Syndepositional deformation, sedimentation, and regional tectonics of an Ancestral Rocky Mountain basin, central Colorado trough, Colorado
Abstract
Sedimentological and structural data from Pennsylvanian-Permian synorogenic deposits of the Central Colorado trough provide an opportunity to examine the relationship between deformation and sedimentation in an Ancestral Rocky Mountain basin. The Central Colorado trough was a north-south trending basin bordered by basement-involved highlands of the Uncompahgre Uplift on the west, and the Ancestral Front Range and Apishapa Uplifts on the east. Measured section data show that the Central Colorado trough was an asymmetric basin, with up to 4,000 m of coarse-grained deposits adjacent to the Sand Creek-Crestone thrust system of the Uncompahgre Uplift. These deposits pinch out eastward against the Apishapa Uplift along the eastern basin margin. Lithofacies analysis shows that the Central Colorado trough was filled by fan delta, fluvial delta, and turbidite deposits of the Minturn Formation and alluvial fan, braided stream, and meandering stream deposits of the Sangre de Cristo Formation. Relative sea level fluctuation resulted in well-developed cyclicity in the deposits of the Minturn Formation. Geologic mapping has identified three syndepositional structures in the Central Colorado trough that all indicate Pennsylvanian-Permian contractile deformation. These structures include the Gibson Peak growth syncline in the footwall of the Crestone thrust fault, the Sand Creek blind thrust fault buried beneath Pennsylvanian-Permian deposits, and the Badger Creek intraformational angular unconformity. Results of this study suggest that the Central Colorado trough formed due to thrust loading from the Crestone and Sand Creek faults. The Apishapa Uplift is interpreted as a forebulge that formed in response to thrust loading along the western basin margin. The structural and depositional configuration of the Central Colorado trough appears similar to other Ancestral Rocky Mountain basins. The Paradox basin, Eagle basin, and Denver embayment were asymmetric basins with synorogenic deposits concentrated adjacent to basin-bounding thrust faults and reverse faults, suggesting a regional pattern of contractile deformation.
Degree
Ph.D.
Advisors
Ridgway, Purdue University.
Subject Area
Geology
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