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51	Mineral-Scale Sr Isotopic Study of Plagioclase in the Mafic Dikes of the North American Wall and the Diorite of the Rockslides, Yosemite Valley, California. Nelson, Wendy Rae 16 March 2006 (has links) (PDF) The North American Wall mafic dikes and the diorite of the Rockslides mafic complex in the intrusive suite of Yosemite Valley show evidence of mixing with their host granites as well as with earlier components. Whole rock major element variation diagrams indicate the mafic rocks mixed with a more silicic component, but extrapolating to the silica end member does not yield the same result with each element. Trace element concentrations show a wide variation in concentration of Cr and Ni, with two samples showing enrichment in Cr (>300 ppm) and Ni (~44 ppm) compared to other samples (Cr =13-94 ppm; Ni = 5-26 ppm). These samples have the most primitive epsilon Nd values (-3.3, -3.5 at 100 Ma) analyzed thus far for the intrusive suite, indicating the suite has a larger range of isotopic values than previously thought. Delta 18 oxygen for Rockslides samples vary from 6.6 to 7.5 per mille (6 samples, average 7.03), higher than the 5.5 + 0.3 range for the mantle, indicating the presence of a crustal component in the system. Plagioclase phenocrysts within each unit display bimodal compositional populations. Subhedral to euhedral partially resorbed calcic cores (mode = An84-88) are reminiscent of a mafic magma, while sodic rims (mode = An48-50) are the product of a more silicic component. Very little to no intermediate zoning is present between cores and rims. Mineral-scale 87Sr/86Sr analysis of plagioclase cores and rims are consistent with previously published enriched bulk-rock ratios for the suite (0.7065-0.7078), but are unable to distinguish between mixing components. The plagioclase isotopic data show no direct evidence for a depleted mantle melt component contaminated by crustal assimilation. However, the mafic rocks are comparable to high-alumina basalts, whose generation involves crystal fractionation and magma mixing/crustal assimilation. The evolution of these high-alumina basalts provides an opportunity for magma contamination to take place before plagioclase crystallization, thus explaining why plagioclase core-rim analysis could not distinguish between mixing components. Therefore, it is possible but not necessary to derive the rocks from an enriched mantle source, especially since the bulk-rock oxygen isotopic values indicate a significant crustal component is present. anorthite contamination high-alumina basalt isotope magma mixing mantle micro-sample Nd oxygen isotopes plagioclase pluton Sierra Nevada batholith Sr trace elements Yosemite Valley Geology
52	Petrologic Significance of Multiple Magmas in the Quottoon Igneous Complex, NW British Columbia and SE Alaska Thomas, Jay Bradley Jr. 26 June 1998 (has links) The quartz dioritic Quottoon Igneous Complex (QIC) is a major Paleogene (65-56 Ma) magmatic body in NW British Columbia and SE Alaska that was emplaced along the Coast shear zone (CSZ). The QIC contains two different igneous suites that provide information about source regions, magmatic processes and evolving tectonic regimes that changed from a dominantly convergent to a dominantly strike-slip regime between 65 to 55 Ma. Heterogeneous suite I rocks (e. g. along Steamer Passage) have a pervasive solid-state fabric, abundant mafic enclaves and dikes, metasedimentary screens, and variable color indices (25-50). The homogeneous suite II rocks (e. g. along Quottoon Inlet) have a weak (to absent) fabric developed in the magmatic state (aligned feldspars, melt filled shears), and more uniform color indices (24-34) than in suite I. Suite I rocks have Sr concentrations <750 ppm, avg. LaN/YbN = 10.4, and initial 87Sr/86Sr ratios that range from 0.70513 to 0.70717. The suite II rocks have Sr concentrations >750 ppm, avg. LaN/YbN = 23.1, and initial 87Sr/86Sr ratios that range from 0.70617 to 0.70686. This study proposes that the parental QIC magma (initial 87Sr/86Sr = 0.706) can be derived bypartial melting of an amphibolitic source reservoir at lower crustal conditions. Geochemical data (Rb, Sr, Ba and LaN/YbN) and initial 87Sr/86Sr ratios preclude linkages between the two suites by fractional crystallization or assimilation and fractional crystallization (AFC) processes. The suite I rocks are interpreted to be the result of magma mixing between the QIC parental magma and a mantle derived magma. The samples do not lie along a single mixing line due to continued evolution through fractional crystallization/AFC processes subsequent to magma mixing. The suite II rocks may be generated by AFC. Initial 87Sr/86Sr ratio data suggests that similar processes to those that affected the QIC may also have operated during the generation of other portions of the Great Tonalite Sill of southeast Alaska. / Master of Science Quottoon pluton quartz diorite tonalite magma British Columbia Alaska petrography major elements trace elements rare earth elements geochemistry Sr isotopes geochemical modeling Great Tonalite Sill
53	Nuclear reactor core model for the advancednuclear fuel cycle simulator FANCSEE. Advanceduse of Monte Carlo methods in nuclear reactorcalculations Skwarcan-Bidakowski, Alexander January 2017 (has links) A detailed reactor core modeling of the LOVIISA-2 PWR and FORSMARK-3BWR was performed in the Serpent 2 Continuous Energy Monte-Carlocode.Both models of the reactors were completed but the approximations ofthe atomic densities of nuclides present in the core differedsignificantly.In the LOVIISA-2 PWR, the predicted atomic density for the nuclidesapproximated by Chebyshev Rational Approximation method (CRAM)coincided with the corrected atomic density simulated by the Serpent2 program. In the case of FORSMARK-3 BWR, the atomic density fromCRAM poorly approximated the data returned by the simulation inSerpent 2. Due to boiling of the moderator in the core of FORSMARK-3,the model seemed to encounter problems of fission density, whichyielded unusable results.The results based on the models of the reactor cores are significantto the FANCSEE Nuclear fuel cycle simulator, which will be used as adataset for the nuclear fuel cycle burnup in the reactors. / FANCSEE Nuclear Reactor Physics simulation FANCSEE Serpent energy neutron cross section Bateman atom isotope fission reaction uranium plutonium capture physics power calculation burnup Kärnkraft Reaktor Kärna Simulering FANCSEE uran pluton Serpent energi atom isotop fisson Bateman Energy Systems Energisystem

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