Geological Sciences Theses and Dissertations
Permanent URI for this collection
Browse
Browsing Geological Sciences Theses and Dissertations by Content Type "Thesis / Dissertation"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item Open Access CALCULATION OF EMPIRICAL CORRELATION COEFFICIENTS IN MULTI-COMPONENT OXIDE SYSTEMS FOR THE REDUCTION OF ELECTRON MICROPROBE DATA(University of Oregon, 1977-09) Dalheim, Peggy AnnThe purpose of this project was twofold - to synthesize several electron microprobe glass standards in the system: SiO2 - Al 2O 3 -- Cao -- MgO, and to utilize these standards in empirically calculating a set of binary correlation coefficients for use in the Bence-Albee data reduction method. Ten standards were prepared using the four end member oxides in coarse, crystalline form as starting materials (99.9+% purity). The careful synthesis and extensive analysis of the standards insured that they are homogeneous with compositions known to better than 5xl0- 4 oxide weight percent. The X-ray intensities measured for Si, Al, Ca and Mg in the standards and the oxides, plus the known compositions of the glasses provided the information necessary to empirically derive the set of binary correlation coefficients ("alpha factors") within the SiO2 - Al2O3 - CaO - MgO system.Item Open Access Geology of Mt. McLoughlin(University of Oregon, 1974-06) Maynard, Leroy CarsonThe purpose of this investigation is to contribute information about High Cascade volcanoes by studying one of them, Mt. McLoughlin, in detail. The study provides data on 1) the distribution and abundance of rock types, 2) the geologic history of the area, 3) the structural and contact relation of the High Cascades to the Western Cascades, and 4) the variation and evolution of rock types.Item Open Access The History and Petrography of the Basalts of Oregon(University of Oregon, 1931-06) Fisk, Harold N.Item Open Access Petrography and Petrology of Some Intrusive Bodies in the Southern Willamette Valley, Oregon.(University of Oregon, 1964) Holmes, John ShawMany post-middle Oligocene bodies of intrusive rocks are located in the southern Willamette Valley near Eugene, Oregon. Six of these which fora topographic highs, Creswell Butte, Spencer Butte, East Butte, Skinner Butte, Gillespie Butte, and North Butte, are examined in detail. From outcrop patterns, aerial photos, available literature, and field observations, the author believes the buttes to be sills or sill-like structures, concordant or slightly discordant with the surrounding Eugene Formation. Specifically, Creswell Butte,. Spencer Butte, and East Butte are eastward dipping sills; Skinner Butte is a sill-like structure dipping northwest; Gillespie Butte is a phacolith occupying a local synclinal fold plunging to the northwest, North Butte 1s a small laccolith with a feeder dike below the outcrop. All six buttes have similar lithological characteristics. They are medium- to fine-grained basalts with an ophitic and in places glomeroporphyritic texture. Plagioclase (labradorite) 1s the predominant mineral and coexists with lesser amounts o! the pyroxenes, hypersthene and ferroaugite. Some samples have trachytic texture. Hypersthene and ferroaugite are present at Creswell, Spencer, Gillespie, and North Buttes, but only the monoclinic pyroxene is present at East and Skinner Buttes. The ferromagnesium grains are moderately altered to chlorophaeite. This chloritic material appears to have altered from hypersthene mainly, but in some samples it has replaced ferroaugite. Other minerals, in minor quantities, are magnetite, ilmenite, apatite, and zircon. There is no evidence supporting differentiation within the buttes. The constant Fe2/Mg2 ratio suggests the same magma source tor all six buttes and thus rules out the possibility of extensive differentiation. There is, however, variation in the pyroxene content, which suggest a temperature variation during intrusion. The two-pyroxene basalts in the thesis area represent higher temperature conditions where the hypersthene was 'frozen' in the rocks and not allowed to undergo a normal inversion to pigeonite. The basalts which contain only ferroaugite indicate a temperature of formation lower than that normal for a two-pyroxene basalt.