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Scanning Electron Microscopic Analysis Of Rock Varnish Chemistry For Cation-Ratio Dating: An Examination Of Electron Beam Penetration Depths, Steven L. Reneau, Roland C. Hagan, Charles D. Harrington, Robert Raymond Jr.
Scanning Electron Microscopic Analysis Of Rock Varnish Chemistry For Cation-Ratio Dating: An Examination Of Electron Beam Penetration Depths, Steven L. Reneau, Roland C. Hagan, Charles D. Harrington, Robert Raymond Jr.
Scanning Microscopy
Rock varnish is a microns-thick manganese- and iron-rich coating that forms on exposed rock surfaces in arid and semi-arid environments, and empirical correlations of the varnish cation ratio (K+Ca):Ti with age have been used to estimate ages of geomorphic surfaces. One method of obtaining varnish chemistry for cation-ratio dating involves scanning electron microscope (SEM) energy dispersive x-ray (EDX) analysis of natural varnish surfaces. The chemical analyses of rock varnish with SEM/EDX utilize a sequence of accelerating voltages to vary penetration depths into the sample. Using elemental x-ray maps of natural varnish surfaces obtained by SEM/EDX analysis, penetration into the substrate …
Barium Concentration In Rock Varnish: Implications For Calibrated Rock Varnish Dating Curves, C. D. Harrington, D. J. Krier, R. Raymond Jr., S. L. Reneau
Barium Concentration In Rock Varnish: Implications For Calibrated Rock Varnish Dating Curves, C. D. Harrington, D. J. Krier, R. Raymond Jr., S. L. Reneau
Scanning Microscopy
Cation-ratio dating of rock varnish is a recently developed technique for obtaining surface exposure ages of a wide variety of geomorphic surfaces. As originally proposed, the technique utilizes a ratio among minor cations [(K+Ca)/Ti] in rock varnish. Although this varnish cation ratio is related to the Ti concentration, it can also be affected by the presence of Ba that may be partially included in the analyzed concentration of Ti. Barium is a minor constituent found in virtually all rock varnishes sampled from the Lake Mead area, Las Vegas Valley, and the Crater Flat region of southern Nevada. Barium is heterogeneously …