Download or read book Geology of Wall rock Alteration Mineralization and Metamorphism at the Walker Mine Volcanogenic Sulfide Deposit Plumas County California written by Donald Charles Pietz and published by . This book was released on 1990 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annotated Bibliographies of Mineral Deposits in the Western Hemisphere written by John Drew Ridge and published by Geological Society of America. This book was released on 1972 with total page 706 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Index to Graduate Theses and Dissertations on California Geology 1990 Through 1997 written by and published by . This book was released on 1998 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Commencement Ceremony written by University of California, Davis. Graduate Division and published by . This book was released on 1991 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Masters Theses in the Pure and Applied Sciences written by W. H. Shafer and published by Plenum Publishing Corporation. This book was released on 1992 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses Listed by Discipline: Aerospace Engineering. Agricultural Economics, Sciences and Engineering. Architechtural Engineering and Urban Planning. Astronomy. Astrophysics. Ceramic Engineering. Communications Engineering and Computer Science. Cryogenic Engineering. Electrical Engineering. Engineering Mechanics. Engineering Physics. Engineering Science. Fuels, Combustion, and Air Pollution. General and Environmental Engineering. Geochemistry and Soil Science. Geological Sciences and Geophysical Engineering. Geology and Earth Science. Geophysics. Industrial Engineering. Marine and Ocean Engineering. Materials Science and Engineering. Mechanical Engineering and Bioengineering. Metallurgy. Meteorology and Atmospheric Science. 17 additional disciplines. Index.
Download or read book Geology and Mineralization of the Seaman Gulch Area East Shasta Mining District Shasta County California written by Douglas W. Prihar and published by . This book was released on 1987 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Seaman Gulch area is located approximately 20 miles east of Redding, California and is part of the eastern Klamath lithotectonic belt. Rock units of the area are chiefly mafic and silicic volcanics of island arc affinity and shale that are Permian to Triassic in age. Volcanic rocks of Tertiary and Quaternary age unconformably overlie the pre-Tertiary rocks. All pre-Tertiary rocks have been altered by hydro-thermal and(or) metamorphic processes. Stratabound epigenetic mineralization is hosted by metadacitic pyroclastics of the Bully Hill Rhyolite. The hypogene sulfide minerals present are pyrite, sphalerite, chalcopyrite, tetrahedrite-tennantite and galena. Minor amounts of supergene chalcocite are found. These sulfides occur as disseminations, stringer veinlets, massive pods and an irregular network around pyroclastic fragments. Controls that localized the occurrences of sulfides are intrusive rock-country rock contacts, permeability and porosity of pyroclastic rocks, faults, and fractures. The gangue mineralogy of the stringer veinlets consists of quartz, carbonate, and anhydrite. The distribution of sulfide minerals is zoned vertically and from bottom to top as follows: pyrite - chalcopyrite as disseminations and stringer veinlets; pyrite - sphalerite - chalcopyrite as disseminations, stringer veinlets, and networks; and pyrite - sphalerite - chalcopyrite - tetrahedrite-tennantite - galena as disseminations, stringer veinlets, and massive pods. Hydrothermal alteration assemblages are chloritic alteration, quartz - white mica alteration, propylitic alteration, silicification, argillic alteration, and carbonate alteration. These alteration assemblages display both vertical and lateral zonations. A central zone of chloritic alteration grades laterally into propylitic alteration, and upward into quartz-white mica alteration. The quartz - white mica alteration in turn grades laterally into propylitic alteration. Argillic alteration and carbonate alteration are genetically related but slightly later events that overprint the earlier assemblages. The mineralization in the Seaman Gulch area is similar to the stockwork zone that underlies Kuroko-type volcano-genic massive sulfide deposits. The sulfides and their associated products of hydrothermal alteration were deposited during submarine geothermal activity that was operative during the latest Permian time. The economic potential of the Seaman Gulch area is considered to be low because of the paucity of base metalbearing sulfides, their occurrence as chiefly disseminations and veinlets, and the restricted distribution of economic assays.
Download or read book Geological Setting of Volcanogenic Massive Sulphide Mineralization in the Kamiskotia Area written by B. Hathway and published by [Sudbury] : Ontario Geological Survey. This book was released on 2005 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Altered Volcanic Rocks written by Cathryn Gifkins and published by CODES-University of Tasmania. This book was released on 2005-01-01 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is about the processes and products of alteration in submarine volcanic successions. Its emphasis is on hydrothermal alteration associated with volcanic hosted massive sulfide deposits.
