Please use this identifier to cite or link to this item:
http://hdl.handle.net/2122/16207
Authors: | Etiope, Giuseppe* Oze, Christopher* |
Title: | Microbial vs abiotic origin of methane in continental serpentinized ultramafic rocks: A critical review and the need of a holistic approach | Journal: | Applied Geochemistry | Series/Report no.: | /143 (2022) | Publisher: | Elsevier | Issue Date: | 2022 | DOI: | 10.1016/j.apgeochem.2022.105373 | Abstract: | Continental ultramafic rock systems, through the process of serpentinization, provide chemical and biochemical pathways that lead to the production of methane. The extent to which rock-water-gas reactions and organisms supply methane in these systems is a matter of considerable discussion and debate. Deciphering the interplay of abiotic and microbial methane observed at the surface requires several lines of reasoning as well as a variety of analyses. Despite using multiple models and interpretative tools, conclusions for the origin of methane at a particular site may vary or diverge from regional or global observations. Here, we critically address how possible conclusions of microbial versus abiotic methane in continental serpentinization systems may be interpreted and reinterpreted. We review fundamental concepts, advantages and limits, for three major methane origin models: (a) abiotic CO2 hydrogenation supplying gas reservoirs, (b) derivation from fluid inclusions in olivine-rich rocks, and (c) microbialgenesis in aquifers. We use the case of methane in the Samail ophiolite of Oman as an emblematic example of multiple interpretations; we identify ambiguous information offered by methane clumped isotopes and molecular gas compositions (e.g., the meaning of gaseous hydrocarbons heavier than methane), and suggest key tools, such as radiocarbon (14C) in methane, which may solve interpretative issues. The major constraint in any model of methane origin is the capability to sustain continuous gas flows, in terms of methane emission intensity, longevity and spatial extension, such as in natural gas sedimentary systems. Overall, this review suggests that any site interpretation can benefit from a holistic approach, integrating geochemical, geological and biological data with gas flow dynamics, as well as including regional and global contextualization. |
Appears in Collections: | Article published / in press |
Files in This Item:
File | Description | Size | Format | Existing users please Login |
---|---|---|---|---|
Etiope and Oze 2022 AppGeo review.pdf | Restricted Paper | 5.25 MB | Adobe PDF | |
Etiope-Oze 2022 accepted version.pdf | Final accepted version | 4.37 MB | Adobe PDF | Embargoed until June 1, 2024 |
Etiope and Oze 2022 AppGeo SUPPLEM.pdf | Supplementary Material | 1.94 MB | Adobe PDF | Embargoed until June 1, 2024 |
Page view(s)
46
checked on Apr 24, 2024
Download(s)
5
checked on Apr 24, 2024