Phase chemistry of the layered series, Raggedy Mountain Gabbro Group, Oklahoma

dc.contributor.advisorPowell, Benjamin N.en_US
dc.creatorPhelps, David Williamen_US
dc.date.accessioned2018-12-18T21:16:11Zen_US
dc.date.available2018-12-18T21:16:11Zen_US
dc.date.issued1976en_US
dc.description.abstractGabbroic igneous rocks of lower Cambrian age outcrop in southwestern Oklahoma in the Wichita Mountains and are here referred to as the Raggedy Mountain Gabbro Group. The Raggedy Mountain Gabbro Group consists of small gabbroic to dioritic sills and dikes and a large layered intrusion (4 km by 8 km in the subsurface) referred to as the layered series. The layered series has only approximately 2 m of section exposed at the surface which has been divided into three units (K, L, and M zones) on the basis of lithology. Approximately 1 samples were collected from different stratigraphic elevations from three locations in the layered series. All handsamples were thinsectioned, examined optically and selected samples chosen for microprobe analysis. Petrographically the rocks of the layered series are adcumulates. Plagioclase is a cumulus phase and the most abundant mineral in all thin sections. Clinopyroxene occurs in large oikocrysts with two distinct textures distinguished by the size of plagioclase chadacrysts. Olivine is cumulus; most grains are surrounded by symplectic coronas of orthopyroxene and magnetite. Orthopyroxene also occurs as an intercumulus phase. Microprobe analyses were performed on olivine, clinopyroxene, orthopyroxene and plagioclase. Oscillatory zoning observed in some plagioclase crystals is tentatively attributed to circulation of the crystals by convection currents. Highly calcic partial rims on plagioclase crystals may be a result of increasing PH during crystallization of trapped pore liquid. There is evidence that the symplectic reaction rims around olivine crystals are a result of increasing oxygen fugacity in the crystallizing trapped pore liquid. The intercumulus orthopyroxene crystallizing from pore liquid in communication with overlying magma, the low Al2O3 and TiO2 values in clinopyroxenes, and the presence of low calcium pyroxene lamellae in clinopyroxene indicate crystallization from a tholeiitic series. Compositions of clinopyroxenes vary from Fs. Cumulus clinopyroxenes symplectic coronas range from Fs magma. Increase in iron in the cumulus ferromagnesian minerals and the increase in sodium in the plagioclase upwards in the section suggests that crystal settling out of a differentiating basaltic magma is responsible for the formation of the layered series. The present level of exposure may be approximately midway between the top and bottom of the intrusion.en_US
dc.format.digitalOriginreformatted digitalen_US
dc.format.extent166 ppen_US
dc.identifier.callnoThesis Geol. 1976 Phelpsen_US
dc.identifier.citationPhelps, David William. "Phase chemistry of the layered series, Raggedy Mountain Gabbro Group, Oklahoma." (1976) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/104010">https://hdl.handle.net/1911/104010</a>.en_US
dc.identifier.digitalRICE1636en_US
dc.identifier.urihttps://hdl.handle.net/1911/104010en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.titlePhase chemistry of the layered series, Raggedy Mountain Gabbro Group, Oklahomaen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentEarth Scienceen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Artsen_US
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