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  1. Article: Potential photosynthetic impact on phosphate stromatolite formation after the Marinoan glaciation: Paleoceanographic implications

    Shiraishi, Fumito / Akihiro Kano / Chizuru Takashima / Saki Ohnishi / Tomoyo Okumura / Yasutaka Hayasaka / Yusaku Hanzawa

    Sedimentary geology. 2019 Feb., v. 380

    2019  

    Abstract: This study investigated the origin and the depositional age of phosphate stromatolites contained in the Neoproterozoic Salitre Formation, Brazil. The stromatolites exhibited columnar shapes and were intercalated with laminated dolostones. Their ... ...

    Abstract This study investigated the origin and the depositional age of phosphate stromatolites contained in the Neoproterozoic Salitre Formation, Brazil. The stromatolites exhibited columnar shapes and were intercalated with laminated dolostones. Their depositional environment was interpreted to have been an evaporitic ramp where erosion and reworking by waves prevailed. Laser ablation-inductively coupled plasma-mass spectrometry measurements of the stromatolites yielded a UPb age of 616 ± 32 Ma, suggesting that they were deposited after the Marinoan glaciation. Several types of filamentous structures were recognized in the stromatolites; many of them were “pseudofossil” ambient inclusion trails, but some were possibly microfossils. To consider the general presence of photosynthetic microorganisms on the surface of shallow-water stromatolites, the involvement of microbial photosynthesis in phosphate stromatolite formation was expected. Numerical calculations determined that photosynthesis could have induced phosphate mineral precipitation at the time of deposition if the phosphorus concentration was above ca. 5 μM. To achieve such high concentration at the shallow ocean, globally elevated phosphorus concentration was considered to be the ultimate factor in addition to the local process(es) including upwelling and/or evaporation. Therefore, the phosphate stromatolites in the Salitre Formation are evidence of the development of a phosphorus-rich ocean after the Marinoan glaciation.
    Keywords evaporation ; glaciation ; microfossils ; microorganisms ; Neoproterozoic era ; paleoceanography ; phosphates ; phosphorus ; photosynthesis ; spectroscopy ; Brazil
    Language English
    Dates of publication 2019-02
    Size p. 65-82.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 216739-6
    ISSN 0037-0738
    ISSN 0037-0738
    DOI 10.1016/j.sedgeo.2018.11.014
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: Evaluation of nutrient and energy sources of the deepest known serpentinite-hosted ecosystem using stable carbon, nitrogen, and sulfur isotopes.

    Yuji Onishi / Toshiro Yamanaka / Tomoyo Okumura / Shinsuke Kawagucci / Hiromi Kayama Watanabe / Yasuhiko Ohara

    PLoS ONE, Vol 13, Iss 6, p e

    2018  Volume 0199000

    Abstract: The Shinkai Seep Field (SSF) in the southern Mariana forearc discovered in 2010 is the deepest (~5,700 m in depth) known serpentinite-hosted ecosystem dominated by a vesicomyid clam, Calyptogena (Abyssogena) mariana. The pioneering study presumed that ... ...

    Abstract The Shinkai Seep Field (SSF) in the southern Mariana forearc discovered in 2010 is the deepest (~5,700 m in depth) known serpentinite-hosted ecosystem dominated by a vesicomyid clam, Calyptogena (Abyssogena) mariana. The pioneering study presumed that the animal communities are primary sustained by reducing fluid originated from the serpentinization of mantle peridotite. For understanding the nutrient and energy sources for the SSF community, this study conducted four expeditions to the SSF and collected additional animal samples such as polychaetes and crustaceans as well as sediments, fragments of chimneys developing on fissures of serpentinized peridotite, seeping fluid on the chimneys, and pore water within the chimneys. Geochemical analyses of seeping fluids on the chimneys and pore water of the chimneys revealed significantly high pH (~10) that suggest subseafloor serpentinization controlling fluid chemistry. Stable isotope systematics (carbon, nitrogen, and sulfur) among animals, inorganic molecules, and environmental organic matter suggest that the SSF animal community mostly relies on the chemosynthetic production while some organisms appear to partly benefit from photosynthetic production despite the great depth of SSF.
    Keywords Medicine ; R ; Science ; Q
    Subject code 550
    Language English
    Publishing date 2018-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Influence of normal tide and the Great Tsunami as recorded through hourly-resolution micro-analysis of a mussel shell

    Yuji Sano / Tomoyo Okumura / Naoko Murakami-Sugihara / Kentaro Tanaka / Takanori Kagoshima / Akizumi Ishida / Masako Hori / Glen T. Snyder / Naoto Takahata / Kotaro Shirai

    Scientific Reports, Vol 11, Iss 1, Pp 1-

    2021  Volume 12

    Abstract: Abstract We report here hourly variations of Mg/Ca, Sr/Ca, and Ba/Ca ratios in a Mediterranean mussel shell (Mytilus galloprovincialis) collected at the Otsuchi bay, on the Pacific coast of northeastern Japan. This bivalve was living in the intertidal ... ...

