Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Physical Sciences and Mathematics
The Precambrian Volcanic Stratigraphy And Petrology Of The Des Arc Ne 7 1/2 Minute Quadrangle, South Central St. Francois Mountains, Missouri, Vernon Max Brown
The Precambrian Volcanic Stratigraphy And Petrology Of The Des Arc Ne 7 1/2 Minute Quadrangle, South Central St. Francois Mountains, Missouri, Vernon Max Brown
Doctoral Dissertations
"The Precambrian volcanics in the Des Arc NE 7½ minute quadrangle are composed predominantly of rhyolitic ash-flow tuffs with minor rhyolitic, trachytic, and andesitic lavas, and basaltic dikes. Thirty-seven volcanic units were identified, mapped, and informally named. A minimum of 1,000 meters of volcanic section is present. The rhyolites consist of phenocrysts of albitized alkali feldspar, albitic plagioclase, quartz, opaques, and ferromagnesium relicts set in a devitrified and locally recrystallized felsitic matrix. Pumice and lithophysal structures are common in the ash flows.
Chemically, the rhyolites are quite similar. The potassium to sodium ratio in individual units, however, tends to vary …
Comparative Petrographic, Petrochemical And Spectrographic Analyses Of The Precambrian Granitic Rocks Of Southeastern Missouri, Eva B. Kisvarsanyi
Comparative Petrographic, Petrochemical And Spectrographic Analyses Of The Precambrian Granitic Rocks Of Southeastern Missouri, Eva B. Kisvarsanyi
Masters Theses
"Petrographic, petrochemical and spectrographic studies were completed on selected Precambrian granitic rock samples from Southeastern Missouri. This investigation contributes to a more detailed knowledge of the Precambrian granitic rocks of this part of the state.
Petrographic analysis of forty-four thin sections of granitic rocks from the St. Francois Mountains area revealed six different granite types. These have been named the Fredericktown, Knoblick, Doerun, Graniteville, Klondike and Silvermine granites. These rocks form a large part of a composite batholith. More than one period of granitic intrusion is represented, but differentiation also contributed to the formation of this diversity of the rocks. …