Orogenic degassing is emerging as a potentially relevant source of carbon dioxide (CO2) from the continental crust. However, the processes of carbon mobilization are still poorly explored. Here, we use thermodynamic modeling to investigate the decarbonation of sediments metamorphosed under high geothermal gradients. Our modeling shows that immiscible CO2-rich vapors and hydrosaline brines are generated at these conditions, with different properties and mobility through the crust. The CO2-rich fluid fraction could rapidly rise toward the surface without interacting with the host rocks by carbo-fracturing the host rocks or through deep faults. The denser hydrosaline brines likely permeate the source rocks. When applied to the active Himalayan orogen, these observations reconcile measured CO2 fluxes at the surface and positive conductivity anomalies associated with micro-seismicity at depth. Our modeling shows that the continental crust represents a relevant reservoir of CO2 that can be efficiently degassed during hot collisions.

Groppo, C., Rolfo, F., Frezzotti, M. (2022). CO2 outgassing during collisional orogeny is facilitated by the generation of immiscible fluids. COMMUNICATIONS EARTH & ENVIRONMENT, 3(1), 1-11 [10.1038/s43247-022-00340-w].

CO2 outgassing during collisional orogeny is facilitated by the generation of immiscible fluids

Frezzotti, ML
2022

Abstract

Orogenic degassing is emerging as a potentially relevant source of carbon dioxide (CO2) from the continental crust. However, the processes of carbon mobilization are still poorly explored. Here, we use thermodynamic modeling to investigate the decarbonation of sediments metamorphosed under high geothermal gradients. Our modeling shows that immiscible CO2-rich vapors and hydrosaline brines are generated at these conditions, with different properties and mobility through the crust. The CO2-rich fluid fraction could rapidly rise toward the surface without interacting with the host rocks by carbo-fracturing the host rocks or through deep faults. The denser hydrosaline brines likely permeate the source rocks. When applied to the active Himalayan orogen, these observations reconcile measured CO2 fluxes at the surface and positive conductivity anomalies associated with micro-seismicity at depth. Our modeling shows that the continental crust represents a relevant reservoir of CO2 that can be efficiently degassed during hot collisions.
Articolo in rivista - Articolo scientifico
CO2; collisional orogens; Himalaya; metamorphic rocks; decarbonation reactions;
English
18-gen-2022
2022
3
1
1
11
13
open
Groppo, C., Rolfo, F., Frezzotti, M. (2022). CO2 outgassing during collisional orogeny is facilitated by the generation of immiscible fluids. COMMUNICATIONS EARTH & ENVIRONMENT, 3(1), 1-11 [10.1038/s43247-022-00340-w].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/346365
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