    Abstract Abstract We report here hourly variations of Mg/Ca, Sr/Ca, and Ba/Ca ratios in a Mediterranean mussel shell (Mytilus galloprovincialis) collected at the Otsuchi bay, on the Pacific coast of northeastern Japan. This bivalve was living in the intertidal zone, where such organisms are known to form a daily or bidaily growth line comprised of abundant organic matter. Mg/Ca ratios of the inner surface of the outer shell layer, corresponding to the most recent date, show cyclic changes at 25–90 μm intervals, while no interpretable variations are observed in Sr/Ca and Ba/Ca ratios. High Mg/Ca ratios were probably established by (1) cessation of the external supply of Ca and organic layer forming when the shell is closed at low tide, and (2) the strong binding of Mg to the organic layer, but not of Sr and Ba. Immediately following the great tsunami induced by the 2011 Tohoku earthquake, Mg/Ca enrichment occurred, up to 10 times that of normal low tide, while apparent Ba/Ca enrichment was observed for only a few days following the event, therefore serving a proxy of the past tsunami. Following the tsunami, periodic peaks and troughs in Mg/Ca continued, perhaps due to a biological memory effect as an endogenous clock.
    Keywords Medicine ; R ; Science ; Q
    Subject code 551
    Language English
    Publishing date 2021-10-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: Transition of microbiological and sedimentological features associated with the geochemical gradient in a travertine mound in northern Sumatra, Indonesia

    Sugihara, Chiya / Agung Harijoko / Akihiro Kano / Chizuru Takashima / Katsunori Yanagawa / Tomoyo Okumura

    Sedimentary geology. 2016 Aug. 15, v. 343

    2016  

    Abstract: Modern travertines, carbonate deposits in Ca-rich hydrothermal water with high pCO2, often display a changing environment along the water path, with corresponding variability in the microbial communities. We investigated a travertine-bearing hot spring ... ...

    Abstract Modern travertines, carbonate deposits in Ca-rich hydrothermal water with high pCO2, often display a changing environment along the water path, with corresponding variability in the microbial communities. We investigated a travertine-bearing hot spring at the Blue Pool in northern Sumatra, Indonesia. The thermal water of ~62°C with high H2S (200μM) and pCO2 (~1atm) developed a travertine mound ~70m wide. The concentrations of the gas components H2S and CO2, decrease immediately after the water is discharged, while the dissolved oxygen, pH, and aragonite saturation increase in the downstream direction. Responding to the geochemical gradient in the water, the surface biofilms change color from white to pink, light-green, dark-green, and brown as the water flows from the vent; this corresponds to microbial communities characterized by chemolithoautotrophs (Halothiobacillaceae), purple sulfur bacteria (Chromatiaceae), Anaerolineaceae, and co-occurrence of green non-sulfur bacteria (Chloroflexales)-Cyanobacteria, and green sulfur bacteria (Chlorobiales), respectively. In an environment with a certain level of H2S (>1μM), sulfur digestion and anoxygenic photosynthesis can be more profitable than oxygenic photosynthesis by Cyanobacteria. The precipitated carbonate mineral consists of aragonite and calcite, with the proportion of aragonite increasing downstream due to the larger Mg2+/Ca2+ ratio in the water or the development of thicker biofilm. Where the biofilm is well developed, the aragonite travertines often exhibit laminated structures that were likely associated with the daily metabolism of these bacteria. The microbiological and sedimentological features at the Blue Pool may be the modern analogs of geomicrobiological products in the early Earth. Biofilm of anoxygenic photosynthetic bacteria had the potential to form ancient stromatolites that existed before the appearance of cyanobacteria.
    Keywords aragonite ; biofilm ; calcite ; carbon dioxide ; Chlorobiales ; Chloroflexales ; Chromatiaceae ; color ; Cyanobacteria ; dissolved oxygen ; Halothiobacillaceae ; hot springs ; hydrogen sulfide ; microbial communities ; pH ; photosynthesis ; photosynthetic bacteria ; sulfur ; Indonesia
    Language English
    Dates of publication 2016-0815
    Size p. 85-98.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 216739-6
    ISSN 0037-0738
    ISSN 0037-0738
    DOI 10.1016/j.sedgeo.2016.07.012
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

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  5. Article ; Online: Cyanobacterial exopolymer properties differentiate microbial carbonate fabrics

    Fumito Shiraishi / Yusaku Hanzawa / Tomoyo Okumura / Naotaka Tomioka / Yu Kodama / Hiroki Suga / Yoshio Takahashi / Akihiro Kano

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

    2017  Volume 8

    Abstract: Abstract Although environmental changes and evolution of life are potentially recorded via microbial carbonates, including laminated stromatolites and clotted thrombolites, factors controlling their fabric are still a matter of controversy. Herein, we ... ...

    Abstract Abstract Although environmental changes and evolution of life are potentially recorded via microbial carbonates, including laminated stromatolites and clotted thrombolites, factors controlling their fabric are still a matter of controversy. Herein, we report that the exopolymer properties of different cyanobacterial taxa primarily control the microbial carbonates fabrics in modern examples. This study shows that the calcite encrustation of filamentous Phormidium sp. secreting acidic exopolymers forms the laminated fabric of stromatolites, whereas the encrustation of coccoid Coelosphaeriopsis sp. secreting acidic exopolymers and poor calcification of filamentous Leptolyngbya sp. secreting non-acidic exopolymers form peloids and fenestral structures, respectively, i.e. the clotted fabric of thrombolites. Based on these findings, we suggest that the rise and decline of cyanobacteria possessing different exopolymer properties caused the expansion of thrombolites around the Proterozoic/Cambrian boundary.
    Keywords Medicine ; R ; Science ; Q
    Language English
    Publishing date 2017-09-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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