Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions
MetadataShow full item record
The conditions of methane (CH4) formation in olivine-hosted secondary fluid inclusions and their prevalence in peridotite and gabbroic rocks from a wide range of geological settings were assessed using confocal Raman spectroscopy, optical and scanning electron microscopy, electron microprobe analysis, and thermodynamic modeling. Detailed examination of 160 samples from ultraslow- to fast-spreading midocean ridges, subduction zones, and ophiolites revealed that hydrogen (H2) and CH4 formation linked to serpentinization within olivine-hosted secondary fluid inclusions is a widespread process. Fluid inclusion contents are dominated by serpentine, brucite, and magnetite, as well as CH4(g) and H2(g) in varying proportions, consistent with serpentinization under strongly reducing, closed-system conditions. Thermodynamic constraints indicate that aqueous fluids entering the upper mantle or lower oceanic crust are trapped in olivine as secondary fluid inclusions at temperatures higher than ∼400 °C. When temperatures decrease below ∼340 °C, serpentinization of olivine lining the walls of the fluid inclusions leads to a near-quantitative consumption of trapped liquid H2O. The generation of molecular H2 through precipitation of Fe(III)-rich daughter minerals results in conditions that are conducive to the reduction of inorganic carbon and the formation of CH4. Once formed, CH4(g) and H2(g) can be stored over geological timescales until extracted by dissolution or fracturing of the olivine host. Fluid inclusions represent a widespread and significant source of abiotic CH4 and H2 in submarine and subaerial vent systems on Earth, and possibly elsewhere in the solar system.
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Proceedings of the National Academy of Sciences.of the United States of America 116(36), (2019): 17666-17672. doi:10.1073/pnas.1907871116.
The publisher requires that this item be embargoed until 2020-02-19. Please check back after 2020-02-19.
Suggested CitationKlein, F., Grozeva, N. G., & Seewald, J. S. (2019). Abiotic methane synthesis and serpentinization in olivine-hosted fluid inclusions. Proceedings of the National Academy of Sciences of the United States of America,116 (36), 17666-17672.
The following license files are associated with this item:
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International
Showing items related by title, author, creator and subject.
Fluid inclusion evidence for subsurface phase separation and variable fluid mixing regimes beneath the deep-sea PACMANUS hydrothermal field, Manus Basin back arc rift, Papua New Guinea Vanko, David A.; Bach, Wolfgang; Roberts, Stephen; Yeats, Christopher J.; Scott, Steven D. (American Geophysical Union, 2004-03-05)Altered volcanic rocks were cored from over 350 m below the seafloor at the Papua New Guinea-Australia-Canada Manus Basin Hydrothermal Field (PACMANUS) deep-sea hydrothermal field, in the eastern Manus back arc basin. Fluid ...
Cool, alkaline serpentinite formation fluid regime with scarce microbial habitability and possible abiotic synthesis beneath the South Chamorro Seamount Kawagucci, Shinsuke; Miyazaki, Junichi; Morono, Yuki; Seewald, Jeffrey S.; Wheat, C. Geoffrey; Takai, Ken (Springer, 2018-11-14)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 ...
Wave scattering from cylindrical fluid inclusions in an elastic medium and determination of effective medium properties Laible, Henry A. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1995-09)The goal of this thesis is to be able to predict acoustic wave speeds in sea ice with known concentrations of inhomogeneities. To accomplish this, ice is modeled as a solid in which cylindrical fluid brine channels are ...