[X] My Assistant

[Guest_AlexBlackwell_*]

Mineral discovery explains Mars’ landscape
Queen's University
Friday, October 20, 2006

This refers to the following paper:

Crystal molds on Mars: Melting of a possible new mineral species to create Martian chaotic terrain
Ronald C. Peterson and Ruiyao Wang
Geology, In Press (2006)

For what it's worth, Ron Peterson sent me a preprint of this paper about a month ago; it's fairly interesting.

[CosmicRocker]

Alex: When I first read the news summaries of this, I thought, this is crazy. What could have caused this mineral to melt? But I read the pdf today and I must say, it is an intriguing idea. I thought I'd add a very brief summary for people who might have wanted more detail. I chased the pdf down, and for some reason was able to get it this morning from a link at the Queens University Dept. of Geological Sciences and Geological Engineering page, but it is now only linking to the abstract. Their press release mentions that the pdf is available on request, so perhaps an email to the right person could provide it.

This new sulfate mineral, which was grown in a petri dish in a cold Ontario garage, is a highly hydrated form of magnesium sulfate identified as MgSO4*11H2O. Above 2 degrees C it melts incongruently into a MgSO4 solution and epsomite needles. The mineral appears to have a very low heat of fusion, so the melting can occur rapidly with a small heat input, as compared to water ice.

The incongruent melting generates a relatively large amount of solution and a smaller volume of solids. They suggest that the melting of this triclinic mineral could explain the platy vugs observed in the sediment at places like Guadalupe at Eagle Crater. What I find fascinating about this is the way it could explain the chaotic terain, outflow channels, etc...if this mineral was at one time abundant in Martian rocks. As they suggest, a moderate rise in the geothermal (what's it called on Mars...areothermal?) gradient could trigger a significant release of fluid and a similar rock volume reduction.

I am sure my brief summary missed some important points made by the authors, but that is my quick take on it. I haven't heard the word used much recently, but this almost sounds like a serendipitous discovery. I'd really like to know what the Ontario garage experiment originally was trying to test. Did they suspect that such a mineral could exist? I am fascinated.

[ngunn]

The mineral appears to have a very low heat of fusion, so the melting can occur rapidly with a small heat input, as compared to water ice.

A meteorite impact would presumably do the trick. Could this account for some unusual crater shapes?

[CosmicRocker]

That definitely seems possible. I'd suspect that the larger the crater, the more far-reaching the effects might be. For very large impacts, there might even be regional effects that extend well beyond the crater.

Although I never cease to be amazed by the ground truth from the rovers, and the ever better orbital views, the things that I see that seem not to fit into my terrestrial experience are those that most fascinate me. On a planetary scale, the chaotic regions related to the chasms really fascinate me, because I don't really feel confident in previous explanations for them. This recently discovered mineral seems to have properties that could be used to explain some of the things we see.