Obsidian hydration profile measurements using a nuclear reaction technique
Abstract
Ambient water diffuses into the exposed surfaces of obsidian, forming a hydration layer which increases in thickness with time to a maximum depth of 20-40 μm (ref. 1), this layer being the basic foundation of obsidian dating. We have used the resonance at a ^(19)F energy of 16.45 MeV (0.83 MeV centre-of-mass energy) (ref. 4) in the nuclear reaction ^1H(^(19)F,ɑy)^(16)O to measure directly the hydration profiles of obsidian samples. This technique has already been used to measure the hydrogen concentration profiles in lunar samples and other solids to depths up to 0.4 μm with a resolution of 0.02 μm (refs 5 and 6). A second strong resonance at 17.64 MeV is encountered in extending these measurements to greater depths but its contribution can be unfolded from the data.
Additional Information
© 1974 Nature Publishing Group. Received December 27, 1973; revised April 9, 1974. We thank Dr D. S. Burnett for suggesting the application of this nuclear reaction technique to obsidian hydration measurements, and R.H. Goldberg and W. Long for technical assistance. We also thank Dr J. O'Keefe, NASA, for the tektite samples and Dr C. W. Meighan for the hydration measurements through the Obsidian Hydration Laboratory, Department of Anthropology, University of California, Los Angeles. This work was supported in part by the National Science Foundation.Additional details
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- CaltechAUTHORS:20150903-132323681
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2015-09-03Created from EPrint's datestamp field
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2021-11-10Created from EPrint's last_modified field