Anaerobic oxidation of methane by Mn oxides in sulfate-poor environments

Chunfang Cai; Kaikai Li; Dawei Liu; Cedric M. John; Daowei Wang; Bin Fu; Mojtaba Fakhraee; Hong He; Lianjun Feng; Lei Jiang

doi:10.1130/G48553.1

Anaerobic oxidation of methane by Mn oxides in sulfate-poor environments

Chunfang Cai^*, Kaikai Li, Dawei Liu, Cedric M. John, Daowei Wang, Bin Fu, Mojtaba Fakhraee, Hong He, Lianjun Feng, Lei Jiang

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

33 Citations (Scopus)

Abstract

Strongly 13C-depleted authigenic carbonates (e.g., δ¹³CVPDB < −30‰; VPDB—Vienna Peedee belemnite) in nature are generally believed to form by sulfate-dependent anaerobic oxidation of methane (AOM). However, we demonstrate using geochemical data and thermodynamic calculation that such calcites are most likely derived from biogenic oxidation of methane insulfate-poor, nonmarine environments during early diagenesis, as observed in the Triassic sandy conglomerates from the Junggar Basin, northwestern China. This process operated through preferential oxidation of ¹³C-depleted methane by Mn oxides in closed conditions, producing calcites with higher Mn contents and δ¹³C values in association with more ¹³C-enriched residual methane as a result of kinetic isotope fractionation. Thus, the Mn-rich and ¹³C-depleted carbonates are proposed as tracers of Mn-dependent AOM, which should have served as an important sink of greenhouse methane in low-sulfate early Earth’s oceans.

Original language	English
Pages (from-to)	761-766
Number of pages	6
Journal	Geology
Volume	49
Issue number	7
DOIs	https://doi.org/10.1130/G48553.1
Publication status	Published - Jul 2021

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title = "Anaerobic oxidation of methane by Mn oxides in sulfate-poor environments",

abstract = "Strongly 13C-depleted authigenic carbonates (e.g., δ13CVPDB < −30‰; VPDB—Vienna Peedee belemnite) in nature are generally believed to form by sulfate-dependent anaerobic oxidation of methane (AOM). However, we demonstrate using geochemical data and thermodynamic calculation that such calcites are most likely derived from biogenic oxidation of methane insulfate-poor, nonmarine environments during early diagenesis, as observed in the Triassic sandy conglomerates from the Junggar Basin, northwestern China. This process operated through preferential oxidation of 13C-depleted methane by Mn oxides in closed conditions, producing calcites with higher Mn contents and δ13C values in association with more 13C-enriched residual methane as a result of kinetic isotope fractionation. Thus, the Mn-rich and 13C-depleted carbonates are proposed as tracers of Mn-dependent AOM, which should have served as an important sink of greenhouse methane in low-sulfate early Earth{\textquoteright}s oceans.",

author = "Chunfang Cai and Kaikai Li and Dawei Liu and John, {Cedric M.} and Daowei Wang and Bin Fu and Mojtaba Fakhraee and Hong He and Lianjun Feng and Lei Jiang",

note = "Publisher Copyright: {\textcopyright} 2021 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license.",

year = "2021",

month = jul,

doi = "10.1130/G48553.1",

language = "English",

volume = "49",

pages = "761--766",

journal = "Geology",

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T1 - Anaerobic oxidation of methane by Mn oxides in sulfate-poor environments

AU - Cai, Chunfang

AU - Li, Kaikai

AU - Liu, Dawei

AU - John, Cedric M.

AU - Wang, Daowei

AU - Fu, Bin

AU - Fakhraee, Mojtaba

AU - He, Hong

AU - Feng, Lianjun

AU - Jiang, Lei

PY - 2021/7

Y1 - 2021/7

N2 - Strongly 13C-depleted authigenic carbonates (e.g., δ13CVPDB < −30‰; VPDB—Vienna Peedee belemnite) in nature are generally believed to form by sulfate-dependent anaerobic oxidation of methane (AOM). However, we demonstrate using geochemical data and thermodynamic calculation that such calcites are most likely derived from biogenic oxidation of methane insulfate-poor, nonmarine environments during early diagenesis, as observed in the Triassic sandy conglomerates from the Junggar Basin, northwestern China. This process operated through preferential oxidation of 13C-depleted methane by Mn oxides in closed conditions, producing calcites with higher Mn contents and δ13C values in association with more 13C-enriched residual methane as a result of kinetic isotope fractionation. Thus, the Mn-rich and 13C-depleted carbonates are proposed as tracers of Mn-dependent AOM, which should have served as an important sink of greenhouse methane in low-sulfate early Earth’s oceans.

AB - Strongly 13C-depleted authigenic carbonates (e.g., δ13CVPDB < −30‰; VPDB—Vienna Peedee belemnite) in nature are generally believed to form by sulfate-dependent anaerobic oxidation of methane (AOM). However, we demonstrate using geochemical data and thermodynamic calculation that such calcites are most likely derived from biogenic oxidation of methane insulfate-poor, nonmarine environments during early diagenesis, as observed in the Triassic sandy conglomerates from the Junggar Basin, northwestern China. This process operated through preferential oxidation of 13C-depleted methane by Mn oxides in closed conditions, producing calcites with higher Mn contents and δ13C values in association with more 13C-enriched residual methane as a result of kinetic isotope fractionation. Thus, the Mn-rich and 13C-depleted carbonates are proposed as tracers of Mn-dependent AOM, which should have served as an important sink of greenhouse methane in low-sulfate early Earth’s oceans.

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U2 - 10.1130/G48553.1

DO - 10.1130/G48553.1

M3 - Article

SN - 0091-7613

VL - 49

SP - 761

EP - 766

JO - Geology

JF - Geology

IS - 7

ER -

Anaerobic oxidation of methane by Mn oxides in sulfate-poor environments

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