Download or read book Geology and Geochemistry of the Little Walker Volcanic Center Mono County California written by George R. Priest and published by . This book was released on 1979 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed mapping and geochemical analysis of Oligocene to early Pliocene volcanic rocks in the Little Walker volcanic center, Mono County, California have revealed a complex eruptive history. After eruption of widespread rhyolitic ash flows of the Valley Springs Formation in the Oligocene, Miocene to early Pliocene volcanism of the western Great Basin and northern Sierra Nevada was dominated by eruption of calc-alkalic, andesitic lavas bearing abundant hydrous mafic phenocrysts, and, thus, high H2O contents. These kinds of calc-alkaline magmas are associated with most of the major epithermal Au-Ag districts of the western Great Basin. A highly potassic latitic pulse of volcanism occurred at the Little Walker volcanic center about 9.5 m.y. ago during the ongoing calc-alkalic activity. The latitic series is unusually enriched in K and other incompatible elements, as well as Fe compared to the surrounding calc-alkaline rocks. The latites have mineralogic evidence of much lower H2O content than the calc-alkaline lavas; yet early latitic magmas were rich enough in volatiles to produce very large, welded ash-flow sheets (e.g., the Eureka Valley Tuff). Rapid evacuation of the magma reservoir beneath the Little Walker center during the ash-flow activity resulted in formation of the Little Walker caldera. Intracaldera volcanism culminated with extrusion of viscous, phenocryst-rich plug domes and coulees of transitionally calc-alkaline, low-K latite lava of the Lavas of Mahogany Ridge. The low-K latite series is severely depleted in all incompatible elements relative to early latitic rocks and has mineralogic, geologic, and trace element evidence of higher H2O content relative to early latites. Significant phenocrystic hornblende, association with hydrothermal alteration, and high Eu3 /Eu2 all suggest significant H2O concentration in the low-K latite magmas. These rocks probably come from a source region intermediate between that of the calc-alkaline and latite series. Trace and major element data favor generation of latitic magmas from a primitive mantle diapir. The diapir rose into a subduction zone that was actively generating widespread calc-alkalic lavas throughout the region from hydrous mantle and, possibly, lower crustal sources. The latite magmas were drier and hotter than the calc-alkaline magmas, but were also enriched in volatiles, particularly CO2, and incompatible elements from their undepleted mantle source. Rising latitic magmas may have gained additional incompatible elements by wall rock reaction and zone refining of upper mantle and lower crustal rocks. Extensive qualitative trace element evidence of crystal fractionation shows that incompatible elements may have been further concentrated by variable amounts of crystal settling. High-pressure (plagioclase-poor, pyroxene-rich) fractionation of the early, dry latitic series produced low-Ca-Mg latites with high Fe/Mg and A1203 but low Si02. Low-pressure (plagioclase rich) differentiation of the early latitic magmas produced quartz latite ash flows with high Si02 and moderate Fe/Mg, while low-pressure differentiation of hydrous low-K latite magmas yielded silicic low-K latite and quartz latite lavas with low Fe/Mg. More extensive separation of olivine relative to pyroxenes at low pressures and increased stability of subsilicic hydrous crystals and Fe-Ti oxides in the hydrous magmas account for changes in differentiation trends caused by Ptotal and PH2O variations. Lack of giant welded ash-flow sheets in the hydrous calc-alkaline series and common eruption of such ash flows from volcanic centers with rather anhydrous magmas led to the conclusion that H20/CO2 as well as total volatile content are critical controls on the likelihood of large scale, hot ash-flow eruptions. Giant, hot ash-flow sheets and associated calderas are favored in magmas with low H20/CO2 and high total volatile content. Basaltic and latitic volcanism in areas of thick sialic crust, where crystal fractionation is extensive are, therefore, the best sources of giant ash-flow sheets. H20/CO2 and total volatile content were also critical controls of the probability of hydrothermal ore deposition. Magmas with high H20/CO2 and moderate total volatile contents are most favored for ore deposition, because such magmas tend to form mesozonal or epizonal plutons rather than volcanic rocks. Plutonic crystallization of hydrous magma will yield a fluid phase capable of transferring incompatible metals and geothermal heat to ground water. If permeable structures and rocks are present, as in a caldera, widespread mineralization will be favored, but there may be no genetic relation between ore-forming magmas and magmas which produce calderas.
