[meteorite-list] H2 or L2 CLASS METEORITES

From: MexicoDoug <MexicoDoug_at_meteoritecentral.com>
Date: Thu, 29 Mar 2007 20:02:33 -0600
Message-ID: <01a801c7726f$ae1693c0$9ac85ec8_at_0019110394>

Mike (2), Looks like I just learned a lot tonight - in fact type "1"
actually is more severely altered by water! So scratch my PS, and thanks
for the comment. If you read the text, though, you will see that type "3"
(as far as I can see doesn't mean no alteration (as he explicitly stats with
aqueous), so I think that still leave the door open.

Wow, now it finally makes sense when comparing my CM2 to my CV3 - those
CM2's always didn't make sense to me...

Best, Doug



----- Original Message -----
From: "MexicoDoug" <MexicoDoug at aim.com>
To: "tett" <tett at rogers.com>; "Meteorite Mailing List"
<meteorite-list at meteoritecentral.com>
Sent: Thursday, March 29, 2007 7:43 PM
Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES


> Hi Mike,
>
> In light of Jeff's post I'd tend to yield if I were in an argument and
just
> agree. But if the purpose is to get a feel for what is happening and why,
> it's more fun to keep these ideas alive.
>
> Scientists can make conventions, and it is very hard to keep conventions
> written in stone. Until a new stone causing them to go back to the
drawing
> board. The purpose of my post was to complement your ideas and get an
> understanding of the processes. If the scientists want to define 3.0 as
the
> lowest and take into consideration a well thought out scheme, that's fine.
> Then, someone, somewhere, will come up with something that doesn't fit
some
> class and it will be worth $1000/gram and have everyone buzzing.
>
> Yielding with a good fight, and remembering the 4 billion year old rocks
> found in Australia,
> Doug
>
> PS as to McSween's chart, I think that is a red herring. After all, if
you
> were to interpret it literally as you do, type "I" carbonaceous would be
> more altered by water than type "2"!!
>
> ----- Original Message -----
> From: "tett" <tett at rogers.com>
> To: "MexicoDoug" <MexicoDoug at aim.com>; "Meteorite Mailing List"
> <meteorite-list at meteoritecentral.com>
> Sent: Thursday, March 29, 2007 7:31 PM
> Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES
>
>
> > Doug,
> >
> > Does petrologic grade 3, in essence, mean little to no thermal
alteration?
> > If so, then there can not be a type 2 even with a nice heat sink to
> protect
> > these primordial chondrules. In fact, McSween's chart on pg 63 2nd ed.
> > shows type 3 as neither aqueous altered or thermally altered. However,
he
> > does mention that these classifications are simplifications and intended
> to
> > represent a range of alteration. Why we now have LL3.7's etc.
> >
> > Although I have not found this plainly stated, I believe the intent of
the
> > classification system was that H3.0 or L3.0 or LL3.0 are thermally
> unaltered
> > and hence have pristine baby fresh chondrules.
> >
> > The parent bodies for the carbonaceous chondrites did not experience the
> > same temperatures leading to thermal alteration of their chondrules. At
> > least, I guess this is so.
> >
> > Cheers,
> >
> > Mike Tettenborn
> >
> >
> > ----- Original Message -----
> > From: "MexicoDoug" <MexicoDoug at aim.com>
> > To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
> > Sent: Thursday, March 29, 2007 9:05 PM
> > Subject: Re: [meteorite-list] H2 or L2 CLASS METEORITES
> >
> >
> > > "I was thinking about this today and I have not had time to research
> it."
> > >
> > > Hello Steve,
> > >
> > > I hope you can do some research sometime, Steve. As "H" and "L" are
> > > thought
> > > to be two unique and real parent bodies, your question can be stated
> > > alternately:
> > >
> > > "Were there any places on the H parent body or the L parent body that
> did
> > > not experience the thermally-induced alteration characteristic of
> > > unequilibrated chondrites "3", and if so, did any residue from them
> reach
> > > earth and drop meteorites?"
> > >
> > > I think the answer is "no". Harry McSween explains that on these
parent
> > > bodies, especially with reference to the onion-skin model of
asteroids,
> > > the
> > > incubation caused by radioactive disintegration warmed the whole of
the
> > > parent body uniformly enough to cook all of our H- and L-chondrites
> enough
> > > according to 'current' understanding. But that doesn't mean chance
> could
> > > have thermally isolated or provided a shady heat sink somewhere on the
> > > surface where the legendary H2 or L2 could have been protected from
its
> > > mother planetoid.
> > >
> > > Carbonaceous chondrites meteorites show "2" and essentially "1" not
> > > because
> > > they were heated, but rather because of their setting of primordial
> > > material, like celestial cementing that formed them, altered them to
> > > varying
> > > degrees with water, but not the heat on the H- and L- assumed to be
> larger
> > > parent bodies.
> > >
> > > Note since there are just two parent bodies here, it is easy to write
> off
> > > the possibility of H2 and L2 just by saying, these bodies were simply
> too
> > > warm for this to occur. If you calculate an asteroid diameter to
> explain
> > > the H3-6 distributions we know, for example, you can say how big the
> > > parent
> > > body was, and once you say how big it was, you can argue by its
thermal
> > > properties how it all got warm and sufficiently metamorphic.
> > >
> > > But this is all still conjecture. The University of Chicago is always
> in
> > > need of a few good men!! Go Steve!!
> > >
> > > Best Wishes and Best Health,
> > > Doug
> > >
> > > ----- Original Message -----
> > > From: "steve arnold" <stevenarnold60120 at yahoo.com>
> > > To: <meteorite-list at meteoritecentral.com>
> > > Sent: Thursday, March 29, 2007 5:57 PM
> > > Subject: [meteorite-list] H2 or L2 CLASS METEORITES
> > >
> > >
> > >> Hi list.I was thinking about this today and I have not
> > >> had time to research it.Are there any H2 or L2 class
> > >> meteorites that have been classified?This is a real
> > >> must thread for me.Any help would be welcome.
> > >>
> > >>
> > >>
> > >>
> > >> steve arnold,chicago
> > >>
> > >> Steve R.Arnold,chicago,Ill,Usa!!
> > >> Collecting Meteorites since 06/19/1999!!
> > >> www.chicagometeorites.net
> > >> Ebay I.D. Illinoismeteorites
> > >>
> > >>
> > >>
> > >>
> > >>
> > >
>
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Received on Thu 29 Mar 2007 10:02:33 PM PDT