Economic and Environmental Geology

Fig. 8.

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Fig. 8. Diagram showing a combination of δ13CCO2 and CDMI ([CO2/(CH4+CO2)]*100) to identify carbon dioxide origin of coalbed gases in AA-1 core samples of the Asem-Asem Basin, Indonesia. The coalbed gases of AA-1 core samples (red solid circles) were plotted abiogenic CO2 source (magmatic or mantle origin) in the genetic fields (Kotarba and Rice, 2001). The secondary CO2 (SM; blue dot line) is associated with a microbial methanogenic pathway in coalbed gases from the Ordos Basin, China (open circles, Zhang et al., 2019).
Econ. Environ. Geol. 2022;55:261-71 https://doi.org/10.9719/EEG.2022.55.3.261
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