[meteorite-list] fundamental processes of meteorite formation

From: Robert & Wendi Beauford <wendirob_at_meteoritecentral.com>
Date: Thu Apr 22 09:49:01 2004
Message-ID: <01a101c13fbd$bd1f52c0$854897cc_at_wendirob>

> One of the most puzzling aspects of the ureilites is that the oxygen
isotopes fall along a line with a slope of 1. That means they have
undergone very little to no fraction since they were pulled from the nebula.
Because Venus is a differentiated planet, the isotopes should have been
fractionated.
> Steven Singletary

If anyone would be so kind as to take a moment to help me understand this, I
would be greatly appreciative. First, why does the process of
differentiation or presence on a differentiated body bring about
fractionation in isotopes that is different than that found in the same
elements on undifferentiated bodies? (I know this is an ignorant question,
but I'm trying... I really am.)
Second, I assume that the nebula mentioned is the dust cloud associated with
the formation of our solar system. What was the origin of this nebula dust
material? Was it from various supernovas or similar events? If so, is this
'preprocessing' why it was high enough in heavy radioactive elements to
create a solar system and planetary masses that then took billions of years
to cool?
And another not directy related question regarding a different class of
meteorites, chondrites. The dust that makes up the matrix between
chondrules,... how similar is it to interplanetary dust today, and what
caused some of it to bunch up as chondrules and some of it to remain loose
to form the matrix? How much does the dust differ in makeup from the
chondrules (by this I mean was the process of chondrule formation selective,
and how much did the processes that lead to chondrule formation alter the
materials involved. Was it just a 'slow' clumping due to gravity, or was it
affected by the heat processes of the early solar nebula?) And.... the metal
flakes in chondrites... what determined their size distribution?
Thanks for your knowledge on any of these questions that you might be
willing to take the time to help me out with.
-Robert Beauford : )
Received on Mon 17 Sep 2001 05:12:43 PM PDT