Alessandra:
Basaltic glasses etch much more quickly than rhyolitic obsidians. There
are several other problems with them as well. First, they may partially
anneal at ambient surface temperatures and second, they are very low in
uranium. They will have very low fossil track densities. Dieter Storzer
has had more experience with basaltic glasses than any other fission
tracker that I know of. His address and email are in the latest ON TRACK.
Dieter was successful in dating basaltic glasses recovered from the bottom
of the ocean because the glasses were kept cold because of the temperature
at the bottom of the ocean (4°C).
The only success that I have had in dating basalts is to look for basement
inclusions in the basalt flows. The fission tracks in the apatite and
zircon in these xenoliths are usually annealed by the heat of the magma.
Chuck
Charles W. Naeser
926A National Center
U.S. Geological Survey
Reston, VA 20192
USA
Email: [log in to unmask]
phone: 703-648-6964
FAX: 703-648-6953
guglielmetti
<alessandra.guglielmetti@M To: [log in to unmask]
I.INFN.IT> cc:
Sent by: Fission track Subject: Basaltic glasses
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02/21/02 05:56 AM
Please respond to Fission
track
Dear All,
I would like to know if any of you has ever dealt with BASALTIC GLASSES.
In particular I would like to know the etching conditions. Are they similar
to those for obsidians?
Many thanks
Alessandra Guglielmetti
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