Date of Award
Master of Science
Geological and Environmental Sciences
Dr. Ronald B. Chase
Dr. Christopher J. Schmidt
Dr. W. Thomas Straw
Masters Thesis-Open Access
Peltitic schist, quartzofeldspathic gneiss, and calc-silicate rocks of the Precambrian Belt Supergroup hav ebeen intruded by granatic plutons of the northeastern Idaho batholith within the vicinity of the southern Bitterroot Range, Montana. These units were mylonitized along the eastern margin of the intrusive complex, with shear surfaces presently dipping approximately 20° to the east. Rhyolitic ash flows and associated mafic to felsic dikes developed on and within the granitic-metamorphic terrance during Tertiary time. Numerous northeast- trending and northwest-trending faults and joints are present throughout the mapped region.
The following events play a major role in the geologic history: 1) amphibolite- grade metamorphism, 2) emplacement of granitic plutons, 3) mylonitization resulting from crustal adjustments or forceful magmatic intrusion, and 4) volcanism associated with faulting, perhaps, as part of a caldera system.
Reichert, Randall, "The Geology of Burnt Ridge Quadrangle and Vicinity Ravalli County, Montana" (1983). Masters Theses. 1617.