The role of Precambrian rock compositions and fabrics on the structural development of a large foreland fold, southern Front Range, Colorado
- Western Michigan Univ., Kalamazoo, MI (United States). Dept. of Geology
Royal Gorge arch is a south-plunging, eastward asymmetrical, broad foreland fold. Precambrian lithologies occupy more than 50 km[sup 2] of the fold core and vary considerably from amphibolite-grade quartzofeldspathic, migmatitic gneiss on the south to poorly foliated to massive granodioritic gneiss on the north. The boundary between these two lithologies is marked by abundant and fairly concordant granitic pegmatites, and a change in fold style from broad folding in the northern sector to tighter folding to the south. Cover rocks are broadly arched carbonates, arenites, and lutites ranging in age from Ordovician to Late Cretaceous. Based on foliation patterns, basement rocks can be divided into seven homogeneous, cylindrical domains. Jointing appears strongly controlled by the foliation patterns. Joints and foliations in each domain show rotation in the same direction and magnitude with respect to other domains. The pattern of jointing in three sedimentary domains changes from flank to flank and does not match jointing in the Precambrian core, except in the unfoliated sectors. The sedimentary domains do not show the same sense of rotation as basement domains and basement joint clusters. These differences in deformation of the sedimentary cover reflect heterogeneous folding in response to fabric differences in the adjacent basement rocks. Analysis of slickenlines indicates that a non-uniform stress field developed within the Precambrian basement. Stresses apparently refracted through the core of the uplift, with refraction directions traceable across domain boundaries.
- OSTI ID:
- 6974889
- Report Number(s):
- CONF-9404217--
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Journal Name: Geological Society of America, Abstracts with Programs; (United States) Vol. 26:5; ISSN GAAPBC; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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