Award Date

12-1999

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Jean Cline, Chair

Second Committee Member

Margaret Rees

Third Committee Member

Wanda J. Taylor

Graduate Faculty Representative

Stephen H. Lepp

Number of Pages

163

Abstract

In this study, mineral assemblages and related fluid inclusions at the Turquoise Ridge Carlin-type gold deposit were examined to answer the following questions: (1) What is the ore-stage mineral paragenesis? (2) At what pressures and temperatures did the deposits form? (3) What are the sources of ore fluids?

Pyrite with gold, jasperoid quartz, stibnite, orpiment, realgar, and calcite were successively deposited at Turquoise Ridge. Microthermometric data and isotopic ratios of inclusion fluids in ore-related minerals indicate entrapment of multiple generations of fluids in pre-ore, ore-, and late-ore stage minerals. Primary fluid inclusions in an ore-stage jasperoid quartz crystal have salinities of 12.6 to 19 wt.% NaCl equivalent, and most inclusions homogenized between 130° and 193°C Isotopic signatures of inclusion fluids in ore-state jasperoid quartz, δD = -33[per thousand] and δ 18 O = +7.1 to +12.2[per thousand] and δD = -46[per thousand] and δ 18 O = +5.4 to +10.5[per thousand], are consistent with a magmatic or metamorphic source, or both, while inclusion fluids in late-ore stage calcite yielded δ 18 O = 10 to 14.5[per thousand] and δD = -110[per thousand], indicating trapping of an evolved meteoric fluid.

Keywords

Fluid inclusions; Gold ores -- Geology; Paragenesis; Nevada -- Turquoise Ridge

Disciplines

Geochemistry | Geology

Language

English

Comments

Signatures have been redacted for privacy and security measures.


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