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Rock alteration and vein mineralization at the Buffalo Mine, Grant County, Oregon /Pilcher, Stephen Hathaway. January 1959 (has links)
Thesis (M.S.)--Oregon State College, 1959. / Typescript. Includes bibliographical references (leaves 80-83). Also available on the World Wide Web.
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The structure and metamorphism of the Pewsey Vale area North - East of Williamstown, S.A.Offler, Robin January 1966 (has links)
The structure and petrology of Upper Precambrian and Cambrian rocks have been studied in detail, in an area 38 miles north - east of Adelaide, South Australia. The rocks occur within a broad zone of high grade metamorphism on the eastern side of the Mt. Lofty Ranges. The Upper Precambrian succession consists predominantly of pelitic and semi - pelitic schists, quartzites, calc - silicate rocks and calc - schists, and the Cambrian sequence of quartzo - feldspathic schists, migmatites, granite gneiss, calc - silicate rocks and minor pelitic schists and quartzites. The rocks have reached the sillimanite grade of metamorphism and the metamorphism is of the low pressure - intermediate type. Dolerites, pegmatites, minor granodiorites and granites intrude the meta - sediments. Mineralogical and structural relationships of the granite gneiss, indicate that it has been formed by recrystalliaation of the quartzo - feldspathic schists. Small scale metamorphic differentiation, appears to have accompanied the recrystallization. The migmatites are believed to have been formed by metamorphic differentiation rather than by anatexis. Three phases of deformation are recognised in the Upper Precambrian rocks and two in the Cambrian. The second deformation recorded in the Upper Precambrian rocks does not appear in the Cambrian rocks. Each deformation has been accompanied by the formation of foliation. In the Proterozoic rocks deformed by the second and third phases of folding, the foliation is a crenulation cleavage. The deformations in both the Upper Proterozoic and Cambrian sequences are considered to be related. Petrofabric studies of quartz, scapolite and biotite are related to the respective macroscopic structures. An analysis of the chronology of crystallisation and deformation of these rocks indicates that crystallisation continued during and after each phase of deformation. Faulting commenced either prior to or during meta - morphism. Intense metasomatic activity followed a later phase of faulting resulting in the widespread development of albitites and in some cases talc ore bodies. The albitites formed in the fault zone were subsequently brecciated by further movement and later healed by the introduction of more metasoinatic fluid. / Thesis (Ph.D.) -- University of Adelaide, Department of Geology, 1966.
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The petrology of the Kerimasi carbonatite volcano and the carbonatites of Oldoinyo Lengai with a review of other occurrences of extrusive carbonatitesChurch, Abigail Ann January 1996 (has links)
Extrusive carbonatites are rare igneous rocks with just 37 known localities. The majority are calciocarbonatites, the principal exception being those of the active volcano, Oldoinyo Lengai, which are strongly alkaline. Unresolved questions concerning extrusive carbonatites include: 1. Why are extrusive carbonatites at Lengai chemically different from all others? 2. Could the extrusive calciocarbonatites originally have had alkaline compositions? In order to address these questions extrusive carbonatites from both Lengai and the adjacent volcano, Kerimasi, were collected and compared. A compilation of all the available data on known extrusive carbonatites is also presented. The major results documented in this thesis are: 1. Alkali carbonatites from Oldoinyo Lengai erupted in 1993 contain petrographic evidence for an origin by liquid immiscibility from a highly fractionated peralkaline silicate melt (wollastonite nephelinite). 2. The suite of silicate rocks at Kerimasi are derived from a primary olivine nephelinite by fractional crystallisation and cumulus processes. 3. Extrusive carbonatites at Kerimasi are not genetically related to the silicate suite. By contrast intrusive sovites also present, originated by liquid immiscibility from a primitive silicate magma, equivalent to a melilite, nephelinite, at low pressure. 4. Extrusive calciocarbonatites from Kerimasi were erupted directly from the mantle. They contain phenocrysts (previously interpreted as pseudomorphs after alkali carbonate) which are now thought to have been dolomite containing calcite exsolution lamellae. 5. Of the 35 other extrusive carbonatite occurrences, none show any petrographic or geochemical evidence of having originally being alkaline. Therefore extrusive carbonatites from Oldoinyo Lengai are thought to be unique. 6. Of the 37 extrusive carbonatites, 50% are associated with melilitites or melilitebearing rocks, 27% are associated with nephelinites and the remaining 23% were erupted with no associated silicate magmas.