Download or read book Miscellaneous Paper Ontario Geological Survey written by Ontario Geological Survey and published by . This book was released on 1986 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydrothermal Fe Carbonate Alteration Associated with Volcanogenic Massive Sulfide VMS Deposits in Cycle IV of the Noranda Mining Camp Rouyn Noranda Quebec written by Ryan Wilson and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Massive sulfide deposits in the Noranda mining camp, northwestern Québec, are mainly associated with extensive footwall alteration defined by intense chloritization and sericitization. However, Fe-carbonate alteration also occurs in proximity to some deposits. To test the exploration significance of carbonate alteration in the camp, two areas of intense carbonate alteration were examined, around the small Delbridge deposit and near the new Pinkos occurrence in the Cyprus Rhyolite. Between 1969 and 1971, the Delbridge deposit produced 370,000 t of ore grading 9.6% Zn, 0.61% Cu, 110 g/t Ag, and 2.1 g/t Au. Recent drilling at the new Pinkos occurrence intersected 2.64 m of massive to semi-massive sulfides grading 8.1% Zn and 18.2 g/t Ag. Alteration mapping has shown that the distribution of Fe-carbonates can be used to identify vertically extensive zones of hydrothermal upflow at both properties. At Delbridge, intense Fe-carbonate alteration in brecciated rhyolite defines a pipe-like upflow zone that extends vertically for up to 300 m within the stratigraphic footwall of the massive sulfides and 100 m into the hanging wall. The location of known massive sulfide mineralization coincides with the intersection of the alteration pipe and a favorable horizon marked by the occurrence of fine-grained volcaniclastic rocks. At Pinkos, a similar zone of Fe-carbonate alteration occurs in outcrops of coherent rhyolite. Fe-carbonate alteration is most intensely developed along polygonal cooling fractures in massive rhyolite and decreases in intensity towards the centers of the columns. Fe-carbonate stringers and locally abundant matrix carbonate occur in fragmental rocks at the stratigraphic top of the coherent rhyolite flows and are most intense at the location of sulfide-bearing outcrops that mark the known mineralized horizon. Whereas Fe-carbonate alteration defines the central part of the hydrothermal upflow zones at both properties, disseminated pyrite occurs at the margins and is widespread outside the main upflow zones. This may indicate that Fe-carbonate in the main upflow zones formed at the expense of earlier disseminated sulfides. Replacement of pyrite by synvolcanic Fe-carbonate alteration at Delbridge and Pinkos can probably be attributed to a relatively high concentration of dissolved CO2, possibly of magmatic origin, in the main-stage ore-forming fluids.
Download or read book Volcanic Stratigraphy and Epithermal Mineralization of the DeLamar Silver Mine Owyhee County Idaho written by Robert Edward Thomason and published by . This book was released on 1983 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The DeLamar Silver Mine is in the north-trending Owyhee Mountains of southwest Idaho. As part of the Silver City region it is included in the Basin and Range physiographic province. The lithologic units of the Silver City region, surrounding the DeLamar Silver Mine, are composed mostly of Cretaceous granitic rocks and Miocene volcanic rocks. The volcanic rocks which vary in composition from basalt to rhyolite are predominant in aerial extent. Regional structure is dominated by a set of N10-20°W trending oblique-slip, high angle faults and a less pronounced set trending N75°W. These faults may be related to crustal extension in the Basin and Range province and to rifting in the Snake River Plain. The mineral deposits of the Silver City region occur mostly as epithermal vein fillings of fractures and faults. The predominant trend of the veins is north-northwest. The DeLamar Silver Mine is in a complex Miocene volcanic sequence. Units of various compositions including basalt, latite, rhyolite, and andesite were emplaced as coalescing flows, exogeneous domes, and necks. A porphyritic rhyolite is the most widespread unit in the mine area. Epithermal silver and gold mineralization at DeLamar is most commonly concentrated in the well-fractured, silicified, upper part of the porphyritic rhyolite. The most continuous mineralization is below the clay-altered base of an overlying fine-grained banded rhyolite. Mineralogy of the deposit is dominated by sulfides and selenides. Naumannite is the dominant silver mineral commonly occurring as small disseminated grains in quartz. Other silver bearing minerals include; acanthite, argentopyrite, and pyrargyrite. Fine-grained free gold is highly disseminated in the gangue. Pyrite is the most dominant and widespread sulfide of the deposit followed in abundance by marcasite. The gangue consists almost entirely of quartz. Several varieties occur including lamellar quartz; white, gray, and black common vein quartz; and well formed crystalline quartz. Hydrothermal alteration minerals at DeLamar include sericite, secondary quartz, kaolinite, alunite, chlorite, and zeolites. Mineralogy of the veins and alteration at DeLamar suggests that hydrothermal solutions were probably at temperatures 100 to 300°C. These solutions are believed to have been highly diluted sodium-chloride waters closely related to the rhyolitic volcanism.
Download or read book Volcanic associated Massive Sulfide Deposits Processes and Examples in Modern and Ancient Settings written by C.T. Barrie and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physical Volcanology and Hydrothermal Alteration of the Footwall Rocks to the Archean Mattabi Massive Sulfide Deposit Northwestern Ontario written by Jamieson Scott Walker and published by . This book was released on 1993 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mesothermal hypothermal i e Hydrothermal Mineralization and Genetically Related Wall Rock Alternation in the Bismark District Madison County Montana written by John Hugh Ravenscroft and published by . This book was released on 1985 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Radiometric Ages of Volcanic and Plutonic Rocks and Hydrothermal Alteration mineralization in the Tonopah Mining District and Vicinity Nye and Esmeralda Counties Nevada written by Miles L. Silberman and published by . This book was released on 1978 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:
