Article
Dating Rock Varnishes by the Cation Ratio Method with PIXE, ICP, and the Electron Microprobe
International Journal of PIXE
(1990)
Abstract
The measurement of rock varnish cation-ratios [(K+Ca)/Ti] and barium is evaluated by analyzing the same varnish scrapings with PIXE, inductively coupled plasma, neutron activation and wavelength dispersive electron microprobe. Results among these different methods are generally similar for ratios, but absolute concentrations differ in part due to uncertainties associated with weighing small samples. Barium concentrations are typically less than 1 % by weight; higher concentrations can be found in varnishes with depressions eroded into the varnish by fungi and lichens, and later infilled with aeolian detritus often including barium sulfate. Since these infilled hollows are known to produce anomalous varnish cation ratios, high barium values can, therefore, be used as an indicator that a sample is inappropriate for cation-ratio dating. The glacial chronology at Pine Creek, California, is revised in light of new data and a better understanding of variables influencing varnish chemistry.
Keywords
- Rock varnish,
- Cation-ratio dating,
- PIXE,
- Geochronology,
- Sierra Nevada,
- Moraines
Disciplines
Publication Date
June, 1990
DOI
10.1142/S012908359000013X
Publisher Statement
Copyright© 2016 World Scientific Publishing Co Pte Ltd
Citation Information
Andrew J. Bach, Ronald I. Dorn, Thomas A. Cahill, Robert A. Eldred, et al.. "Dating Rock Varnishes by the Cation Ratio Method with PIXE, ICP, and the Electron Microprobe" International Journal of PIXE Vol. 1 Iss. 2 (1990) p. 157 - 195 Available at: http://works.bepress.com/andrew-bach/9/