300-Myr-old magmatic CO2 in natural gas reservoirs of the west Texas Permian basin
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Summary
This summary is machine-generated.Magmatic carbon dioxide (CO2) from degassing magma bodies, not just crustal sources, explains gas compositions in sedimentary basins. This finding suggests a re-evaluation of CO2 origins in many mid-continent basins.
Area Of Science
- Geochemistry
- Sedimentary geology
- Tectonics
Background
- Traditionally, carbon dioxide (CO2) in sedimentary basins is attributed to crustal organic matter or mineral reactions.
- This study challenges this assumption by proposing an alternative origin for CO2.
Purpose Of The Study
- To investigate the origin of CO2 in CO2-rich natural gases in the west Texas Val Verde basin.
- To explain observed CO2/3He ratios, delta13C(CO2) values, and mantle 3He/22Ne ratios in basin systems.
- To re-evaluate the origin of CO2 in mid-continent basin systems.
Main Methods
- Analysis of CO2/3He ratios and delta13C(CO2) values in natural gases.
- Application of Rayleigh fractionation models to explain magma degassing.
- Correlation of tectonic events with gas composition data.
Main Results
- Rayleigh fractionation from partial magma degassing explains CO2/3He and delta13C(CO2) values in the Val Verde basin.
- Mantle 3He/22Ne ratios in other basin systems are also consistent with magmatic CO2.
- CO2 input predates methane generation (approx. 280 Myr ago), with uplift (310-280 Myr ago) as the likely magmatic source.
- Natural gas preservation in traps exceeds 300 Myr, longer than predicted by diffusion models.
Conclusions
- Magmatic CO2 is a significant source in foreland basins, necessitating a re-evaluation of CO2 origins in other basins.
- The long-term preservation of natural gas challenges existing diffusion models.