The Hopper property is located in the Yukon Tanana terrane in the southwestern Yukon. It is characterized by granodiorite-hosted copper and molybdenum mineralization that is related to propylitic alteration and shearing. The focus of this study is to develop a genetic model for the copper mineralization based on field, petrographic and geochemical analyses. The mineralization zone is roughly 500 m long and 20 m wide and is hosted in a granodiorite of calc-alkaline affinity interpreted to be part of the Ruby Range batholith which intruded the Aishihik metamorphic suite. The intrusion took place during the late Cretaceous based on U and Pb analyses of zircons with laser ablation inductively-coupled plasma mass spectrometer, placing it in the same time frame as the intrusion hosting the Casino mineralization, the largest porphyry copper deposit in the Yukon. The mineralization consists of chalcopyrite and molybdenite found along fractures, as disseminations and on shearing surfaces. Sulphur isotopes from chalcopyrite and pyrite range from -1.7 to -0.8 per mil suggesting it is ortho-magmatic in origin. The chemical compositions of biotite and amphibole of the Hopper intrusion resemble mineral chemistry of known porphyry systems. Biotites from both Hopper and Casino exhibit Mg-Cl avoidance and have similar values of MnO, TiO2, Al2O3, BaO, Na2O and K2O, and amphiboles range in composition between magnesio-hornblende and actinolite, similar to other porphyry copper type deposits. There are two distinct populations of titanite in the Hopper intrusion, magmatic and hydrothermal. Magmatic titanites are euhedral and are in sharp, planar contact with other magmatic phases, whereas hydrothermal titanites are anhedral and are associated with alteration minerals and the mineralization. Both populations show substitution between Ti and Al+Fe+Nb+Zr+Ce+Y. The hydrothermal titanites are richer in Ti, Cu, and Cr compared to the magmatic ones that are more enriched in Mo suggesting the mineralization is ortho-magmatic in origin. Sulphur isotopes analyses suggest Hopper could be a porphyry type mineralization. However, the mineralization was also found to be related with propylitic alteration, shearing and depletion in Si and K, indicating this is not a typical system. Therefore, two possible models can explain the copper occurrence at Hopper. According to the first model, the mineralization is ortho-magmatic and is part of a porphyry system, but it has been remobilized to the propylitic zone. A second model is that the mineralization is much younger than the intrusion and is related to shearing.

The Neoplatonist philosopher Porphyry of Tyre (ca.232-305 A.D.) wrote Against the Christians, a fifteen-volume treatise targeting Christianity. Porphyry's attack was considered so scandalous that it was twice condemned to flames by Roman emperors. It is thus only in the works of Christian apologists that Against the Christians is extant, i.e. in a fragmentary state. The topic of this study is the twelfth book of Porphyry's treatise, the best known and probably the most challenging to Christians. Indeed, it deals with the Book of Daniel, which underlies a great part of Christianity's foundations as it allegedly foretells both Parousiai. It will first be demonstrated that the writing of the treatise can be dated to the 290s, which indicates it was not an immediate threat to Christians facing the Great Persecution (303-311). Then recent methodological approaches are presented in order to get a better insight of the content of Against the Christians. It is established that Porphyry wrote a detailed exegesis of Daniel with the intention of criticizing the Christian literal interpretation of the Scriptures by adapting history to prophecy. Finally it is suggested that Porphyry wrote his treatise in response to a Christian allegorical exegetical tradition of Daniel.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 226-240). Also available on the World Wide Web.

Multiple generations of normal faults dismembered, tilted, and exposed thicknesses of up to 15 km of the upper crust in portions of central and southern Arizona. This extension, variable in distribution and magnitude, was superimposed on the axis of the Laramide magmatic arc and dismembers many porphyry copper systems, allowing for detailed study of vertical and lateral zonation of alteration around these centers. This study examines tilted fault blocks containing portions of porphyry systems across Arizona, focusing on hydrothermal alteration deep and distal in these systems (3+ km paleodepth) to develop a more complete understanding of porphyry occurrences as larger geochemical systems. This study focuses on Na-Ca and coarse muscovite alteration in the roots of Laramide porphyry copper systems across Arizona (Ajo, Sierrita, Kelvin-Riverside, Mt. Grayback, Granite Mountain, Charleston, Globe-Miami, Sycamore Canyon, Copper Basin, Texas Canyon, and Copper Creek), provides a detailed study of Middle Jurassic coarse muscovite alteration at Luhr Hill in the Yerington district, Nevada, and documents the structural and hydrothermal evolution of the Ajo mining district in southwestern Arizona. Most areas in this study are interpreted to be highly extended, highly eroded, or both, allowing for study of deep hydrothermal alteration. Na-Ca alteration has been previously documented extensively along the Jurassic arc of the southwestern United States but less widely known in younger plutons, notably of Laramide age in Arizona. Coarse muscovite alteration previously has rarely been documented in porphyry copper systems, and this study shows that coarse muscovite alteration is likely present in systems where root zones are exposed at surface. Na-Ca alteration also is present in many in Laramide porphyry systems, though volumetrically minor, as no Laramide system contains more than a few volume perfect Na-Ca alteration in a given hydrothermal system. Na-Ca alteration in Laramide systems can include Ca, Na-Ca and Na alteration but is dominated by Na alteration (epidote-albite-chlorite ± actinolite). At Ajo, both Na-Ca and coarse muscovite alteration are present within the district due to superposition of temporally unrelated hydrothermal alteration, coupled with complex extensional deformation. This study shows that both Na-Ca and coarse muscovite alteration are more common in Laramide porphyry copper systems than previously recognized, that Na-Ca alteration is most commonly developed as shallower Na alteration (albite-epidote-chlorite ± actinolite), common deeper Na-Ca alteration (oligoclase-actinolite-epidote), and rare, deep Ca alteration (oligoclase-diopside-actinolite ± garnet ± epidote). Na-Ca alteration is commonly less voluminous in Laramide systems than documented in systems along the Jurassic arc. Coarse muscovite alteration, commonly termed greisen, occurs structurally below and commonly postdates potassic alteration and likely formed from late-stage, low-temperature, magmatic-hydrothermal fluids. Coarse muscovite alteration associated with more silicic magmatic compositions is developed at shallower depths and contains muscovite with higher trace element contents, coarse muscovite alteration with more variable mineral assemblages, and coarse muscovite veins that are better mineralized. Coarse muscovite alteration (greisen) occurs as the main mineralized veins at the tops of evolved metaluminous to peraluminous granites in W-Sn systems, as well mineralized veins in the cores and tops of Mo-Cu porphyry systems, and as poorly mineralized veins in the roots of porphyry copper systems. Detailed understanding of coarse muscovite alteration in a given district can, therefore, can be an indicator of depth or petrologic affiliation of a system. These results provide a better understanding of late-stage magmatic-hydrothermal alteration and hydrothermal alteration associated with the incursion of external fluids into the root zones of porphyry copper systems.

