Journal ArticleDOI
An evaluation of the uranium‐thorium‐helium method for dating young basalts
TLDR
In this paper, a comparison of K-Ar and ages based on U-Th-He on young basalts from the San Francisco Volcanic Field near Flagstaff, Arizona, showed that approximately one fifth of the He is retained and thus U-th-He ages are too young.Abstract:
Comparison of K-Ar and ages based on U-Th-He on young basalts from the San Francisco Volcanic Field near Flagstaff, Arizona, shows that approximately one fifth of the He is retained and thus U-Th-He ages are too young. Leaching with weak acid produces large losses of U in only a few minutes, which suggests that He is lost from surficial positions on minerals from radiation damage sites and from interconnecting crystal defects. One sample of large plagioclase phenocrysts showed excess He. It seems unlikely that the U-Th-He method can be used to obtain reliable ages on young basalts. (auth)read more
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Journal ArticleDOI
(U-Th)/He Dating: Techniques, Calibrations, and Applications
TL;DR: Theler and coworkers as mentioned in this paper proposed that in the case of apatite, He ages might be interpreted as ages of cooling through very low temperatures, a value that was supported by more recent studies.
Journal ArticleDOI
U-Th-He dating of apatite: A potential thermochronometer
TL;DR: In this article, a gem quality crystal of Durango fluorapatite was found to have a 4He content consistent with complete retention of radiogenic helium since its formation at about 31 Ma.
Journal ArticleDOI
Diffusion of cosmogenic3He in olivine and quartz: implications for surface exposure dating
TL;DR: In this paper, the authors measured cosmogenic3He diffusivities in quartz and olivine by incremental heating at 150-600°C and concluded that helium loss will not significantly affect Cosmogenic 3He exposure dating.
MonographDOI
Diffusion of Helium Isotopes in Silicate Glasses and Minerals: Implications for Petrogenesis and Geochronology.
TL;DR: In this article, the authors measured isotopic diffusivity ratios, D3He/D4He, are not compositiondependent, average 1.08±.02, and vary slightly with temperature, consistent with an activation energy difference of 60±20 cal/mole.
References
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Journal ArticleDOI
Cracks and Pores: A Closer Look
TL;DR: Most pores and some cracks in several rocks, as directly viewed with a new technique, have a shape that suggests an origin early in the history of these rocks, which may be a reliable indication of behavior in the earth's crust, for electrical resistivity, permeability, or other properties that depend on microporosity.
Journal ArticleDOI
Potassium-Argon Dating of Holocene Basalts of the Honolulu Volcanic Series
TL;DR: In this article, the potassium-argon method of geo-chronometry has been modified to enable the dating of young, normal volcanic rocks, which has been applied to date the posterosional volcanics of the Honolulu Series, which include such well-known Hawaiian landmarks as Diamond Head and Punchbowl.
Journal ArticleDOI
Potassium-Argon Ages from the Pololu Volcanic Series, Kohala Volcano, Hawaii
TL;DR: Potassium-argon ages on five lava flows from the Pololu Volcanic Series, thought to be among the oldest rocks exposed on the island of Hawaii, indicate that the main subaerial shield-building phase of Kohala Volcano occurred about 0.7 ± 0.15 m.y..
Journal ArticleDOI
Helium-uranium dating of corals.
TL;DR: Fanale and Schaeffer (1965) determined He/U ages of corals and other aragonitic fossils, and found that the results generally agreed with independent age estimates as mentioned in this paper.
Journal ArticleDOI
The distribution of thorium and uranium in a pennsylvanian weathering profile
R. Pliler,John A. S. Adams +1 more
TL;DR: In this article, 11 samples representing a pre-Pennsylvanian weathering profile on the Boulder Creek granodiorite near Boulder, Colorado, have been analyzed for thorium and uranium by γ-ray spectrometric and chemical methods.