Title: An alternate mineral alteration pathway on Early Mars: Water-Saturated Liquid CO2 (wsLCO2)

Abstract: While the concept of a warm, wet early Mars is widely accepted, such acceptance is in the face of longstanding difficulty to explain how early Mars under a faint sun could have been warm enough to sustain such an extensive reservoir of liquid water. Past researchers have on occasion raised the alternate possibility that eruption of liquid CO2 from the martian subsurface could have been responsible for some of Mars' diverse morphological features. Indeed, those researchers need not have confined themselves to subsurface eruptions, as the early Mars atmosphere may well have been dense enough and cold enough to sustain liquid CO2 on the surface in the form of rain, rivers, and ponds. But ultimately, unless an alternative scenario can be found to explain the widespread evidence of aqueous mineral alteration, it is difficult to argue against the warm and wet hypothesis. The new idea to be discussed today is that when saturated with water, as would have been likely in that context, liquid CO2 s also a potent mineral alteration medium — a surprising result that has emerged from research in an entirely different discipline, the study of carbon sequestration for climate mitigation. We will discuss how wsLCO2 might explain some observations on Mars as well or better than the present aqueous alteration models, and touch on the laboratory work that would need to be done to test this hypothesis.

About this Series: The MIT Planetary Lunch Seminar [PLS] is a weekly seminar series organized within the EAPS department. Colloquia topics span the range of research interests of the department's planetary sciences research program. The seminars take place on Tuesdays from 12:15–1:30 pm, unless otherwise noted (term-time only). Speakers include members of the MIT community and visitors. Talks are intended to appeal to graduate students, postdocs, research scientists, and faculty with a background in planetary science. For more information and Zoom password contact: planetary-org@mit.edu.