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Re: Clays in Meridiani.

Subject: Re: Clays in Meridiani.
From: "don findlay"
Date: 7 Sep 2006 19:18:30 -0700
Newsgroups: sci.astro, alt.sci.planetary, sci.geo.geology, sci.physics
jonathan wrote:
> "Robert Clark" <[email protected]> wrote in message
> news:[email protected]
> Just saw this on
> Mineralogy of the light-toned outcrop at Meridiani Planum as seen by
> the Miniature Thermal Emission Spectrometer and implications for its
> formation.
> doi:10.1029/2005JE002672, 2006
> "Abstract
> Analysis of Miniature Thermal Emission Spectrometer (Mini-TES) data has
> led to the recovery of a pure end-member spectral shape related to the
> light-toned outcrop observed at Meridiani Planum. Data from the MER
> Mössbauer spectrometer, APXS, and previous Mini-TES measurements were
> used to constrain a spectral library used to determine the mineralogy
> of the outcrop from this spectral shape. Linear deconvolution of the
> outcrop spectral shape suggests that it is composed primarily of
> Al-rich opaline silica, Mg-, Ca-, and Fe-bearing sulfates, plagioclase
> feldspar, nontronite, and hematite. Conversion of modeled mineralogy to
> chemistry shows good agreement with the chemical composition of the
> outcrops determined by APXS. Details of the analysis procedure and
> implications for the formation of the outcrop are discussed along with
> terrestrial analogs of the ancient environment at Meridiani."
>  According to the authors the spectra of the Meridiani bedrock is best
> matched by a composition that includes 10% nontronite clay.
>     Bob Clark
> So that would mean a less acidic environment that is more friendly
> to life I believe.  All those layered rocks and outcrops were formed
> by evaporation of shallow seas and weathered by water.
> Doesn't this paint a picture of Mars that has substantial underground
> water that flows to or near the surface periodically?  Alternating wet
> and dry periods. Perhaps as ice ages wax and wane?
> The article also claims that water is about 5% by weight of the outcrops.
> It's starting to look like water, not volcanism, is the more active
> weathering process.
> The idea that Mars has been dry for geologic time just doesn't
> sound anything at all like the truth. Does anyone know how
> long Mars ice ages last?  I'd suspect they'd be rather
> chaotic with the complicated orbit.

Volcanism is a constructive process, building up layers upon layers
upon layers upon layers upon layers upon layers upon layers upon layers
upon layers upon layers upon layers upon layers upon layers upon layers
upon layers upon layers upon layers.

Then it gets rubbed away and redistributed.

 Why don't you ask them a 'sensible' question, .. like, they can
get a grip of, "Is there Plate Tectonics on Mars"  ...and .."If
lava keeps getting extruded on the one side of the planet, why isn't
there a great big  en hole in it round the other side...?"

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