Apologies for multiple posting!
Dear all,
I am a casual applicant of U-Pb zircon
geochronology, having just dated zircons from
various granites and gneisses in the Pyrenees.
Two of my samples, both Variscan (ca. 335 Ma)
leucogranites, contain short prismatic,
yellow-brownish zircons, with a rather high
U-content: 2000-6000 ppm. What puzzles me is the
internal texture of these zircons, revealed by CL
imaging. While the rims show thin ocsillatory
zoning, the central part has a very patchy
appearance. Can this be damage caused by the high
U-content? If so, it could explain the relatively
low percentage of concordant ages, compared to
zircons of the other samples. Is there any
special term for this texture? I have looked into
the literature, but did not find any comparable appearances.
Thanks for any suggestions,
Jochen
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Dr. Jochen Mezger
Lehrbeauftragter - Lecturer
Allgemeine Geologie
Martin-Luther-Universität Halle-Wittenberg Tel.: 49-0-345-5526120
Institut für
Geowissenschaften Fax: 49-0-345-5527220
Von-Seckendorff-Platz 3
06120 Halle Email: [log in to unmask]
GERMANY
http://www.geologie.uni-halle.de/igw/allgeo/staff/mez.html
http://allgeo.geologie.uni-halle.de/mitarbeiter/jmezger/
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"Vous etes des assassins ! -
You are murderers !" Octave Lapize,
winner of the 1910 Tour de France
at the summit of the Tourmalet, Pyrenees
to Henri Desgranges, organizer of the Tour
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