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On the origin of (4)He and (40)Ar in natural goldIn a first report on our investigations of noble gases in native gold we demonstrated that placer gold contains an excess of radiogenic (4)He and (40)Ar relative to the concentrations expected from in situ decay of U, Th, and K, respectively, during the geologic age of about 30 Ma of the samples. We also showed that the U/Th-(4)He age of 36 Ma of vein-type gold from the Southern Alps agrees with its K-Ar formation age derived from associated muscovite and biotite. We now studied the question of the origin of the (4)He and (40)Ar excesses of placer gold. We conclude that gold contains two components of noble gases, a low-temperature component from fluid inclusions or phases which release noble gases at less than 800 C and a high-temperature component released when gold melts (1064 C). In some samples extremely high U and K concentrations or an unreasonably high formation age would be required to explain the observed (4)He abundances. Thus, trapped (4)He and (40)Ar must be present in gold.
Document ID
19940007768
Document Type
Conference Paper
Authors
Eugster, O. (Bern Univ. Bern, Switzerland)
Hofmann, B. (Bern Univ. Bern, Switzerland)
Niedermann, S. (Bern Univ. Bern, Switzerland)
Thalmann, CH. (Bern Univ. Bern, Switzerland)
Date Acquired
September 6, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Lunar and Planetary Inst., Twenty-fourth Lunar and Planetary Science Conference. Part 1: A-F 455-456 (SEE N94-12015 01-91)
Subject Category
METALLIC MATERIALS
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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