Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

Wen Xuan Hu; Xun Kang; Jian Cao; Xiao Lin Wang; Bin Fu; Hai Guang Wu

doi:10.1038/s41467-018-07267-x

Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

Wen Xuan Hu^*, Xun Kang, Jian Cao, Xiao Lin Wang, Bin Fu, Hai Guang Wu

^*Corresponding author for this work

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

62 Citations (Scopus)

Abstract

Thermochemical oxidation of methane (TOM) by high-valence metal oxides in geological systems and its potential role as a methane sink remain poorly understood. Here we present evidence of TOM induced by high-valence metal oxides in the Junggar Basin, located in northwestern China. During diagenesis, methane from deeper source strata is abiotically oxidized by high-valence Mn(Fe) oxides at 90 to 135 °C, releasing ¹³C-depleted CO₂, soluble Mn²⁺ and Fe²⁺. Mn generally plays the dominant role compared to Fe, due to its lower Gibbs free energy increment during oxidation. Both CO₂ and metal ions are then incorporated into authigenic calcites, which are characterized by extremely negative δ¹³C values (−70 to −22.5‰) and high Mn content (average MnO = 5 wt.%). We estimate that as much as 1224 Tg of methane could be oxidized in the study area. TOM is unfavorable for gas accumulation but may act as a major methane sink in the deep crustal carbon cycle.

Original language	English
Article number	5131
Journal	Nature Communications
Volume	9
Issue number	1
DOIs	https://doi.org/10.1038/s41467-018-07267-x
Publication status	Published - 1 Dec 2018

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title = "Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin",

abstract = "Thermochemical oxidation of methane (TOM) by high-valence metal oxides in geological systems and its potential role as a methane sink remain poorly understood. Here we present evidence of TOM induced by high-valence metal oxides in the Junggar Basin, located in northwestern China. During diagenesis, methane from deeper source strata is abiotically oxidized by high-valence Mn(Fe) oxides at 90 to 135 °C, releasing 13C-depleted CO2, soluble Mn2+ and Fe2+. Mn generally plays the dominant role compared to Fe, due to its lower Gibbs free energy increment during oxidation. Both CO2 and metal ions are then incorporated into authigenic calcites, which are characterized by extremely negative δ13C values (−70 to −22.5‰) and high Mn content (average MnO = 5 wt.%). We estimate that as much as 1224 Tg of methane could be oxidized in the study area. TOM is unfavorable for gas accumulation but may act as a major methane sink in the deep crustal carbon cycle.",

author = "Hu, {Wen Xuan} and Xun Kang and Jian Cao and Wang, {Xiao Lin} and Bin Fu and Wu, {Hai Guang}",

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T1 - Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

AU - Hu, Wen Xuan

AU - Kang, Xun

AU - Cao, Jian

AU - Wang, Xiao Lin

AU - Fu, Bin

AU - Wu, Hai Guang

PY - 2018/12/1

Y1 - 2018/12/1

N2 - Thermochemical oxidation of methane (TOM) by high-valence metal oxides in geological systems and its potential role as a methane sink remain poorly understood. Here we present evidence of TOM induced by high-valence metal oxides in the Junggar Basin, located in northwestern China. During diagenesis, methane from deeper source strata is abiotically oxidized by high-valence Mn(Fe) oxides at 90 to 135 °C, releasing 13C-depleted CO2, soluble Mn2+ and Fe2+. Mn generally plays the dominant role compared to Fe, due to its lower Gibbs free energy increment during oxidation. Both CO2 and metal ions are then incorporated into authigenic calcites, which are characterized by extremely negative δ13C values (−70 to −22.5‰) and high Mn content (average MnO = 5 wt.%). We estimate that as much as 1224 Tg of methane could be oxidized in the study area. TOM is unfavorable for gas accumulation but may act as a major methane sink in the deep crustal carbon cycle.

AB - Thermochemical oxidation of methane (TOM) by high-valence metal oxides in geological systems and its potential role as a methane sink remain poorly understood. Here we present evidence of TOM induced by high-valence metal oxides in the Junggar Basin, located in northwestern China. During diagenesis, methane from deeper source strata is abiotically oxidized by high-valence Mn(Fe) oxides at 90 to 135 °C, releasing 13C-depleted CO2, soluble Mn2+ and Fe2+. Mn generally plays the dominant role compared to Fe, due to its lower Gibbs free energy increment during oxidation. Both CO2 and metal ions are then incorporated into authigenic calcites, which are characterized by extremely negative δ13C values (−70 to −22.5‰) and high Mn content (average MnO = 5 wt.%). We estimate that as much as 1224 Tg of methane could be oxidized in the study area. TOM is unfavorable for gas accumulation but may act as a major methane sink in the deep crustal carbon cycle.

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Thermochemical oxidation of methane induced by high-valence metal oxides in a sedimentary basin

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