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- Title
Helium isotope disequilibrium and geochronology of glassy submarine basalts.
- Authors
Graham, David W.; Jenkins, William J.; Kurz, Mark D.; Batiza, Rodey
- Abstract
The (U+Th)/He dating method is the oldest method of geochronology that involves radioactivity, but historically it has not been particularly successful. Even when problems of poor helium retention and loss due to radiation damage are circumvented by analysing suitable mineral phases1-4, problems frequently remain with inherited helium5,6. Here we show that isotope disequilibrium in the 3He/4He ratio between helium trapped in vesicles and that dissolved in the glass phase of some young seamount basalts can be used to determine (U + Th)/He ages for the basalts. We use the 3He/4He in vesicles (extracted by crushing in vacuo) to correct the dissolved phase He (by fusion of the remaining powder) for the inherited component, and compute the radiogenic helium concentration. The method is applicable to rocks containing phases with different (U+Th)/He, and the results have implications for dating lavas in the age range of 103 to 106 years (thus filling a gap between the limits of the 14C and K-Ar methods), and for reconstructing the geochemical history of young volcanic systems.
- Publication
Nature, 1987, Vol 326, Issue 6111, p384
- ISSN
0028-0836
- Publication type
Article
- DOI
10.1038/326384a0