Geology and hydrothermal alteration of the Palmetto property, Esmeralda County, Nevada
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Authors
Wolverson, Nancy Jean
Issue Date
1987
Type
Thesis
Language
en_US
Keywords
Hydrothermally Altered Andesite Lava , Hydrothermally Altered Dactite Lava , Precious Metals , Paleozoic Sedimentary Rocks , Palmetto Property , Volcanic Rocks , Alteration Envelopes , E-w-trending Silica+alunite Ribs , Argillically Altered Rocks , Propylitized Rocks , Quartz+alunite , Cristobalite+alunite , Sulfur Isotopic Determinations , Coarsegrained Alunite , Pyrite , Hypogene , Supergene , Gold , Zone Of Oxidation , Hydrothermal Breccias , Adularia , Sulfate Minerals , Ore , Mackay Theses and Dissertations Grant Collection
Alternative Title
Abstract
Hydrothermally altered andesite/dacite lavas containing detectable precious metals and largely unaltered Paleozoic sedimentary rocks are exposed at the Palmetto property. Within the volcanic rocks alteration envelopes are centered on prominent E-W-trending silica+alunite ribs in sharp contact with argillically altered rocks that grade outward into propylitized rocks. The ribs vary from quartz+alunite in the north to cristobalite+alunite in the south. Sulfur isotopic determinations suggest coarsegrained alunite (£34S = 23.5 per mil) and pyrite (^34S = 3.7 per mil) are hypogene, whereas fine-grained alunite (£34S=0.7 per mil) is supergene. The hypogene alunite has a K-Ar age of 16.1+0.7 m.y. Gold increases below the zone of oxidation with the appearance of approximately 1% pyrite. Based on the presence of hydrothermal breccias and adularia and the abundance of sulfate minerals, boiling probably occurred. The lack of repeated boiling episodes may explain the absence of ore.
Description
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Citation
Publisher
University of Nevada, Reno
License
In Copyright(All Rights Reserved)