I just received two small chips this afternoon but haven't had a
chance to look at them yet. But I have seen the images that Sasha
Krot, Mike Zolensky and Carl Agee made. The rock is clearly a
breccia. Sasha's chip has a CM2.0 clast surrounded by slightly less
altered material, probably CM2.2. This is consistent with the
presence of PCP which I believe I saw in some of Carl's images. The
presence of CaS (oldhamite) and reduced phosphides reported by Mike
Zolensky suggests that a projectile of an enstatite chondrite or
aubrite impacted the host and then disrupted. There may have been
subsequent mild metamorphism but little or no aqueous alteration of
the host (or at least Mike Zolensky's piece) at that point; otherwise
the oldhamite would have been destroyed. The rock has unique
features, but other meteorite breccias contain clasts of diverse
groups. Such rocks include Kaidun, Galim, Bencubbin, Almahata Sitta,
even Murchison.
Alan
Quoting Carl Agee <[email protected]>:
Hi Richard,
I haven't seen a thin section of Sutter's Mill yet, but my guess is
that it will be very dark, just like the meteorite, so maybe not that
illuminating. I prefer backscatter electron images because they not
only show texture, but also image chemical compositional variations.
Like the dark olivines in my images?- they are Mg2SiO4-rich, the
light shaded olivines are Fe2SiO4-rich. Bright patches indicate high
iron or Ti or Cr, and so on.
As to the CaO, the electron microprobe does not do carbon very well so
it usually comes up with low totals on carbonates. I looked at the
data today and we found 4 separate crystals with this composition in
one of the small SM sections -- after perusing the CM literature
today, I am pretty sure this is calcite or aragonite -- thought by
some to form during aqueous alteration and commonly found in CMs.
With respect to the classification and type, I will leave that to the
unequilibrated chondrite experts like Jeff Grossman and Alan Rubin.
MetSoc will be very interesting this year: Tissint, Sutter's Mill, and
NWA 7034. You haven't heard about NWA 7034? Oh you will...
Carl Agee
On Fri, May 25, 2012 at 7:04 PM, Richard Montgomery
<[email protected]> wrote:
Carl and List,
I'm struck by the chondrule variation...can't wait to see a TS (hi
Anne!)....so it's time to ask about the rabbit hole:
As I mentioned I'm just guessing here....not a CM2, due to chondrules
actually so present, right? Not a CM3 either (if there ever is such a thing)
due to the rim alterations and aqueous stuff; dark matrix like a CM, yet
more crowded chondrules; complete CaO crystals; lacking so far of seeing any
CAIs....what's your guess at this point??
Next Halloween I can dress up as a petrologist scientist....but won't fool
anyone. Fun to speculate, though.
Richard M
----- Original Message ----- From: "Carl Agee" <[email protected]>
To: "meteoritelist meteoritelist" <[email protected]>;
"Jeff Grossman" <[email protected]>
Sent: Friday, May 25, 2012 2:03 PM
Subject: Re: [meteorite-list] Sutter's Mill BSE - two more
Jeff,
You mean the area in the SW quadrant? It's permeated with the bright
material? It could be sulfide, but I didn't get a chance to EDS or
probe it yesterday. It's all somewhat bewildering, there is so much
look at, so I am starting with the simple stuff that give good
microprobe totals -- haha!. Beware of this meteorite! Like going down
the rabbit hole....
Carl
-----------------------------------------
Carl,
What's the difference between the two lithologies visible in the first
of these two photos?
Jeff
On 5/25/2012 2:19 PM, Carl Agee wrote:
http://www.facebook.com/photo.php?fbid=4042491099560&set=a.1076549432872.2012978.1200325441&type=1&ref=nf
http://www.facebook.com/photo.php?fbid=4042494859654&set=a.1076549432872.2012978.1200325441&type=1&ref=nf
--
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: [email protected]
http://meteorite.unm.edu/people/carl_agee/
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--
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: [email protected]
http://meteorite.unm.edu/people/carl_agee/
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