Petrology and structure of precambrian crystalline and tertiary igneous rocks, Manhattan District, Larimer County, Colorado
The Manhattan district is located in the northwest quarter of the Rustic quadrangle about 30 miles northwest of Fort Collins, Colorado, and includes approximately five square miles of primarily Precambrian terrane. Biotite gneiss, hornblende gneiss, and amphibolite, the oldest rocks in the area, have been metamorphosed to the sillimanite-almandine-orthoclase subfacies of the amphibolite facies. The metamorphic rocks have been intruded by Log Cabin granite which comprises the majority of the rock in the area. Granite shows evidence of forceful, but not very disruptive, intrusion. Inhomogeneity ...
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