Extreme C-13 depletion of carbonates formed during oxidation of biogenic methane in fractured granite
2015 | journal article. A publication with affiliation to the University of Göttingen.
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Extreme C-13 depletion of carbonates formed during oxidation of biogenic methane in fractured granite
Drake, H.; Astrom, M. E.; Heim, C. ; Broman, C.; Astrom, J.; Whitehouse, M. J. & Ivarsson, M. et al. (2015)
Nature Communications, 6 art. 7020. DOI: https://doi.org/10.1038/ncomms8020
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Details
- Authors
- Drake, Henrik; Astrom, Mats E.; Heim, Christine ; Broman, Curt; Astrom, Jan; Whitehouse, Martin J.; Ivarsson, Magnus; Siljestrom, Sandra; Sjovall, Peter
- Abstract
- Precipitation of exceptionally C-13-depleted authigenic carbonate is a result of, and thus a tracer for, sulphate-dependent anaerobic methane oxidation, particularly in marine sediments. Although these carbonates typically are less depleted in C-13 than in the source methane, because of incorporation of C also from other sources, they are far more depleted in C-13 (delta C-13 as light as - 69% V-PDB) than in carbonates formed where no methane is involved. Here we show that oxidation of biogenic methane in carbon-poor deep groundwater in fractured granitoid rocks has resulted in fracture-wall precipitation of the most extremely C-13-depleted carbonates ever reported, delta C-13 down to - 125% V-PDB. A microbial consortium of sulphate reducers and methane oxidizers has been involved, as revealed by biomarker signatures in the carbonates and S-isotope compositions of co-genetic sulphide. Methane formed at shallow depths has been oxidized at several hundred metres depth at the transition to a deep-seated sulphate-rich saline water. This process is so far an unrecognized terrestrial sink of methane.
- Issue Date
- 2015
- Journal
- Nature Communications
- ISSN
- 2041-1723