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dc.contributor.authorKawagucci, Shinsuke  Concept link
dc.contributor.authorMiyazaki, Junichi  Concept link
dc.contributor.authorMorono, Yuki  Concept link
dc.contributor.authorSeewald, Jeffrey S.  Concept link
dc.contributor.authorWheat, C. Geoffrey  Concept link
dc.contributor.authorTakai, Ken  Concept link
dc.identifier.citationProgress in Earth and Planetary Science 5 (2018): 74en_US
dc.description© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Progress in Earth and Planetary Science 5 (2018): 74, doi:10.1186/s40645-018-0232-3.en_US
dc.description.abstractSouth Chamorro Seamount (SCS) is a blueschist-bearing serpentinite mud volcano in the Mariana forearc. Previous scientific drilling conducted at SCS revealed highly alkaline, sulfate-rich formation fluids resulting from slab-derived fluid upwelling combined with serpentinization both beneath and within the seamount. In the present study, a time-series of ROV dives spanning 1000 days was conducted to collect discharging alkaline fluids from the cased Ocean Drilling Program (ODP) Hole 1200C (hereafter the CORK fluid). The CORK fluids were analyzed for chemical compositions (including dissolved gas) and microbial community composition/function. Compared to the ODP porewater, the CORK fluids were generally identical in concentration of major ions, with the exception of significant sulfate depletion and enrichment in sulfide, alkalinity, and methane. Microbiological analyses of the CORK fluids revealed little biomass and functional activity, despite habitable temperature conditions. The post-drilling sulfate depletion is likely attributable to sulfate reduction coupled with oxidation of methane (and hydrogen), probably triggered by the drilling and casing operations. Multiple lines of evidence suggest that abiotic organic synthesis associated with serpentinization is the most plausible source of the abundant methane in the CORK fluid. The SCS formation fluid regime presented here may represent the first example on Earth where abiotic syntheses are conspicuous with little biotic processes, despite a condition with sufficient bioavailable energy potentials and temperatures within the habitable range.en_US
dc.description.sponsorshipThis work was partly supported by JSPS KAKENHI Grant Number 25701004 (SK).en_US
dc.rightsAttribution 4.0 International*
dc.subjectForearc serpentinite mud volcanoen_US
dc.subjectSouth Chamorro Seamounten_US
dc.subjectLimit of biosphereen_US
dc.subjectPresent-days’ chemical evolutionen_US
dc.subjectRadio-isotope-tracer carbon assimilation estimationen_US
dc.titleCool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamounten_US

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Attribution 4.0 International
Except where otherwise noted, this item's license is described as Attribution 4.0 International