[meteorite-list] Re: hunting (and radiometric dating)

From: Kelly Webb <kelly_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:43 2004
Message-ID: <3ABF0647.33C8536C_at_bhil.com>

Hi, Frank,
    The method of shortfalls in short-lifed isotopes was developed to sort out
the ages of the Antarctic meteorites, which are transported, mixed and packed
together by the ice, and preserved as a kind of jumble. Since that method works
best with very old stones, it was the perfect application with stones that can
date back to almost a million years ago. It also demonstrated that the "blue
ice" finds were mixtures of widely differing ages of stones, although the whole
assemblage is much older than finds elsewhere in the non-icebox world.
    There is a second method of estimating terrestrial age by the fading of the
thermoluminescence effect with exposure on earth, but that's about all I know
about it -- that there is one. It's a real specialized technique.
    There is a huge literature on isotopic dating of meteorites, most of it
oriented to formation ages, length of time exposure in space, and so forth, but
much less work is devoted to terrestrial ages. You need access to a good huge
university library to find most of it, though.
    I think this is the point where we holler for help from Bernd Pauli...

Kelly

Frank Prochaska wrote:

> Hello all,
>
> This is a very good summary of many of the issues involved in terrestrial
> dating meteorites. I've wondered for some time whether anyone has done
> studies to try to understand the problem better, like using isotopes to
> estimate the ages of a number of known falls, or doing a sizable number of
> samples from a large strewn field where you'd presumably be looking at
> different portions of a large preatmospheric mass, etc. Does anyone on this
> list know of any studies like this?
>
> Frank Prochaska
Received on Mon 26 Mar 2001 04:05:12 AM PST