Meridiani Ice theory, New theory for the formation of the Meridiani bedrock Options

[Doc]

Hi all, long time no see.
Yet another theory to explain the origin for the bedrock encountered by Opportunity.
I first heard of this new theory from Universe Today;

http://www.universetoday.com/2009/02/16/ne...t-mars-equator/

An abstract is available at http://www.nature.com/ngeo/journal/vaop/nc...bs/ngeo438.html

The theory is interesting, but I would really be interested to know how it explains the spherules seen by Opportunity not to mention the vugs.
Thoughts any one?

[Paul Niles]

I'm glad to see a few people here that are interested in this. The idea is that we have two stages of aqueous alteration here.

The first stage caused the formation of sulfates and weathering of primary basaltic material into silica and phyllosilicates. We propose that the silicates weathered in very small pockets within the ice where liquid water films+silicates+acidic aerosols can all react together. The reason we call on this idea is because the chemistry of the Meridiani outcrops shows that all of the major cations are still present in the abundances you would expect from a fresh basalt, but are present in strongly altered mineral phases (sulfates, silica, phyllosilicates). So it is as if the whole outcrop was weathered in a closed system.

The second stage occurs during diagenesis of these materials after deposition. This is very similar to the ideas already proposed by Squyres et al.. Here we propose that the grains, made up of highly hydrated phases from the sublimation residue of this massive ice deposit, are reworked by aeolian processes and deposited in a crossbedded sequence. As they are buried they dehydrate -- and generate enough water to power a very limited diagenesis to form the blueberries. It has to be very limited because of the presence of both hematite and jarosite which indicates that whatever reaction happened, it didn't go to completion.

Paul