Lithologic controls on rock varnish formation as determined by SEM (scanning electron microscope)
Rock varnish is a ubiquitous, manganese- and iron-rich coating found on rock exposures in arid and semiarid regions. Recent work has demonstrated the potential for using rock varnish due geomorphic surfaces semi-quantitatively. Such dating relies on ratios of minor elements in the varnish ((Ca + K)/Ti) calculated for a specific geographic area. However, although cation-radio dating has empirically been shown to work, relationships between varnish mineralogies, varnish element contents, varnish diagenesis, and mechanism of vanish formation are not yet understood. In addition, it is not clear what effect these various varnish attributes have on the elemental ratios used in rock vanish dating. We do know, however, that the mineralogy, texture, and morphology of substrate lithologies may greatly affect initial varnish accretion. Understanding this effect may help to clarify uncertainties that now exist in the empirical varnish cation-ratio (VCR) dating technique. 8 figs.
- Research Organization:
- Los Alamos National Lab., NM (USA)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6095145
- Report Number(s):
- LA-UR-89-645; CONF-890748-1; ON: DE89008020
- Resource Relation:
- Conference: Microbeam Analysis Society meeting, Asheville, NC, USA, 16 Jul 1989; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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