Three tectonic provinces within the Cordilleran System, are analyzed in terms of tectonic framework. (1) Precambrian terrain of North-Central Colorado; (2) The Pacific Northwest; and (3) The San Andreas-Garlock fault system and associated features. In each case a close relationship is seen to exist between: (1) Arcuate mountain development; (2) Precambrian basement fabric; (3) Major fault patterns; and Major mineral occurrences. The arcuate trends developed when the basement was still mobile. Later competent deformation rejuvenated pre-existing lines of weakness.
Tectonic Analysis of the Precambrian Terrain of North-Central Colorado
The Precambrian terrain of North-Central Colorado is dominated by several north-eastward directed convex mountain arcs. The present discussion will concentrate on the arc whose axial trace trends northeastward from the northern Sawatch range through the Gore and Williams ranges. This axial trend continues on through the batholith south of Granby reservoir, and meets the Great Plains near Fort Collins, Colorado. The arcuate nature of this trend is outlined by the courses of the Eagle, Arkansas, Blue, Fraser, Arapahoe, Buckhorn and Cache la Poudre. (South Fork) rivers.
The following discussion will indicate that there is an intimate relationship between the major fault patterns of North Central Colorado and the overall arcuate framework.
The smooth arcuate