[meteorite-list] Oriented chondrules?

From: mark ford <markf_at_meteoritecentral.com>
Date: Mon Mar 21 13:24:54 2005
Message-ID: <6CE3EEEFE92F4B4085B0E086B2941B31244D8F_at_s-southern01.s-southern.com>

True, I suppose it could be some sort of 'flow effect', as the finer
matrix material interspersed with the Chondrules, presumably when the
whole rock coagulated it would have been very loose (and hot) at first
before being compacted under the mass of rock. Perhaps Oriented
Chondrules originate as part of much larger bodies than the
non-orientated ones .....

I wonder if some sand and a few small round pebbles could be used to
simulate the effect in some way?...

You often get oriented pebbles in terresrial Eocene cliff deposits,
where the stones are all aligned, maybe a similar process is going on
(the stones behaving like large chondrules)

Best,
Mark Ford


-----Original Message-----
From: Darren Garrison [mailto:cynapse_at_charter.net]
Sent: Tuesday, March 08, 2005 11:41 AM
To: Meteorite-list_at_meteoritecentral.com
Subject: Re: [meteorite-list] Oriented chondrules?

On Tue, 8 Mar 2005 01:31:02 -0700, "Graham Christensen"
<voltage_at_telus.net> wrote:

>Hi Darren
>Chondritic meteorites come from asteroids that aren't quite large
enough to
>have completely melted, but usually still large enough to cause some
thermal
>alteration. The heat that was present might have made the chondrules
>sufficiently pliable that they squished into oval shapes due to the
downward
>pressure from the material that was above it in its parent asteroid.
Or,
>possibly the chondrules were already elongated but the pressure from
above
>caused them to settle that way while the matrix was still soft.
>
>Just throwing out ideas,
>Graham

Possible, I suppose. But look at the one elongated chondrule near the
top center that is oriented
close to 90 degrees differently than the majority of them. That kind of
(to me, at least) increases
the appearance of some sort of flowing of the material. You know how in
a stream of material
(water, air) an object will try to line up to cause the least resistance
(which would be the
majority of the chondrules with the axis pointed in one direction) or,
if the angle to the flow is
just right, would have the flattest side "pushing" agaist the flow and
would end up aligned
perpendicular to the flow. (Much like how a "heat shield" oriented
meteorite forms). "Squishing"
would seem to have a harder time explaining (in my non-expert opinion)
how that one chondrite is
flattened and aligned in a nearly perpendicular direction.
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Received on Tue 08 Mar 2005 07:13:47 AM PST