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The Renova "Syenite" Porphyry Madison County, Montana, James H. Clement
The Renova "Syenite" Porphyry Madison County, Montana, James H. Clement
Bachelors Theses and Reports, 1928 - 1970
Unique feldspar porphyries, syenitic in appearance, and granitic in composition, form an unusually thick sill intruding pre-Cambrian Belt graywacke about eight miles south of Whitehall in southwestern Montana. Commercial deposits of gold and silver ores occur nearby, and may possibly be genetically related to the porphyry, although direct association is not evident. The geologic age is believed to be late Cretaceous or early Tertiary, and the sill may be related to the Tobacco Root batholith.
Structure Of Southwestern Montana, Donald W. Levandowski
Structure Of Southwestern Montana, Donald W. Levandowski
Bachelors Theses and Reports, 1928 - 1970
Intrusions of granitic rocks on a large scale are commonly found in the central part of folded mountain systems. Igneous rocks, intrusive and extrusive, are widespread in the mountains of southwestern Montana. An examination of the structural pattern of this area indicates that the fold trends form a radial pattern. How and why this pattern formed and its relation to the igneous activity in the area have not yet been discussed in the literature.
Basic Sills In Cottonwoood Creek Canyon, Jefferson County, Montana, Dale F. Kittel
Basic Sills In Cottonwoood Creek Canyon, Jefferson County, Montana, Dale F. Kittel
Bachelors Theses and Reports, 1928 - 1970
A stratigraphic section of about 2600 feet of upper Beltian to lower Devonian formations exposed in Cottonwood Creek Canyon 11 miles east of Whitehall, Montana, contains about 20 igneous sills. These sills are from 5 to 20 feet thick, and grade from granogabbro to quartz basalt, except for one sill which is 165 feet thick, and is composed of granogabbro and red syenite. The whole sedimentary series is isoclinally folded, and the sills follow the bedding planes closely with localized crosscutting through the beds.