[meteorite-list] New Met Bulletin Approvals - new Czech meteorites

From: Carl Agee <agee_at_meteoritecentral.com>
Date: Wed, 22 Feb 2012 10:20:52 -0700
Message-ID: <CADYrzhraa3s5CC1SxexQy9Vbn5B+8f4Lfx8DJhtpfEqRRn5_2w_at_mail.gmail.com>

Hi Gary,

Yes, 20 years seems a bit short for W3. I know it rains a lot in Czech
Republic -- more than Roosevelt County!, but here are some estimates
of the terrestrial ages of the weathering grades taken from Wlotzka,
F., Meteoritics, vol. 28, no. 3, volume 28, page 460-460:


"A correlation between these weathering grades and the terrestrial
ages was shown for meteorite finds from Roosevelt County, New Mexico
[1]. In these climatic conditions the weathering grades W2 to W6
develop in the following times: W2, 5000 to 15,000 yr; W3, 15,000 to
30,000 yr; W4, 20,000 to 35,000 yr; W5 and W6, 30,000 to >45,000 yr.
Similar terrestrial ages were found for chondrites of these weathering
grades from the Lybian and Algerian Sahara [2,3]. Antarctic meteorite
finds weather much more slowly. A check of 53 Antarctic ordinary
chondrites (of hand specimen weathering categories A to C) showed only
9 of grade W2, the rest being W1. Among the W1s is ALHA77278 (category
A) with a terrestrial age of 320,000 yr"

Best regards,

Carl Agee

PS: we don't what the climate was like in Roosevelt Co. 30,000 years
ago, maybe it was wetter too!


Message: 1
Date: Tue, 21 Feb 2012 07:04:54 -1000
From: Gary Fujihara <fujmon at mac.com>
Subject: Re: [meteorite-list] New Met Bulletin Approvals - new Czech
       meteorites
To: "Jan Woreczko - www.meteoritica.eu" <ebay at biol.uw.edu.pl>
Cc: meteorite-list at meteoritecentral.com
Message-ID: <6E6A9F8F-96EF-43A4-BD5A-F4BE936CE236 at mac.com>
Content-Type: text/plain; charset=windows-1252

Aloha Jan,

>From just a cursory glance at the metbull entry for Benesov (a), I would surmise a reason for the non-fall classification is due to the fact that much time had elapsed from the witnessed fireball on May 7, 1991 and the actual recovery of material on April 9, 2011. Because almost twenty years had passed, there can be no assurance that the recovered pieces are associated with the witnessed sightings.

Additionally, Benesov (a) is an LL3.5 and Benesov (b) is an H5 and
were found on the same day 250m apart, both with a weathering grade of
W3. Characteristics are "Weathered fragments lacking fusion crust.
The meteorites resemble the terrestrial stones and slag found in the
field." To me, this implies that the recovered pieces have a
terrestrial age greater than 20 years.

gary

On Feb 21, 2012, at 6:18 AM, Jan Woreczko - www.meteoritica.eu wrote:

> Ha
> Why are these findings are not classified as a falls?
>
> Bene?ov (a) http://www.lpi.usra.edu/meteor/metbull.php?code=54854
> Bene?ov (b) http://www.lpi.usra.edu/meteor/metbull.php?code=54855
>
> http://translate.google.pl/translate?sl=pl&tl=en&js=n&prev=_t&hl=pl&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwiki.meteoritica.pl%2Findex.php5%2FBene%25C5%25A1ov
>
>
> Best wishes,
> Woreczko
>
> ______________________________________________
>
> Visit the Archives at http://www.meteoritecentral.com/mailing-list-archives.html
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list

Gary Fujihara
Big Kahuna Meteorites (IMCA#1693)
105 Puhili Place, Hilo, Hawai'i 96720
http://bigkahuna-meteorites.com/
http://shop.ebay.com/fujmon/m.html
(808) 640-9161

-- 
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: agee at unm.edu
http://meteorite.unm.edu/people/carl_agee/

Received on Wed 22 Feb 2012 12:20:52 PM PST