[meteorite-list] Chondrule formation

[Alan Rubin]

The question was raised if chondrules occur in achondrites or moon rocks. 
If you look back at papers from 1970 - 1972, there are reports of "lunar 
chondrules" found in the first returned Apollo samples.  These "chondrules," 
as nearly everyone acknowledges, are millimeter-size impact-melt spherules 
produced after collisions of meteorites with the lunar surface.  Some folks 
think that chondrules in chondrites also formed this way, but most chondrule 
researchers believe that chondrules were formed as isolated droplets in the 
solar nebula.  If this is correct, then after being melted, they would have 
cooled quickly because there was little or no insulating material around 
them.  Only later would these chondrules accrete along with CAIs, matrix, 
metal and sulfide assemblages, etc. to form planetesimals which later 
accreted into larger bodies.  If chondrules indeed formed as isolated 
droplets in the nebula, then if the planetesimals into which they 
subsequently accreted ever melted, then the chondrules would also melt and 
the textural evidence for them would be forever erased.
Alan Rubin


----- Original Message ----- 
From: "Greg Stanley" <stanleygregr at hotmail.com>
To: <epgrondine at yahoo.com>; <meteorite-list at meteoritecentral.com>
Sent: Friday, October 02, 2009 1:51 PM
Subject: Re: [meteorite-list] Chondrule formation



Hello All:

I had a thought:

It seems to me that chondrules are prevalent in meteorites blasted from 
asteroidal bodies and not from planetary bodies. For example, do chondrules 
exist (or have been found) on any meteorites from the moon, mars or maybe 
from Mercury (Angrites?)? Now I understand that these are called 
achondrites, and thus they do not have chondrules, but it seems that 
chondrites are only from asteroidal bodies (or perhaps comets). With that 
said, maybe there is a relationship between formation of rock without 
gravity (or a very small amount of gravity); chondrules form initially 
during the formation of the solar system, and then later over millions of 
years are altered on planetary bodies under a gravitational force.

Just my two cents worth.

Greg S.

----------------------------------------
> Date: Fri, 2 Oct 2009 11:58:02 -0700
> From: epgrondine at yahoo.com
> To: meteorite-list at meteoritecentral.com
> Subject: Re: [meteorite-list] Chondrule formation
>
> Hi all -
>
> "We don't know crap..." Hey!, who stole my line?
>
> But that's okay, I can come up with another one:
> We don't know crap about the impact hazard,
> and NASA senior managers know less than that.
>
> E.P. Grondine
> Man and Impact in the Americas
>
>
>
>
> ______________________________________________
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