Genetic, spectral, and Landsat thematic mapper imagery relatonships between desert varnish and Tertiary volcanic host rocks, southern Nevada
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Authors
Spatz, David Moore
Issue Date
1988
Type
Dissertation
Language
en_US
Keywords
Desert Varnish , Volcanic Rock Assemblages , Nevada , Iron , Manganese , Silica , Alumina Rich Amorphous Compounds , Scanning Electron Microscope Observation , Varnish Encrustations , Varnish Laminations , Tertiary Volcanic Host Rocks , Mackay Theses and Dissertations Grant Collection
Alternative Title
Abstract
Desert varnish on volcanic rock assemblages of southern Nevada is composed largely of iron, manganese, silica, and alumina rich amorphous compounds. Thin section and scanning electron microscope observation reveals that desert varnish occurs chiefly as thin discontinuous translucent films that impregnate rock surfaces intergranularly to depths typically of o. 1-0. 3mm. Varnish encrustations and laminations are less common and tend to concentrate in minute recesses. Manganese is commonly concentrated at the coating-air interface and within coating interlayers. Iron exhibits more consistent background levels but is often concentrated at the coating-rock interface. Higher iron/manganese ratios and total combined iron and manganese in coatings on mafic rocks, and high cerium levels in coatings on rocks enriched in cerium and other rare earth elements, suggest a genetic relationship with underlying host rocks.
Description
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Citation
Publisher
University of Nevada, Reno
License
In Copyright(All Rights Reserved)