U–Th dating of single zircons from young granitoid xenoliths: new tools for understanding volcanic processes

U–Th dating of single zircons from young granitoid xenoliths: new tools for understanding volcanic processes

Multiple U–Th isotopic analyses of individual zircon crystals by ion microprobe define isochrons that discriminate between different crystallization ages of granitoid xenoliths in lavas erupted 1065 and 2000 years ago from Medicine Lake volcano, CA, USA. Zircon ages indicate at least two intrusive e...

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Bibliographic Details
Published in:Earth and planetary science letters Vol. 183; no. 1; pp. 291 - 302
Main Authors: Lowenstern, J.B, Persing, H.M, Wooden, J.L, Lanphere, M, Donnelly-Nolan, J, Grove, T.L
Format: Journal Article
Language:English
Published: Elsevier B.V 30-11-2000
Subjects:
California
geochronology
granites xenolith
ion probe data
Medicine Lake
SHRIMP data
U-238/Th-230
zircon
U-238/Th-230
geochronology
Medicine Lake
zircon
granites xenolith
California
ion probe data
SHRIMP data
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Summary:Multiple U–Th isotopic analyses of individual zircon crystals by ion microprobe define isochrons that discriminate between different crystallization ages of granitoid xenoliths in lavas erupted 1065 and 2000 years ago from Medicine Lake volcano, CA, USA. Zircon ages indicate at least two intrusive episodes, ∼25 and ∼90 ka, at times when silicic volcanism was rare, but basaltic volcanism was prevalent. Ar–Ar spectra require that the granitoids were completely crystalline thousands of years prior to their mobilization and eruption. These techniques demonstrate that individual zircon crystals can form rapidly enough to provide unique U–Th ages, and allow dating of <300 ka xenoliths from volcanic eruptions.
ISSN:0012-821X
1385-013X
DOI:10.1016/S0012-821X(00)00273-9