Re: [asa] Denver RATE Conference (Thousands...Not Billions)_Part 4

From: Steven M Smith <smsmith@usgs.gov>
Date: Tue Oct 09 2007 - 11:37:39 EDT

Concerning the RATE explanation on the origin of Polonium halos, David
Campbell wrote:

>>It is an improvement that they are rejecting Gentry's denial of
hydrothermal alteration. Gentry's version in which all granite is
from the creation of the earth also clashes with a lot of flood
geology if one takes cross-cutting, etc. seriously-it would entail
something a lot closer to Gosse with general appearance of age
than is popular in current YEC circles. <<

When listening to the RATE scientists, you would think that they had come
up with this hydrothermal solution to Gentry's Po halos.

  "Thus neither the Po radiohalos nor the granitic rocks
   could have been formed by fiat creation. Instead, a
   model is proposed in which hydrothermal fluids
   separated 222Rn and the Po isotopes from their
   parent 238U in zircons and transported them very
   short distances along cleavage planes in the host, and
   adjacent, biotites until the 222Rn decayed and the Po
   isotopes were chemically concentrated into
   radiocenters, there to subsequently produce the Po
   radiohalos." (Andrew Snelling, Radiohalos - A Tale
   of Three Granitic Plutons: Presented at the Fifth
   International Conference on Creationism, August 4-8, 2003
  (http://www.globalflood.org/papers/2003ICCradiohalo.html)

Yet, as David points out, Gentry denied the hydrothermal fluids
explanation for Po halos. This was back in the 1970's when he first
proposed that Po radiohalos were evidence for a young earth. In one of a
series of letters concerning Gentry that were published in the American
Geophysical Union journal EOS (1979-80), Derek York pointed out that a
hydrothermal-fluids explanation had been proposed many years before Gentry
had even begun looking at Po halos.

  "In his discussion, Henderson [1939] emphasized one
   extremely important aspect about the mode of occurrence
   of Po halos. Henderson and Sparks [1939]
   observed that while many Po halos occur with their
   central nuclei randomly located within the cleavage
   planes of micas, many others are strung together along
   obvious channels or microconduits in the cleavage
   planes. Here was the clue. Evidently, said Henderson, at
   some unknown time after crystallization, uranium-bearing
   hydrothermal solutions had been moving slowly
   through the rocks, penetrating and flowing through the
   tiny conduits. In these solutions, the uranium was supposed
   to be in equilibrium with its daughter products.
   That is, in particular, Po isotopes would also be present
   in solution. Suppose that at various points along such
   channels the chemical conditions were such that Po
   would precipitate from solution but alpha-emitting earlier
   members of the uranium chain would not. Then pointlike
   accumulations of Po would start to build up at these
   nuclei. The precipitated Po would almost immediately
   decay and halo formation would have begun. Meanwhile,
   more Po would precipitate from solution at these
   Po centers and a halo would eventually be produced.
   Henderson discussed the details of this process in
   terms of order of magnitude of flow rates and concentrations.
   To explain the Po halos of random occurrence,
   one merely had to postulate that the solutions
   permeated the micas along whole cleavage planes, not
   solely along channels. (Derek York, Polonium Halos and
   Geochronology, EOS, vol. 60, no. 33, August 14, 1979,
   page 617)

Thus we see that the hydrothermal solution to Po halos was first proposed
by Henderson in 1939. Perhaps, congratulations are in order. RATE
research has advanced the YEC science of radiohalos up to 1939. As David
said, this is an improvement.

Steve
(Disclaimer: Opinions expressed herein are my own and are not to be
attributed to my employer ... or anyone else.)
_____________
 Steven M. Smith, Geologist, U.S. Geological Survey
 Box 25046, M.S. 973, DFC, Denver, CO 80225
 Office: (303)236-1192, Fax: (303)236-3200
 Email: smsmith@usgs.gov
 -USGS Nat'l Geochem. Database NURE HSSR Web Site-
  http://pubs.usgs.gov/of/1997/ofr-97-0492/

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Received on Tue Oct 9 11:40:41 2007

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