleoceanic events during marine isotope stage 19 may contribute to solving this problem. We applied the method to an 8 m long, high-resolution paleomagnetic record from a loess sequence in China and revealed millennial-to-sub-centennial scale features of the Matuyama–Brunhes (MB) transition. All samples were subjected to progressive thermal demagnetization with 14–15 steps up to 650–680 °C. As a result, 96% of the samples yielded a high-quality remanent magnetization. The MB transition terminated with a 75 cm thick zone with nine polarity flips. The polarity flip zone, dated at about 779–777 ka, began between the warm events “I” and “J” and terminated at the end of the cooling event coincident with the lowest axial-dipole strength interval. Most polarity flips occurred within 70 years. The virtual geomagnetic poles (VGPs) in the upper polarity flip zone clustered in the SW Pacific region, where the MB transitional VGPs from lavas of the Hawaiian and Canary Islands and lacustrine deposits of Java also clustered. These sites were probably dominated by dipolar fields. The absence of transitional fields across polarity flips implies a short time span for averaging fields due to a thin loess-magnetization lock-in zone. The reverse-to-normal polarity reversal dated at about 778 ka in Lingtai occurred at the end of the SW Pacific VGP zone, an important key bed for MB transition stratigraphy. The reversal is a good candidate for the main MB boundary. We found an excursion at about 766 ka spanning about 1 ka.
    Keywords Loess–paleosol ; Geomagnetic reversal ; Early–Middle Pleistocene transition ; Loess magnetism ; East Asian monsoon ; Geography. Anthropology. Recreation ; G ; Geology ; QE1-996.5
    Subject code 550
    Language English
    Publishing date 2020-06-01T00:00:00Z
    Publisher SpringerOpen
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Millennial-scale northern Hemisphere Atlantic-Pacific climate teleconnections in the earliest Middle Pleistocene

    Masayuki Hyodo / Balázs Bradák / Makoto Okada / Shigehiro Katoh / Ikuko Kitaba / David L. Dettman / Hiroki Hayashi / Koyo Kumazawa / Kotaro Hirose / Osamu Kazaoka / Kizuku Shikoku / Akihisa Kitamura

    Scientific Reports, Vol 7, Iss 1, Pp 1-

    2017  Volume 9

    Abstract: Abstract Suborbital-scale climate variations, possibly caused by solar activity, are observed in the Holocene and last-glacial climates. Recently published bicentennial-resolution paleoceanic environmental records reveal millennial-scale high-amplitude ... ...

    Abstract Abstract Suborbital-scale climate variations, possibly caused by solar activity, are observed in the Holocene and last-glacial climates. Recently published bicentennial-resolution paleoceanic environmental records reveal millennial-scale high-amplitude oscillations postdating the last geomagnetic reversal in the Marine Isotope Stage (MIS) 19 interglacial. These oscillations, together with decoupling of post-reversal warming from maximum sea-level highstand in mid-latitudes, are key features for understanding the climate system of MIS 19 and the following Middle Pleistocene. It is unclear whether the oscillations are synchronous, or have the same driver as Holocene cycles. Here we present a high resolution record of western North Pacific submarine anoxia and sea surface bioproductivity from the Chiba Section, central Japan. The record reveals many oxic events in MIS 19, coincident with cold intervals, or with combined cold and sea-level fall events. This allows detailed correlations with paleoceanic records from the mid-latitude North Atlantic and Osaka Bay, southwest Japan. We find that the millennial-scale oscillations are synchronous between East and West hemispheres. In addition, during the two warmest intervals, bioproductivity follows the same pattern of change modulated by bicentennial cycles that are possibly related to solar activity.
    Keywords Medicine ; R ; Science ; Q
    Subject code 550
    Language English
    Publishing date 2017-08-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: High resolution stratigraphy across the early–middle Pleistocene boundary from a core of the Kokumoto Formation at Tabuchi, Chiba Prefecture, Japan

    Hyodo, Masayuki / Akihisa Kitamura / David L. Dettman / Hayato Matsushita / Ikuko Kitaba / Ikuko Tanaka / Kenta Takasaki / Makoto Okada / Masakazu Nara / Shigehiro Katoh / Takuya Matsuzaki

    Elsevier Ltd and INQUA Quaternary international. 2016 Mar. 18, v. 397

    2016  

    Abstract: We present a detailed stratigraphy of the lithology, sedimentary facies, magnetic susceptibility, and chemical composition of a 54-m thick core sequence drilled adjacent to the Chiba section, a candidate for the Global Boundary Stratotype Section and ... ...

    Abstract We present a detailed stratigraphy of the lithology, sedimentary facies, magnetic susceptibility, and chemical composition of a 54-m thick core sequence drilled adjacent to the Chiba section, a candidate for the Global Boundary Stratotype Section and Point of the early–middle Pleistocene boundary. Siltstones rich in trace fossils are dominant throughout the core, except for the lowermost sand beds. The Byakubi tephra is divided into three units, of which the uppermost (39.54–39.49 m core depth) is identified as a primary bed showing evidence of fallout. The preliminary Matuyama–Brunhes magnetic polarity boundary lies 1 m above the top of the fallout unit. Maximum and minimum susceptibility axes for anisotropy of magnetic susceptibility have shallow (<11°) and steep (>73°) inclinations, respectively, throughout the core. The results suggest that sedimentary structures formed in calm environments remain undisturbed in the sediment. Clustered maximum axis directions indicate the influence of a persistent NW–SE contour current. The homogeneous depositional environment for the siltstone interval is supported by relatively smooth variations in magnetic susceptibility and chemical composition. Stratigraphic correlation with published oxygen isotope data indicates that the depositional age of the core may extend from the end of marine oxygen isotope stage (MIS) 20 to just after mid-MIS 19, from which an average sedimentation rate of 2–2.5 m/ky is estimated. These results suggest that the Chiba section has a high potential to provide an excellent stratotype for the early–middle Pleistocene boundary.
    Keywords anisotropy ; chemical composition ; fossils ; isotopes ; magnetism ; oxygen ; paleoclimatology ; sand ; stratigraphy ; tephra ; Japan
    Language English
    Dates of publication 2016-0318
    Size p. 16-26.
    Publishing place Elsevier Ltd
    Document type Article
    ISSN 1040-6182
    DOI 10.1016/j.quaint.2015.03.031
    Database NAL-Catalogue (AGRICOLA)

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