[X] My Assistant

[dvandorn]

This is more of a general question/comment about Martian geology, but since Oppy is in such a unique environment (unlike any of the other landing sites we've visited), I figure it belongs here more than anywhere else.

As far as I've been able to tell in my reading of the results of the various Mars probes, there doesn't seem to be much in the way of granite on the surface of Mars. There's a lot of basaltic and andesitic lava-rock (with a lot of olivine, pyroxene and even ilmenite), some ancient feldspathic/anorthositic rock, a lot of sulfates and other salts, a lot of rusted iron -- but little to no granite.

There's almost no granite in any of the lunar samples, either. Quartz also seems to be very rare, both in lunar samples and in what we see on Mars.

Has anyone here heard any good theories on why Earth produced so much granite and neither of the other rocky bodies we've looked at in detail seem to have much, if any?

-the other Doug

[atomoid]

...You can get carbonatite volcanic rocks, at least some of which form when magma eats a lot of limestone and you actually have black lava flows with carbonate minerals in them that turn white (on the surface) as they cool.  There's one active carbonatite volcano in Africa, I don't recall if it's carbonates come from assimilated limestone or what....

Thats probably Ol Doinyo Lengai.
dig through the many pictures linked above, this place is a geologic gem, truly amazing stuff. It is the only volcano in the world that erupts natrocarbonatite lava, which contains almost no silicon and is only about half as hot (500c) as basaltic lava so it glows dimly and looks more like mud volcano during the day.

[edstrick]

"Ghods" is an old sciencefictional fannish term, more or less nondemoninational and non-offending. Semantically, it goes with the old fannish drink, "Bheer"

[Guest_BruceMoomaw_*]

Ohkay.