The Cretaceous Merín aborted-rift basin of eastern Uruguay is composed of sub-alkaline Paraná-Etendeka province basaltic flows and shallow intrusives (~133 to 131 Ma), rhyolitic ignimbrites (~130 to 128 Ma) and associated mildly alkaline to alkaline intrusions and volcanic rocks (~128 to 127 Ma). Four intrusive complexes from 20 to >30...
The Lights Creek Stock is an 18 square kilometer copper-bearing granitoid
intrusion within the Plumas Copper Belt in the northern California Sierra Nevada. Engels
Mine, Superior Mine, and Moonlight Valley represent the main copper-mineralization in
the Lights Creek district and small prospects include the Ruby Mine, and Moonlight
Creek. The...
The detection of subtle variations in mineral chemistry in zoned hydrothermal
alteration associated with the formation of porphyry copper deposits by short-wave
infrared spectroscopy and rock chemistry are potentially valuable vectoring tools for
mineral exploration. In order to correctly interpret the data collected by these methods,
results must be calibrated...
Oxidized hydrous intermediate composition magmas are responsible for porphyry copper (Cu ±Mo ±Au) deposits and epithermal Au ore deposits formed globally in the shallow crust (Sillitoe, 2010; Seedorff et al., 2005). Recently, zircon geochemistry has been used to characterize both productive and barren intrusions associated with porphyry Cu-Au ore deposits....
The Pebble porphyry Cu-Au-Mo deposit in Alaska is one of the world's largest Cu-Au mineral resources. Late Cretaceous magmatic evolution in the Pebble district culminated with the intrusion of the Kaskanak Batholith and associated porphyry copper-gold-molybdenum mineralization. The Kaskanak Batholith is a multiphase granodiorite intrusion with an estimated footprint of...
The Emigrant Pass volcanics (EPV) are a 38.3 to 36.4 Ma calc-alkaline volcanic center that erupted andesite and dacite, and a late series of felsic dikes along the south flank of the Carlin gold district in north-central Nevada. The EPV includes dacite and rhyolite porphyry dikes indistinguishable from porphyry dikes...
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...
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...
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...