Modeling Cryptic Degassing From Intrusive Magmatism on Venus

Cryptic degassing is the release of volatiles from a magmatic intrusion independent of extrusive volcanic activity. On Earth, rheological transitions within the crust can throttle magma ascent, leading to the cryptic release of volatiles and the decoupling of the CO₂ flux from the rate of extrusive volcanism (Black et al., 2024). This process is particularly significant for large igneous province (LIP) events, where high magma influx rates may sustain CO₂ release and lead to greenhouse warming for > 1 Myr after eruption ceases (Black et al., 2024).

On Venus, higher surface temperatures and lower eruption efficiencies (Lourenço et al., 2020) suggest that this rheologic transition can occur for even lower magmatic influx rates than on Earth. Venus’s surface exhibits numerous volcanic features associated with intrusive magmatism, including coronae and steep-sided domes, where shallow intrusions may continuously outgas volatiles to the atmosphere. However, the role of cryptic degassing on Venus and its potential for influencing the atmosphere has not been previously explored.

We will present a model of rheologic throttling of magmas within Venus’s crust and assess the potential for cryptic degassing of CO₂ and other volatiles. Our results will have implications for understanding how outgassing has contributed to Venus’s atmosphere and the interpretation of noble gas signatures such as argon and helium isotopes (Namiki & Solomon, 1998).

References

Black, B. A., Karlstrom, L., Mills, B. J. W., Mather, T. A., Rudolph, M. L., Longman, J., & Merdith, A. (2024). Cryptic degassing and protracted greenhouse climates after flood basalt events. Nature Geoscience, 17(11), 1162–1168. https://doi.org/10.1038/s41561-024-01574-3

Lourenço, D. L., Rozel, A. B., Ballmer, M. D., & Tackley, P. J. (2020). Plutonic-Squishy Lid: A New Global Tectonic Regime Generated by Intrusive Magmatism on Earth-Like Planets. Geochemistry, Geophysics, Geosystems, 21(4), e2019GC008756. https://doi.org/10.1029/2019GC008756

Namiki, N., & Solomon, S. C. (1998). Volcanic degassing of argon and helium and the history of crustal production on Venus. Journal of Geophysical Research: Planets, 103(E2), 3655–3677. https://doi.org/10.1029/97JE03032