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Bruce Bryant

Publications and source records attributed to Bruce Bryant.

At least 37 records · Page 2Linked to original sources
USGS1999

Laramide to Holocene structural development of the northern Colorado Front Range

The Rocky Mountain province of the United States is a classic basement-involved foreland orogen. Deformation during the Late Cretaceous to Eocene Laramide orogeny created an anastomosing system of basement-cored arches that bound the northern and eastern margins of the Colorado Plateau and the elliptical sedimentary basins of the Rockies. The tectonic mechanism for Laramide deformation remains controversial, with proposed mechanisms ranging from subcrustal shear during low-angle subduction (Bird, 1988, 1998; Hamilton, 1988) to detachment of the upper crust during plate collision to the west (Oldow and others, 1990; Erslev, 1993). The Rocky Mountains south of Wyoming have the additional complication of a period of mid-Tertiary igneous activity and sedimentation that coincides with Neogene extension along the Rio Grande rift. This field trip (Fig. 1) will explore the Laramide to Holocene structural development of the southern Rocky Mountains by examining the geologic record exposed in the northern Front Range of Colorado. The Front Range starts north of Canon City, Colorado, and trends north-northwest to Golden, Colorado. North of Golden, the range takes a more northerly trend toward the Wyoming border where it bifurcates into the north-trending Laramie Range (Brewer and others, 1982) and the north-northwest-trending Medicine Bow Range.

Colorado↗
USGS1978

Granite of Rosalie Peak, a phase of the 1700-million-year-old Mount Evans Pluton, Front Range, Colorado

The Rosalie Granite was a name applied by S. H. Ball in 1906 to a granite which forms a ridge between Mount Evans and Mount Rosalie (renamed Rosalie Peak). The type locality originally designated for the Rosalie Granite was in a pluton (later called the Rosalie lobe) 10 kilometers southeast of Rosalie Peak on Deer and Elk Creeks. The name "Rosalie Granite" was abandoned by T. S. Levering in 1929 because the granite of the Rosalie lobe is actually the distinctly younger Pikes Peak Granite, only 1,030 m.y. (million years) old, whereas the "Rosalie Granite" between Mount Evans and Rosalie Peak is a felsic phase of the l,700-m.y.-old Mount Evans pluton. In addition, the Rosalie Granite has more MgO and Sr and less Na 2 O, F, and Rb than the Pikes Peak Granite, and the two granites differ petrographically. In order to avoid confusion in correlation, the name Rosalie should not be applied to rocks in this area. Therefore, we propose that the Rosalie lobe be renamed Lone Rock pluton and that the "Rosalie Granite" be informally referred to as the granite of Rosalie Peak until it can be attached to a formal geologic rock unit.

Colorado↗
USGS1975

Relations between thermal, photographic, and topographic linears and mapped and measured structures in a Precambrian terrane in Colorado

Comparison of orientation of faults, foliations, and joints, observed during geologic mapping in Colorado, with thermal, photographic, and topographic linears shows that topographic linears are statistically useful indicators of mappable faults and fractures, photographic linears are less useful, and thermal linears, believed to represent zones of moisture concentration, are parallel to faults, foliations, and, a statistically minor, but more open joint set.

Colorado↗