New approaches to quaternary geochronology: U-Th/He dating of basalt and stable isotope mapping of polar glaciers
- Author:
-
Aciego, Sarah Maria
- Title:
- New approaches to quaternary geochronology: U-Th/He dating of basalt and stable isotope mapping of polar glaciers
- Periodical:
- Geology
- Year:
- 2006
- Volume:
- Ph.D.
- Pages:
- 186
- Subject:
-
Uranium-thorium dating
Helium
Quaternary
Geochronology
Basalt
Stable isotope
Glaciers
Radioactivity measurement
Radioactive dating
- Summary:
- This work demonstrates two dating techniques that can be applied to the Quaternary period: the U-Th/He radiometric method and stable isotope mapping of glacial ice. The investigation of the U-Th/He method followed a progression from initial testing on a sample of known age to application of the technique to basalt samples of unknown age in Idaho and Hawaii. The second experiment involved measurements of minerals with low U and Th concentrations and included measurement of U, Th, and He concentrations on the same sample aliquot, comparison of the U-Th/He and U-Th disequilibrium techniques, and the concurrent determination of the U-Th/He age and He-3 cosmogenic exposure ages on the same samples. Olivine phenocrysts from basalt lavas of the Snake River Plain, Idaho, and Mauna Kea volcano, Hawaii were used for this study. Post-shield lavas from Mauna Kea were analyzed to probe the limits of the U-Th/He technique on samples with low U and Th concentrations. The U-Th/He ages conform to the stratigraphy and previously published C-14 and K-Ar ages.
- Date:
- Fall 2006
- Collection:
- Monographs