[meteorite-list] NWA 4801 - New 'Time Marker' Standard

From: Greg Hupe <gmhupe_at_meteoritecentral.com>
Date: Wed, 3 Nov 2010 17:35:59 -0400
Message-ID: <C6AD1D2FA98B4A5BB7FD10E61B838D72_at_greg323a964987>

Good Afternoon All,

In the recent past there has been discussion of whether meteorites from the
hot deserts of Northwest Africa are superior or inferior to those from
Antarctica or anywhere else, including witnessed falls. NWA 4801 is a very
fresh angrite from Northwest Africa that has been adopted by many of the
world's scientists as the new 'Benchmark Standard' for age dating (Time
Marker) of certain 'older' meteorites.

In the words of one of the top meteorite researchers, "This new "benchmark"
is relevant only for very old specimens like angrites, brachinites and CAI
that formed when Mn-53 was still alive to decay to Cr-53. Basically, NWA
4801 has replaced LEW 86010 as the point of calibration (or anchor) for
Mn-Cr ages by correlation with precise ages determined on the same specimens
with lead isotopes."

This once again illustrates that meteorites from the hot deserts of
Northwest Africa are an important part of modern meteoritics! Here is a link
to an abstract with NWA 4801 used as the new 'standard':

http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1381.pdf

Best regards,
Greg

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Received on Wed 03 Nov 2010 05:35:59 PM PDT