Authors / CoAuthors
Boreham, C. | Davies, J.
Abstract
The <sup>60</sup>Co gamma ray radiolysis of methane was undertaken at room temperature and at a low proportion of methane conversion to observe initial polymerisation reactions in the formation of C<sub>2</sub>─C<sub>5</sub> saturated hydrocarbon gases. The gamma ray radiolysis product follows a Schulz-Flory distribution model for the straight-chained C2+ alkane gases consistent with chain propagation by addition of C<sub>1</sub> intermediates. The high relative concentration of branched isomers suggests the total product distribution is likely controlled by propagation reactions involving mainly radical intermediates. In particular, the pentane isomers show a relative dominance of the branched isomers with sub-equal amounts of iso-pentane and neo-pentane. Carbon isotopes of the C<sub>2</sub>─C<sub>5</sub> wet gases are all depleted in 13C relative to δ13C methane reactant with δ<sup>13</sup>C C<sub>2</sub> < δ<sup>13</sup>C C<sub>3</sub> and carbon isotope reversals in the C<sub>3</sub>─C<sub>5</sub> gases while only ethane and neo-pentane are depleted in <sup>2</sup>H compared to δ<sup>2</sup>H of the starting methane. As such, these molecular and isotopic features show similar characteristics to abiogenic wet gases found in terrestrial settings. Bibliographic Citation: Boreham, C. J., & Davies, J. B. (2020). Carbon and hydrogen isotopes of the wet gases produced by gamma-ray-induced polymerisation of methane: Insights into radiogenic mechanism and natural gas formation. Radiation Physics and Chemistry, 168, 108546. https://doi.org/10.1016/j.radphyschem.2019.108546
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document
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112184
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Keywords
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- Abiogenic hydrocarbons
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- gamma radiolysi
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- methane
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- Australian natural gas
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- carbon and hydrogen isotope reversal
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- neo-pentane
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- helium
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- Published_External
Publication Date
2025-01-09T00:50:45
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2017-07-31T00:00:00
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geoscientificInformation
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Radiation Physics and Chemistry Volume 168, March 2020, Article 108546
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External publication prepared for submission to the Radiation Physics and Chemistry journal on ScienceDirect
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[-52.00, -9.00, 112.00, 154.00]
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