[meteorite-list] Timing is Everything

[MARSROX 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