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The structure and metamorphism of the Pewsey Vale area North - East of Williamstown, S.A.Offler, Robin January 1966 (has links)
The structure and petrology of Upper Precambrian and Cambrian rocks have been studied in detail, in an area 38 miles north - east of Adelaide, South Australia. The rocks occur within a broad zone of high grade metamorphism on the eastern side of the Mt. Lofty Ranges. The Upper Precambrian succession consists predominantly of pelitic and semi - pelitic schists, quartzites, calc - silicate rocks and calc - schists, and the Cambrian sequence of quartzo - feldspathic schists, migmatites, granite gneiss, calc - silicate rocks and minor pelitic schists and quartzites. The rocks have reached the sillimanite grade of metamorphism and the metamorphism is of the low pressure - intermediate type. Dolerites, pegmatites, minor granodiorites and granites intrude the meta - sediments. Mineralogical and structural relationships of the granite gneiss, indicate that it has been formed by recrystalliaation of the quartzo - feldspathic schists. Small scale metamorphic differentiation, appears to have accompanied the recrystallization. The migmatites are believed to have been formed by metamorphic differentiation rather than by anatexis. Three phases of deformation are recognised in the Upper Precambrian rocks and two in the Cambrian. The second deformation recorded in the Upper Precambrian rocks does not appear in the Cambrian rocks. Each deformation has been accompanied by the formation of foliation. In the Proterozoic rocks deformed by the second and third phases of folding, the foliation is a crenulation cleavage. The deformations in both the Upper Proterozoic and Cambrian sequences are considered to be related. Petrofabric studies of quartz, scapolite and biotite are related to the respective macroscopic structures. An analysis of the chronology of crystallisation and deformation of these rocks indicates that crystallisation continued during and after each phase of deformation. Faulting commenced either prior to or during meta - morphism. Intense metasomatic activity followed a later phase of faulting resulting in the widespread development of albitites and in some cases talc ore bodies. The albitites formed in the fault zone were subsequently brecciated by further movement and later healed by the introduction of more metasoinatic fluid. / Thesis (Ph.D.) -- University of Adelaide, Department of Geology, 1966.
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Geologic history and petrogenesis of alkaline volcanic rocks, Mt. Morning, Antarctica.Muncy, Harold Lee. January 1979 (has links)
Thesis (M.S.)--Ohio State University. / Bibliography: leaves 104-112. Available online via OhioLINK's ETD Center
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Petrographic image analysis as a tool to quantify porosity and cement distribution /Nejedlik, John. January 2001 (has links) (PDF)
Thesis (M.Sc.)--University of Adelaide, National Centre for Petroleum Geology & Geophysics, 2002. / Includes bibliographical references (leaves 153-157).
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Petrologie a genetické vztahy alkalických intruzivních hornin roztockého intruzivního komplexu / Petrology and genetic relationships of alkaline intrusive rocks of the Roztoky Intrusive ComplexMysliveček, Jakub January 2019 (has links)
Roztoky Intrusive Center (33-28 Ma) is connected with tertiary volcanic activity in the territory of the Bohemian Massif (Czech Republic). It is located in the České středohoří volcanic complex on the tectonic line of the Ohře rift. The aim of this work was to petrologically describe local rocks and to verify the possible connection of the Roztoky Intrusive Center (RIC) with carbonatite magmatism, as could be suggested by the presence of alkaline rocks including their exotic types (essexites, monzodiorites, sodalitic syenites,…). It is assumed that there is a hidden carbonatite intrusion under the RIC caldera structure, which may also indicate geophysical manifestations of two hidden gravimetric minimas. In a detailed exploration of a drill core from the R-2 borehole from the 1960s, a petrographic rocks composition of a part of the caldera filling was described, including new find of xenolite of carbonatite in 286,5 m of R-2 borehole. By means of geochemical and micro-probe analyzes the well material including carbonatite was examined in detail. Carbonate mineralization with high REE contents was found in carbonatite, but also in the exocontact of the previously described silicocarbonatite (Rapprich et al. 2017). The discovery of carbonatite xenolite and the presence of minerals with high concentrations of...
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