[meteorite-list] Fw: Still un answered question

From: Sterling K. Webb <sterling_k_webb_at_meteoritecentral.com>
Date: Thu, 10 Jan 2008 14:46:16 -0600
Message-ID: <009f01c853c9$d8956360$795fe146_at_ATARIENGINE>

Hi, Jerry, List,

    The meteorites of Roosevelt Co. are found in wind-ablated
pits, called "blow-outs," which fill with sand and preserve them.
http://epswww.unm.edu/meteoritemuseum/nmmeteorites.htm

    The age of the surfaces that are being searched? 50,000
to 90,000 years old!

http://adsabs.harvard.edu/abs/1992Metic..27..460Z
The abstract:
    "We have obtained minimum age estimates for the sand units
underlying the two largest meteorite deflation surfaces in Roosevelt
County, New Mexico, USA, using thermoluminescence dating
techniques. The dates obtained ranged from 53.5 (+/- 5.4) to
95.2 (+/- 9.5) ka, and must be considered lower limits for the
terrestrial ages of the meteorites found within these specific
deflation surfaces. These ages greatly exceed previous
measurements from adjacent meteorite-producing deflation
basins. We find that Roosevelt County meteorites are probably
terrestrial contemporaries of the meteorites found at most
accumulation zones in Antarctica. The apparent high meteorite
accumulation rate reported for Roosevelt County by
Zolensky et al. (1990) is incorrect, as it used an age of
16 ka for all Roosevelt County recovery surfaces.
We conclude that the extreme variability of terrestrial
ages of the Roosevelt County deflation surfaces effectively
precludes their use for calculations of the meteorite accumulation
rate at the Earth's surface."

The full PDF:
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1992Metic..27..460Z&amp;data_type=PDF_HIGH&amp;whole_paper=YES&amp;type=PRINTER&amp;filetype=.pdf

Another area similar to Roosevelt Co. is described
and the mechanism of preservation is given in more detail:
https://e-reports-ext.llnl.gov/pdf/237492.pdf
    "Most meteorites from this area have been found on the
floors of active deflation basins (blowouts) that have
been excavated from a mantle of sand dunes. This area
has no apparent fluival or permafrost activity within
the last 50,000 years [e.g., 4,5], suggesting that only
prevailing winds and natural aridity aid in the concentration
and preservation of meteorites."

Has anyone searched this area (Lea Co., NM) further?
(Did it "pan out"?)


Sterling K. Webb
---------------------------------------------------------------------
----- Original Message -----
From: "Jerry" <grf2 at verizon.net>
To: "meteoritelist meteoritelist" <meteorite-list at meteoritecentral.com>
Sent: Thursday, January 10, 2008 2:10 PM
Subject: [meteorite-list] Fw: Still un answered question



Jerry Flaherty
----- Original Message -----
From: "Matson, Robert D." <ROBERT.D.MATSON at saic.com>
To: "Jerry" <grf2 at verizon.net>; "Peter A Shugar" <pshugar at clearwire.net>;
"LIST" <meteorite-list at meteoritecentral.com>
Sent: Thursday, January 10, 2008 1:39 PM
Subject: RE: [meteorite-list] Still un answered question


Nope. Just *ONE* meteorite hunter -- Skip Wilson -- a very methodical
and thorough one. "A meteorite every 22.5 square miles" doesn't really
tell the story -- Skip searched (continues to search?) a much smaller
area than this, but he is very selective about the surfaces searched.
In ideal locations, the meteorite density is much, much higher than
1 per 22.5 square miles. If the average terrestrial lifetime of a
meteorite is, say, 5000 years, the expected density is more like 3
meteorites per square mile. --Rob

P.S. Feel free to forward this to the meteorite list. You'll see
that I included it in the "To" list, but I guarantee it won't show
up there.

-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Jerry
Sent: Thursday, January 10, 2008 9:25 AM
To: Peter A Shugar; LIST
Subject: Re: [meteorite-list] Still un answered question

Sounds like ideal search conditions and a hulava lot of meteorite
hunters.
Jerry Flaherty
----- Original Message -----
From: "Peter A Shugar" <pshugar at clearwire.net>
To: "LIST" <meteorite-list at meteoritecentral.com>
Sent: Thursday, January 10, 2008 12:04 PM
Subject: [meteorite-list] Still un answered question


> Still unanswered is the other question:
> And then there is little dinky Roosevelt Co, NM at just 2,455 sq miles
and
> it has a staggering 109 meteorites, which comes to one for every 22.5
sq
> miles. What gives?
> They are of a wide variety of classifications, so it can't be turning
> every piece in
> for classification. I can't speak for anyone else, but I find this
very
> puzzling.
> Any thoughts, List?
> Pete
> ______________________________________________
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Received on Thu 10 Jan 2008 03:46:16 PM PST


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