Award Date

1-1-2001

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Geoscience

First Committee Member

Jean S. Cline

Number of Pages

133

Abstract

Petrographic and geochemical investigations of pyrite and marcasite from the Getchell Carlin-type gold deposit show that elevated concentrations of a characteristic suite of trace metals correlate with ore-stage pyrite morphology. Secondary ion mass spectrometry analyses revealed a significant positive correlation between As and Au in ore-stage Fe-sulfide minerals. High-resolution transmission electron microscopy analyses revealed that gold-bearing Fe-sulfide crystals are arsenic-rich marcasite, rather than pyrite. These analyses failed to identify gold as microinclusions in ore-stage pyrite/marcasite, and support the conclusion that gold is present in solid solution; Analyses reflect the chemistry of fluids responsible for precipitation of the pyrite and marcasite. Near stoichiometric, pre-ore pyrite precipitated from fluids that were not saturated in Hg, Tl, As, Cu, Au and Sb. Ore-stage pyrite textures suggest rapid precipitation from fluids that contained Hg, Tl, As, Cu, Au and Sb. Late-ore stage marcasite indicates that late fluids continued to transport significant As.

Keywords

Bearing; County; Deposit; Free; Geochemistry; Getchell; Gold; Humboldt; Marcasite; Nevada; Pyrite

Controlled Subject

Geochemistry; Geology; Mineralogy

File Format

pdf

File Size

3993.6 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

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