The importance of carbonatite lavas in outgassing Venus' modern-day atmosphere.

Venus diverged from Earth's evolutionary path through the development of a carbon dioxide (CO2)-dominated atmosphere, although studies dispute whether this atmosphere arose shortly after accretion or after a protracted period of surface habitability. Widespread volcanic features suggest that volcanic outgassing may have played a pivotal role in the transformation of Venus. However, the formation of volcanic units on Venus by basaltic lavas can only outgas a minor fraction of the CO2 in the current atmosphere. Here, we model the erosion of long, meandering channels on Venus called canali and show that carbonatite lavas have the unique properties required to erode the canali. Our results suggest that eruption of these carbonatites may have delivered a total mass of CO2 comparable to that of the modern atmosphere, resolving challenges to the formation of Venus' atmosphere within the recent past and suggesting that exoplanets in the "Venus zone" may exhibit the potential for prolonged habitability.