[meteorite-list] Timing is Everything

From: MARSROX_at_aol.com <MARSROX_at_meteoritecentral.com>
Date: Wed Apr 20 16:53:17 2005
Message-ID: <54.42a09621.2f981b27_at_aol.com>

Thanks to Mike Jensen for the heads-up on the paper newly published by Dr.
Jeff Grossman and Adrian Brearley refining the measurement of classification
for chondrites.

In the last couple of days, including today, I've been working on a feature
for "Meteorite" magazine that includes discussions I had with Dr. Brigitte
Zanda, the curator of the NHM met collection in Paris about her research in
chondrule formation. We talked about her discovery of chondrules in a plastic
state during formation in Semarkona LL3.0, perhaps the most primitive
chondrite.

The most obvious point here is that chondrules were observed in formation
that are not spheres. It's an exciting discovery in today's most happenin'
meteorite research area - the origins of chondrules. You can read more of this
discussion in "Meteorite" come August.

One side area of interest with all this, is that petrology is now determined
by using "thermaluminesence." This technique is a bit more sophisticated
than when one looks at a slice of something and expertly guesses, "Oh, that
looks like a L5."

A discussion has risen about thermaluminesence measuring because it's
possible that terrestrial weathering can alter the outcome of a pre-terrestrial
event, changing what observers think is a most primitive 3.0 to a 3.2 or 3.4.

On my first quick read of this (I have a meeting in 30 minutes), Jeff and
Adrian's paper seems to propose extremely accurate measuring of petrology in
type 1 chondrules by combining electron microscopy and cathodoluminescence in
their observations. The resultant measurements would be several times more
accurate than present thermaluminesence techniques, i.e. resulting in
petrology's of 3.05, 3.10, etc., instead of just 3.0 or 3.2.

However, I'm assuming that cathodoluminescence (can't type that too many
times without misspelling) is different from thermaluminesence (and I'm sure
someone will soon let me know if it isn't - smiley face here). But this is great
work and seems to me to be exciting news.

Kevin Kichinka
Received on Wed 20 Apr 2005 04:52:55 PM PDT