For meteorites exposed a long time in deserts, one of the processes
is ablation or abrasion by the wind - sand-blasting. Omanian lunars
seldom have fusion crusts. Look at the Dhofars 461 and 465 here:
http://meteorites.wustl.edu/lunar/stones/dhofar0026.htm
If you handed those rocks to a geologist, she'd say, on the basis of
the 3-sided shapes, "those are ventifacts," not, "those are
meteorites." Omanian meteorites have been getting smaller with time!
http://en.wikipedia.org/wiki/Ventifact
Scientists who've studied the Dar al Gani field in Libya say that one
of the reasons for the preservation is that the wind-blown sand is
from carbonate rock (soft), not quartz (hard). The meteorites in the
Dhofar photos above appear to be sitting on carbonate desert
pavements, but I have to conclude that there's a source of quartz
sand somewhere.
Even in Antarctica, meteorite fusion crust is lost to wind ablation,
even though there's little sand in the wind. All meteorite
collection places in Antarctica are places where the katabatic winds
are blowing so hard that snow does not accumulate and the ice is
being ablated by the wind at the rate of a few inches per year.
At 12:04 2009-09-11 Friday, you wrote:
You will probably think I am a bit off the latch with this question
but here goes anyway... In the world of meteorite terminology, is
there a term or word which describes the loss of fusion crust (by
forces of nature) from stony meteorites. 'Spalling' possibly? The
loss of crust, part or all, seems to be a rather common occurrence
especially for some of the more friable stonys. With the crust gone,
the stone is 'denuded'?
Mike in CO
Randy Korotev
Saint Louis, MO
koro...@wustl.edu
______________________________________________
http://www.meteoritecentral.com
Meteorite-list mailing list
Meteorite-list@meteoritecentral.com
http://six.pairlist.net/mailman/listinfo/meteorite-list
