Meridiani soil close-ups

Some of the raw microscopic imager photos from Opportunity of the soil
at the Meridiani Planum site are at:

http://marsrovers.jpl.nasa.gov/galle...nity_m010.html

http://marsrovers.jpl.nasa.gov/galle...nity_m009.html

Take a look at those spheres and tubes! If this is where the hematite
is, there is going to be a buttload of discussion on their genesis. Some
these things look like spring or travertine features, although I've also
seen pisolites and speleothem-like features that look like these objects
in very mature soil carbonate horizons that have been brecciated and
reactivated. By the way, many soil and spring features that look like
this on earth involve algae or bacteria. Maybe we are looking at pieces
of a broken up and redistributed iron pan horizon in a soil? Maybe a
shallow soil horizon that has been wind-eroded?
--
Tim Demko
http://www.d.umn.edu/~tdemko

Timothy Demko wrote:

Some of the raw microscopic imager photos from Opportunity of
the soil at the Meridiani Planum site are at:


http://marsrovers.jpl.nasa.gov/galle...nity_m010.html


http://marsrovers.jpl.nasa.gov/galle...nity_m009.html

Take a look at those spheres and tubes! If this is where the
hematite is, there is going to be a buttload of discussion on
their genesis. Some these things look like spring or
travertine features, although I've also seen pisolites and
speleothem-like features that look like these objects in very
mature soil carbonate horizons that have been brecciated and
reactivated. By the way, many soil and spring features that
look like this on earth involve algae or bacteria. Maybe we
are looking at pieces of a broken up and redistributed iron
pan horizon in a soil? Maybe a shallow soil horizon that has
been wind-eroded?

I was having a look at the Pathfinder section of the JPL website
yesterday, to see what science conclusions they had come to. As
far as I can tell, scientists are virtually certain that the
jumble of rocks and sediment seen in Pathfinder's images were
deposited there by a catastrophic flood event somewhere between 1
and 3 billion years ago, but that since then, very little change
has occurred. If the same applies to the Meridiani site (that
it's extremely old), is it possible that the fine 'soil' at that
location is accumulated fallout from meteorite impacts? I'm
wondering if the presence of at least some atmosphere on Mars
would mean that larger bodies of rock ejected from such impacts
would land first, with smaller particles being more affected by
air resistance and come down a bit later, so ending up with just
the finest material on top. It seems odd to me that the material
in this crater (and on the horizon?) has such a smooth surface,
unlike the Viking, Pathfinder and Spirit sites. Given that the
atmosphere is very thin, would the wind be able to blow particles
around enough to fill the crater with this smooth layer of
material? Or is it possible that this material was deposited
under water, since the crater was formed? Sorry for all the
questions :-)