Award Date

1-1-2000

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Jean S. Cline

Number of Pages

148

Abstract

Samples of banded veins, microcrystalline quartz veins, and hydrothermal breccias +/- Au in the southern Castle Mountains, California were collected from four different zones within and up to 5 km outside the mine area in order to construct a paragenesis, interpret fluid origin, describe the thermal history, and examine fluid inclusion gas compositions as an exploration tool for low-sulfidation deposits. Two-thirds of the gold from the Lesley Ann deposit is associated with pyrite, found in zones of intense silicification, and precipitated due to sulfidation of rhyolitic host rock during the earliest stages of hydrothermal activity. The remaining gold occurs freely in breccia matrix quartz and was deposited after silicification as a result of cooling and boiling of 200 to 240°C fluids with 0 to 0.2 wt % NaCl equivalent. Late banded quartz and drusy quartz precipitated in all areas from 150 to 185°C waters with 0 to 1.1 eq wt % NaCl equivalent. Chalcedony bands adjacent to quartz in barren banded veins north of the mine area represent temperature drops likely resulting from abrupt changes in boiling zone levels, evidenced by platy calcite textures found in a few, but not all, quartz bands. (Abstract shortened by UMI.).

Keywords

California; Epithermal; Fluid; Gold; History; Low; Origin; Paragenesis; Silver; Sulfidation; Systems; Thermal

Controlled Subject

Geology; Municipal engineering; Sanitary engineering; Chemistry, Analytic; Geochemistry

File Format

pdf

File Size

4249.6 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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