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Low silica activity for hydrogen generation during serpentinization: An example of natural serpentinites in the Mineoka ophiolite complex, central Japan
- Source :
- Earth and Planetary Science Letters. 298(1-2):199-204
- Publication Year :
- 2010
- Publisher :
- Elsevier Science BV, 2010.
-
Abstract
- The textural evolution in the serpentinite of the Mineoka ophiolite complex has been investigated to constrain the natural environment for hydrogen production in the serpentinite-hosted hydrothermal vent systems. Textural relations of the serpentinites from the Mineoka ophiolite indicate at least two stages in the process of serpentinization, with the replacement of olivine by a mesh texture of serpentine and brucite, followed by the development of magnetite-bearing or -free serpentine veins. The generation of hydrogen during serpentinization, which accompanies the formation of magnetite, involves a silica-depletion reaction, as evidenced by the low abundance of serpentine in the magnetite-bearing veins and the absence of magnetite in pseudomorphs of orthopyroxene. Direct evidence for the production of hydrogen and strongly reducing conditions is provided by CH4 and H-2-bearing inclusions in relic olivine crystals; the production of methane and hydrogen may have provided a suitable environment for microbial activity in hydrothermal vent systems along the seafloor. Our results indicate that low silica activity plays a key role in the generation of hydrogen during serpentinization, and that low silica activity environments are possible in olivine-rich rocks such as dunite, or during local disequilibrium in other silica-poor rocks in the mantle lithosphere.
- Subjects :
- magnetite
Hydrogen
Geochemistry
chemistry.chemical_element
engineering.material
Ophiolite
Mantle (geology)
silica activity
chemistry.chemical_compound
serpentinite
Geochemistry and Petrology
Earth and Planetary Sciences (miscellaneous)
Magnetite
Olivine
Brucite
Geophysics
hydrothermal vent system
chemistry
Space and Planetary Science
hydrogen
engineering
microbial community
Pseudomorph
Geology
Hydrothermal vent
Subjects
Details
- Language :
- English
- ISSN :
- 0012821X
- Volume :
- 298
- Issue :
- 1-2
- Database :
- OpenAIRE
- Journal :
- Earth and Planetary Science Letters
- Accession number :
- edsair.doi.dedup.....220b90118799905d58f240b6d500938c