Magmatic sulfides from Yerington, Nevada, and Yanacocha, Peru, were analyzed by laser ablation-inductively coupled mass spectrometry (LA-ICPMS) and electron microprobe to determine copper, gold, and silver concentrations and ratios in order to examine the relationship to the metal content of related magmatic-hydrothermal ores. The magmatic sulfides occur in plutonic rocks...
The Botija Cu-Mo-Au porphyry deposit is located in the Cobre Panamá mining district, which contains several deposits with a global measure and indicated and inferred resource of 14.8 MT of Cu. These deposits are associated with the Cerro Petaquilla batholith, which has U/Pb zircon ages of 26-33 Ma (Whattam et...
The El Salvador porphyry copper deposit in the Indio Muerto district of northern Chile has been geologically investigated for more than 60 years and provides one of the best bases for understanding similar environments of ore formation elsewhere in the world. Fourteen new zircon U/Pb isotopic ages obtained via in...
The interaction of magma with continental crust at convergent margins is fundamental to
understanding if and how continents grow. Isotopic and elemental data constrain the
progressive stages of development of the magmatic underpinnings of the long-lived
Aucanquilcha Volcanic Cluster (AVC), situated atop the thick continental crust of the
central Andes...
This dissertation is informally divided into three major sections. In the first section (Chapter 2) I use data from field mapping, isotopic geochronology, whole rock geochemistry and trace element concentrations in zircons to examine the petrology, geochemistry and ages of the Haquira East porphyry copper deposit of southern Peru. In...
The Inmaculada Mine is located in the Miocene belt of epithermal deposits that extends from southern Peru to northern Chile and Bolivia. This belt is known for its silver-rich epithermal veins that have been worked since colonial times. The Inmaculada Mine belongs to a mining district that includes, from north...
This dissertation is divided into two major chapters. The first chapter covers the geologyof the Encuentro deposit with emphasis in the intrusion sequence, vein mineral assemblages and distribution, and age of mineralization. The data used for this section includes field mapping, petrography, elemental analysis of biotite, and isotopic geochronology. The...
This dissertation is concerned with the behavior of sulfur in intermediate-silicic arc magmas associated with subduction at convergent margins. In particular it focusses on oxidized, sulfur-rich magmas, the conditions at which they might reach sulfate saturation, and implications of sulfate saturation. It is divided into an investigation of natural samples...
The volcanic (~45-10 Ma) and plutonic rocks (~37-12 Ma) comprising the Western Cascades extend from northernmost California to southern British Columbia and are ancestral to modern arc magmatism. The ancestral arc hosts a series of small plutons that are locally associated with porphyry (Cu-Mo) and epithermal (Au) ore deposits. Three...
The Yanacocha Mining District in northern Perú is considered the largest group of
high-sulfidation style epithermal gold deposits in the world. District-scale geologic mapping coupled with detailed 40Ar/39Ar geochronology, geochemistry and petrography establish the volcanic history of the area and analyze the temporal and spatial evolution of volcanism, hypogene advanced...