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Extreme (13)C depletion of carbonates formed during oxidation of biogenic methane in fractured granite.

ABSTRACT: Precipitation of exceptionally 13C-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 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C (?13C 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 13C-depleted carbonates ever reported, ?13C 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.

SUBMITTER: Drake H

PROVIDER: S-EPMC4432592 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

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Extreme (13)C depletion of carbonates formed during oxidation of biogenic methane in fractured granite.

Drake Henrik H Åström Mats E ME Heim Christine C Broman Curt C Åström Jan J Whitehouse Martin M Ivarsson Magnus M Siljeström Sandra S Sjövall Peter P

Nature communications 20150507

Precipitation of exceptionally 13C-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 13C than in the source methane, because of incorporation of C also from other sources, they are far more depleted in 13C (δ13C as light as -69‰ V-PDB) than in carbonates formed where no methane is involved. Here we show that oxidation of biogenic methane in ...[more]

PMID: 25948095

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Dataset Information

Extreme (13)C depletion of carbonates formed during oxidation of biogenic methane in fractured granite.

Publications

Extreme (13)C depletion of carbonates formed during oxidation of biogenic methane in fractured granite.

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