Can't resist doing some arm-chair science... usually a bad move, but oh
well... I'll probably end up retracting much of this speculation...
There IS something strange about this meteorite to me. I don't know how
good the XRF analysis is, but it is not what I would expect from an L
chondrite. These analyses show a 30-40% enrichment in Ca and Al
relative to Si over what an L chondrite should be, and siderophiles are
~20% too high as well. If these are accurate, then there has been
fractionation, suggestive of enrichment in low-melting components (which
is odd). Sodium does not fit this story, but it's a harder element to
analyze by xrf. I also agree that coarse poikilitic grains are hard to
explain by solid-state metamorpism, but they could also be derived from
relict chondrules. If this rock was melted to a large extent, I'd
expect it to be depleted in metal and sulfide. So I'm betting that the
whole system has experienced low-degree partial melting, and some of
these melts have infiltrated this particular chunk of
high-metamorphic-grade L chondrite.
I agree with Carl that this has hallmarks of what many people call a
type 7 chondrite. But the whole issue of how to draw lines (or if there
ARE lines) between primitive achondrites, type 7 chondrites, and
products of shock heating/melting is very fuzzy and tends to be highly
interpretive. In a sense, this is the same discussion that surrounds
Portales Valley, an ordinary chondrite that has also "been around the
block."
Here is an article on Katol that Laurence Garvie pointed me to:
http://www.geosocindia.org/abstracts/2013/feb/p151-157.pdf
Jeff
On 12/31/2013 6:33 PM, Jason Utas wrote:
Hello Carl, All,
The low standard deviation on Fa and Fs denotes a high degree of
equilibration, not just "5 or 6." "Five or above" would be more
accurate. The nearly absent chondrules and high Wo are at [or beyond]
type 6. If you're a researcher who believes in type 7 chondrites,
since not all do.
Based upon similar observations, one would simply call Al Haggounia
001 an aubrite, or an EL3 if one were lucky enough to find an
unequilibrated chondrule. The textural observations would be
irrelevant. If we looked at other meteorites in a similar fashion,
subgroups and textural designations would disappear.
Since nomenclature blows back and forth, this is something of a
semantic argument; as I understand it, the "poikilitic shergottite"
you recently analyzed would have been a "lherzolite" only a few years
ago, and no amount of discussion then or now would have changed that.
And there is of course variation in analyses. NWA 5205 is paired with
NWA 5421 and our NWA 6501. Which was supposedly paired with NWA 6283.
Very distinctive material, with classifications ranging from LL3.2 to
LL3.7 to H3.6.
But you did note that the shergottite was poikilitic. So is Katol.
This stone has been metamorphosed in a unique way for a chondrite, and
its classification required a much greater degree of attention because
of that. But the result does not reflect that. Just like Al
Haggounia 001, the "aubrite." It's odd, and I do think that
'pigeonholing' is the right term to use here.
Regards,
Jason
www.fallsandfinds.com
On Tue, Dec 31, 2013 at 2:45 PM, Carl Agee <a...@unm.edu> wrote:
Mike, Andy, Jim,
I don't have bias one way or another in the case of Katol, but looking
at the data in the write-up this is a clear-cut L6 chondrite -- no
ambiguity. There are chondrules albeit highly equilbrated, the
olivines are L6, the pyroxenes are L6, the oxygen isotopes are
L-chondrite. If there were no chondrules, high Wo and OC-type olivine
and pyroxene, then one could make the case for type 7. I'm just going
by the numbers given in the write-up, I haven't looked at this beyond
a quick glance in hand specimen, not an achondrite -- period.
Carl
*************************************
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126
Tel: (505) 750-7172
Fax: (505) 277-3577
Email: a...@unm.edu
http://meteorite.unm.edu/people/carl_agee/
On Tue, Dec 31, 2013 at 3:19 PM, Michael Farmer <m...@meteoriteguy.com> wrote:
I was also under the impression that this was transitional likely between L
chondrites and primitive achondrites.
Michael Farmer
Sent from my iPhone
On Dec 31, 2013, at 3:15 PM, Andy Tomkins <rockdo...@gmail.com> wrote:
With great respect and just to be a little bit controversial... With a high
wollastonite content in the opx like that, sparse remnant chondrules and
many of the other features, perhaps this might be a L7? An example of why
there needs to be a clearer definition of what defines Type 6 from Type 7?
Andy Tomkins
On Wednesday, 1 January 2014, Andy Tomkins wrote:
On Wednesday, 1 January 2014, Carl Agee wrote:
Hi Mike,
No doubt an interesting meteorite! I guess I should qualify it by
saying the oxygen and the olivine and pyroxene geochem data are garden
variety EOC. I guess looks can be deceiving -- yet another testimony
to lab data being the "blind taste test".
Carl
*************************************
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126
Tel: (505) 750-7172
Fax: (505) 277-3577
Email: a...@unm.edu
http://meteorite.unm.edu/people/carl_agee/
On Tue, Dec 31, 2013 at 10:23 AM, Michael Farmer <m...@meteoriteguy.com>
wrote:
Carl, the huge metal nodules, the large green crystals throughout the
matrix, very odd meteorites, everyone who looked at it thought it was an
achondrite, including many scientists.....
I've never seen an L6 with white matrix and some pieces nearly green
with crystals.
Not your garden variety L6 for sure.
Michael Farmer
Sent from my iPad
On Dec 31, 2013, at 10:14 AM, Carl Agee <a...@unm.edu> wrote:
Super write-up by Laurence Garvie, but strange that there was so much
mystery surrounding what turns out to be garden variety "L6", albeit a
nice fresh fall. I wonder why people thought it was "achondrite-ung"?
Oxygen and geochem are unequivocal EOC, no mystery at all.
Carl Agee
*************************************
Carl B. Agee
Director and Curator, Institute of Meteoritics
Professor, Earth and Planetary Sciences
MSC03 2050
University of New Mexico
Albuquerque NM 87131-1126
Tel: (505) 750-7172
Fax: (505) 277-3577
Email: a...@unm.edu
http://meteorite.unm.edu/people/carl_agee/
On Tue, Dec 31, 2013 at 9:06 AM, Jim Wooddell
<jim.woodd...@suddenlink.net> wrote:
Nice GeoChem data. Interesting to see the XFR data included.
Happy New Year!
Jim Wooddell
On 12/31/2013 8:14 AM, karmaka wrote:
Dear list members,
Katol is officially listed as an L6 in the Bulletin now!
http://www.lpi.usra.edu/meteor/metbull.php?sea=Katol&sfor=names&ants=&falls=&valids=&stype=contains&lrec=50&map=ge&browse=&country=All&srt=name&categ=All&mblist=All&rect=&phot=&snew=0&pnt=Normal%20table&code=58500
Happy new year 2014 to all of you!
Martin
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