85-2 Assessing the Potential of Fluid Inclusion Degassing by Chemical and Mechanical Alteration of Exposed Rocks.

Session: The Power of Hard Rocks: Driving the Energy Transition and Serving Society

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Quantifying geological fluxes of greenhouse gases into the atmosphere has been a subject of interest in the past decades to better understand present day climate change. Efforts to address the role of deep Earth processes in the global carbon cycle have mostly focused on estimating deep carbon sources and sinks in the Earth's crust and mantle, yet greenhouse gas emission contributions from exposed metamorphic rocks remain widely unconstrained. Here we present a preliminary assessment of greenhouse gases in fluid inclusions that are released by the mechanical and chemical alteration of exhumed metasedimentary rocks with the goal of quantifying CO₂ and CH₄ emission potential into the atmosphere.  

Preliminary CH₄ and CO₂ concentrations measured by bulk gas extraction analysis suggest that concordant quartz veins in metapelites have higher potential for fluid inclusion degassing when compared to their host rock. Emission potential estimates in veins were as high as 7.40 X 10⁷ tons of CH₄ per km³ of rock and 1.70 X 10⁷ tons of CO₂ per km³ of rock, while the host rocks yield CH₄ and CO₂ estimates three to four orders of magnitude less. Our dataset, even if preliminary, provides an important starting point for the assessment of the global scale contribution of fluid inclusion decrepitation to geologic greenhouse gas emissions. 

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10455

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