Space/Science — HabitableZone

Space/Science » in reply to Not in a million years!

Sulfate rich magmas have no Earth analog, I believe
Philip Simon — (archived)

http://www.otago.ac.nz/geology/staff/jdlw/Fieldguide_sml.pdf

Some of the photos in the above link look a bit like some Columbia rocks. It is an interesting paper.

As far as the crystal size, it is a common misconception that extruded rocks have to be fine grained. Magmas can be emplaced as lacoliths and have slow cooling producing large crystal sizes of one or more phases while only the matrix is fine grained.

The bedded deposits seen so far at Columbia seem highly irregular, and blob or pillow like on the large scale, and nodular on a small scale. The highly altered zones are also irregular, but are they so irregular that they resemble paleosoils on top of subareal basalt flows? Adnittedly the exposures seen so far are not so good as to be definative. I believe the subaqueous eruption scenario (which could also include the turbidites of the above cited paper) could explain some of the oddity of the less altered, but still quite altered rock in the C. hills. These are far from being just a simple vesicular basalt like most of the rocks in the crater plain.

I'll try to keep an open mind. The one Nasa explanation I saw so far was that these may be reworked (redeposited) basalts. The bedding is too highly irregular, for the most part, to be that, I believe. A subaqueous eruption of a sulfate and water rich magma in to a water that is also sulfate and sulfuric acid rich could possibly occur without all the explosions and clasts of Terrestrial analogs. Mid ocean ridge eruptions of pillow basalts are surprisingly tranquil.

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