BIO Web of Conferences
Volume 2, 2014EPOV 2012: From Planets to Life – Colloquium of the CNRS Interdisciplinary Initiative “Planetary Environments and Origins of Life”
|Number of page(s)||4|
|Published online||18 February 2014|
CO2-SO2 clathrate hydrate formation on early Mars
1 Univ Paris-Sud, UMR IDES, Université Paris-Sud & CNRS, Bât. 504, Orsay, F-91405, France
2 IAS, Université Paris-Sud, CNRS, France
3 Centre SPIN, ENS des Mines de Saint-Etienne, France
4 Center for Earth System Sciences, Tsinghua University, Beijing, China
5 Institut UTINAM, East-Lansing, UMR 6213, Université de Franche-Comté, France
6 Université de Toulouse; UPS-OMP; CNRS-INSU; IRAP; Toulouse, France
Most sulfate minerals discovered on Mars are dated no earlier than the Hesperian. We showed, using a 1-D radiative-convective-photochemical model, that clathrate formation during the Noachian would have buffered the atmospheric CO2 pressure of early Mars at ~2 bar and maintained a global average surface temperature ~230 K. Because clathrates trap SO2 more favorably than CO2, all volcanically outgassed sulfur would have been trapped in Noachian Mars cryosphere, preventing a significant formation of sulfate minerals during the Noachian and inhibiting carbonates from forming at the surface in acidic water resulting from the local melting of the SO2- rich cryosphere. The massive formation of sulfate minerals at the surface of Mars during the Hesperian could be the consequence of a drop of the CO2 pressure below a 2-bar threshold value at the late Noachian-Hesperian transition, which would have released sulfur gases into the atmosphere from both the Noachian sulfur-rich cryosphere and still active Tharsis volcanism. Our hypothesis could allow to explain the formation of chaotic terrains and outflow channels, and the occurrence of episodic warm episodes facilitated by the release of SO2 to the atmosphere. These episodes could explain the formation of valley networks and the degradation of impact craters, but remain to be confirmed by further modeling.
© Owned by the authors, published by EDP Sciences, 2014
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