Path: utzoo!mnetor!uunet!wucs1!wucs2!slustl!slu70!guy
From: guy@slu70.UUCP (Guy M. Smith)
Newsgroups: sci.misc
Subject: Re: radiation dating
Message-ID: <119@slu70.UUCP>
Date: 12 Apr 88 17:45:50 GMT
References: <5236@uwmcsd1.UUCP> <1138@PT.CS.CMU.EDU> <5250@uwmcsd1.UUCP> <11009@mimsy.UUCP>
Organization: St. Louis Univ., St. Louis, MO
Lines: 15
Summary: solid rock

In article <11009@mimsy.UUCP>, chris@mimsy.UUCP (Chris Torek) writes:
> If the absolute counts of either Rubidium-87 or Strontium-87 were
> influenced by the event, the ratio function [Rb/Sr](t) might have a
The problem with this idea is that you need to insert these isotopes into
solid rock. Most geochronologists start with a large chunk of solid
unaltered (hopefully) rock and take steps to eliminate contamination
(like removing the weathering rind, etc). They then either grind
up the whole rock or they extract certain minerals (generally a better
technique). Uranium-lead dating is commonly done with zircons extracted
from the original sample (you need 50-100 kg to start). It is difficult
to see how an event of the sort under discussion could affect the
elements buried centimeters or meters below the surface of a solid
igneous rock. It would affect sediments but they are generally unsuitable
for radiometric dating. As discussed by another poster, the exception
is carbon-14 dating.