[meteorite-list] Black inclusions in NWA R-Chondrites?

From: Gerald Flaherty <grf2_at_meteoritecentral.com>
Date: Fri Aug 11 09:22:53 2006
Message-ID: <001a01c6bd49$314fbf50$6402a8c0_at_Dell>

Man! that's an incredible of the individual. everything's in such outlandish
focus.
Jerry Flaherty
----- Original Message -----
From: "Jeff Kuyken" <info_at_meteorites.com.au>
To: "Meteorite List" <meteorite-list_at_meteoritecentral.com>
Sent: Friday, August 11, 2006 7:39 AM
Subject: Re: [meteorite-list] Black inclusions in NWA R-Chondrites?


> G'day,
>
> I've updated my page with more info and some better images. There are also
> some really interesting and relevant PDF abstracts that can be downloaded
> too.
>
> http://www.meteorites.com.au/features/nwa2921.html
>
> I couldn't help but notice a little similarity with a primitive clast I
> have
> in another unrelated meteorite, NWA 3119 (LL4).
>
> http://www.meteorites.com.au/features/nwa3119.html
>
> Cheers,
>
> Jeff
>
>
> P.S. Thanks to Norbert Kammel for slicing this beauty for me!
>
>
>
> ----- Original Message -----
> From: Jeff Kuyken
> To: Meteorite-list_at_meteoritecentral.com ; bernd.pauli@paulinet.de
> Sent: Tuesday, July 25, 2006 9:15 PM
> Subject: Re: [meteorite-list] Black inclusions in NWA R-Chondrites?
>
>
> Thanks to everyone who replied both on and off-list regarding the Rumuruti
> chondrites and their black inclusions. I will update my page over the
> next week or two with the info.
>
> Thanks again,
>
> Jeff
>
>
> ----- Original Message -----
> From: bernd.pauli_at_paulinet.de
> To: Meteorite-list_at_meteoritecentral.com
> Sent: Tuesday, July 25, 2006 4:25 AM
> Subject: [meteorite-list] Black inclusions in NWA R-Chondrites?
>
>
> Hi Jeff and List,
>
> "I'm hoping someone may know of an abstract/personal/web info on the black
> (xenolithic?) inclusions found in some of the NWA R-Chondrites? Any info
> would be appreciated either on or off-list." Here is an example:
>
> http://www.meteorites.com.au/features/nwa2921.html
>
> Beautiful specimen with a very conspicuous, large, dark clast and another
> equally large but light greyish-brown clast set in a medium-gray matrix
> (this light-dark structure is typical of regolith breccias).
>
> As for the black inclusion, I don't think it is xenolithic. It represents
> unequilibrated material of low(er) petrologic type. Hence all those tiny
> chondrules set in a dark matrix that resembles that of carbonaceous chon-
> drites.
>
> The light- to medium-colored matrix areas show only few chondrules and/or
> chondrule relics and thus correspond to petrologic types 5 or 6. The dark,
> chondrule-rich clasts are unequilibrated and correspond to type 3.x (about
> 3.8 some sources say).
>
> But: the dark clasts are NOT carbonaceous but are due to the dispersion of
> tiny grains of sulfides and Cr-spinels, which causes silicate darkening.
>
> My beautiful NWA 3098 (R5) and my latest addition, NWA 2943 (R3-6), which
> is still in San Diego with Cap'n Blood, also show these dark,
> unequilibrated
> clasts.
>
> But, whereas my NWA 3098 from Stefan clearly shows chondrule-poor, light
> clasts and a few small but chondrule-rich dark clasts (see JPEGs in my
> private mail to you), the NWA 2943 from Michael Blood has an overall
> higher abundance of chondrules - the chondrules are more evenly
> distributed.
> throughout the busy matrix.
>
> Best wishes,
>
> Bernd
>
> Here are some useful references:
>
> BLAND P. et al. (1992a) A unique type 4 chondrite from
> the Sahara - Acfer 217 (abs. Meteoritics 27, 1992, 204-205).
>
> BISCHOFF A. et al. (1994a) Acfer 217 - a new member of
> the Rumuruti chondrite group (Meteoritics 29, 264-274).
>
> DIXON E.T. et al. (2003) 39Ar-40Ar chronology
> of R chondrites (MAPS 38-3, 2003, pp. 341-355).
>
> JACKEL A. et al. (1996) DaG 013 - A new Saharan Rumuruti-
> chondrite (R3-6) with highly unequilibrated (Type 3) fragments
> (abs. Lun.Plan. Sci. 27, 595-596).
>
> BISCHOFF A. (2000) Mineralogical characterization of
> primitive, type-3 lithologies in Rumuruti chondrites
> (MAPS 35-4, 200, pp. 699-706).
>
> BISCHOFF A. et al. (2001) Mineralogy, Chemistry, and noble
> gases of the unpaired Rumuruti chondrites NWA 753 and NWA 755
> (MAPS 36-9, 2001, A021).
>
> LINGEMANN C.M. et al. (2000) Rumuruti chondrites: Origin and
> evolution of primitive components (MAPS 35-5, 2000, A098).
>
>
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Received on Fri 11 Aug 2006 09:22:27 AM PDT