Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount
Abstract South 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 beneat...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2018-11-01
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| Series: | Progress in Earth and Planetary Science |
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| Online Access: | http://link.springer.com/article/10.1186/s40645-018-0232-3 |
| _version_ | 1818532360444968960 |
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| author | Shinsuke Kawagucci Junichi Miyazaki Yuki Morono Jeff S. Seewald C. Geoff Wheat Ken Takai |
| author_facet | Shinsuke Kawagucci Junichi Miyazaki Yuki Morono Jeff S. Seewald C. Geoff Wheat Ken Takai |
| author_sort | Shinsuke Kawagucci |
| collection | DOAJ |
| description | Abstract South 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. |
| first_indexed | 2024-12-11T17:44:29Z |
| format | Article |
| id | doaj.art-31214fea0ebf4158843ba82a338c936c |
| institution | Directory Open Access Journal |
| issn | 2197-4284 |
| language | English |
| last_indexed | 2024-12-11T17:44:29Z |
| publishDate | 2018-11-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Progress in Earth and Planetary Science |
| spelling | doaj.art-31214fea0ebf4158843ba82a338c936c2022-12-22T00:56:26ZengSpringerOpenProgress in Earth and Planetary Science2197-42842018-11-015112010.1186/s40645-018-0232-3Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro SeamountShinsuke Kawagucci0Junichi Miyazaki1Yuki Morono2Jeff S. Seewald3C. Geoff Wheat4Ken Takai5Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)Department of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC)Department Marine Chemistry and Geochemistry (MC&G), Woods Hole Oceanographic Institution (WHOI)Global Undersea Research Unit, University of Alaska FairbanksDepartment of Subsurface Geobiological Analysis and Research (D-SUGAR), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)Abstract South 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.http://link.springer.com/article/10.1186/s40645-018-0232-3Forearc serpentinite mud volcanoSouth Chamorro SeamountLimit of biospherePresent-days’ chemical evolutionRadio-isotope-tracer carbon assimilation estimation |
| spellingShingle | Shinsuke Kawagucci Junichi Miyazaki Yuki Morono Jeff S. Seewald C. Geoff Wheat Ken Takai Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount Progress in Earth and Planetary Science Forearc serpentinite mud volcano South Chamorro Seamount Limit of biosphere Present-days’ chemical evolution Radio-isotope-tracer carbon assimilation estimation |
| title | Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount |
| title_full | Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount |
| title_fullStr | Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount |
| title_full_unstemmed | Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount |
| title_short | Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount |
| title_sort | cool alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the south chamorro seamount |
| topic | Forearc serpentinite mud volcano South Chamorro Seamount Limit of biosphere Present-days’ chemical evolution Radio-isotope-tracer carbon assimilation estimation |
| url | http://link.springer.com/article/10.1186/s40645-018-0232-3 |
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