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 have no Map nor do I know if a map exists. Definitely something I'd like to see. I'm not sure if someone out there is keeping track of all of the sulfate deposits -- I have seen maps like that - check here. But I think these things are changing on the month to month basis as CRISM and OMEGA make new discoveries.

We currently have no comprehensive theory for ice deposits on Mars or how they got there -- we simply think they were at Meridiani. Now we pose two mechanisms for what may have happened:
1) Obliquity variations: Basically the angle of tilt of Mars' axis of rotation vis a vis the Sun is thought to have varied considerably with time. Sometimes dipping down to as low as 40 degrees from vertical. These obliquity variations could cause ice to be redistributed from the polar regions to the equator. The ice would then move back again when the obliquity became more vertical. This might provide a mechanism for depositing large amounts of ice early in Mars' history on the equator, and then removing it again.

2) Polar wander -- this idea is that the actual map location of the axis of rotation of Mars was in a different place early in the history of Mars (before the growth of Tharsis). As Tharsis grew, it caused the axis of rotation to migrate across the planet until it reached its final location. Everybody is pretty sure this happened, but no one knows how large of an effect it had. It could have only moved a few degrees, while it may have moved all the way from the equator. We speculate based on the antipodal hydrogen deposits, and layered terrain in Arabia, that a paleo-pole was located near Meridiani. But if you ask most Mars scientists who are familiar with this subject you would find extreme skepticism -- for valid reasons. Mostly having to do with age relationships of the terrain in question and the growth of Tharsis.