It has been established that porphyry copper/copper-gold deposits have formed from I Ma to 2 Ga ago. Generally, they are related to the Mesozoic-Cenozoic interval with few reported occurrences from the Palaeozoic or Precambrian. A reason cited is the erosion of these deposits which are often related to convergent plate margins and orogenic belts. Observations of the alteration and mineralisation within and around porphyry copper/copper-gold systems have been included in numerous idealised models. These alteration and mineralisation patterns are dependent on the phases of intrusion, the tectonic setting and rock type, depth of emplacement and relationship to coeval volcanics, physiochemical conditions operative within and surrounding the intrusive and many other mechanical and geochemical conditions. Island arc and cratonic arc/margin deposits are generally considered to be richer in gold than their molybdenum-rich, intra-cratonic counterparts. Metal zonation may occur around these copper/copper-gold deposits, e.g. copper in the core moving out to silver, lead, zinc and gold. This zonation is not always present and gold may occur in the core, intermediate or distal zones. Examples of gold-rich porphyry deposits from British Columbia, Chile and the SW Pacific Island regions suggest gold is closely associated with the potassic-rich zones. Generally these gold-rich zones have greater than 2% magnetite and a high oxygen fugacity is considered to be an important control for gold deposition. High Cl contents within the magma are necessary for gold mobility within the host intrusive centres. Beyond this zone HS₂ becomes an important transporting ligand. Exploration for porphyry copper-gold deposits includes an integrated geological, geophysical and geochemical approach. Petrographic work through to Landsat imagery may be used to determine the chemical conditions of the system, ore association, favourable structural zones and alteration patterns, in order to focus exploration activities.

The super-giant Oyu Tolgoi porphyry copper-gold deposits in the South Gobi desert, Mongolia, consist of multiple discrete porphyry centers aligned within a north-northeast trending, >6.5 km long, arc-transverse mineralized corridor. The porphyries are linked to a tectono-magmatic event at ~372 Ma within a Devonian to Carboniferous volcanic arc, and U-Pb (zircon) geochronology records magmatic activity from ~390 Ma to ~320 Ma. The Oyu Tolgoi district underwent at least three discrete periods of syn- to post-mineral shortening and there is evidence for at least three unconformities within the Paleozoic sequence. Although the deposits were formed in an active orogenic environment characterized by rapid uplift, their preservation is a reflection of climactic effects as well insulation from erosion by rapid burial under mass-wasted and pyroclastic material in the volcaniclastic apron of late-mineral dacitic volcanoes. The porphyry copper-gold deposits are spatially and temporally related to medium- to high-K calc-alkaline quartz monzodiorite (~372 Ma) and granodiorite (~366 Ma) intrusive phases that comprise the Late Devonian Oyu Tolgoi Igneous Complex (OTIC). Adakite-like wholerock compositions as well as zircon grains with high CeN/CeN*, EuN/EuN* and Yb/Gd in the sample populations from syn- and late-mineral porphyry intrusions are different from younger intrusions that are not related to porphyry Cu-Au deposit formation. Moreover, mixed zircon populations within OTIC intrusions indicate that efficient assimilation of material from different host rocks by a convecting magma chamber occurred. Mafic to intermediate volcanic units evolved from tholeiitic to calc-alkaline compositions, which is interpreted to be a reflection of marine arc maturation and thickening. Felsic rock suites are dominantly high-K calc-alkaline, regardless of age. Nd-isotopic geochemistry from all suites is consistent with magma derivation from depleted mantle in an intra-oceanic volcanic arc and lead isotopic compositions indicate that the sulfides in the porphyry Cu-Au deposits are genetically linked to the Late Devonian magmas. Magma mixing, adakite-like magmatism and rapid uplift and erosion in a juvenile marine arc setting differentiate the ore-stage geologic environment at Oyu Tolgoi from other settings in active and fossil volcanic arcs. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

No description available.

No description available.

<p> Three conformable units of fine-grained quartz-feldspar porphyry were mapped in the Berry River Formation, Warclub Group, Northwestern Ontario. The largest unit (Unit 1) is compared geochemically and petrographically to quartz-feldspar porphyry intrusions and tuffs in the area with the aim of determining the method of emplacement of the porphyry unit (Unit 1), and consequently the other two units.</p> / Thesis / Bachelor of Science (BSc)

Thesis (M.S.)--Oregon State University, 2006. / Printout. Includes bibliographical references (leaves 36-39). Also available on the World Wide Web.