Sequence Stratigraphy and Facies Architecture of the Desert Member of the Blackhawk Formation and the Castlegate Formation in the Book Cliffs of Eastern Utah and Western Colorado
John C. Van Wagoner, 1991. "Sequence Stratigraphy and Facies Architecture of the Desert Member of the Blackhawk Formation and the Castlegate Formation in the Book Cliffs of Eastern Utah and Western Colorado", Sequence Stratigraphy Applications to Shelf Sandstone Reservoirs: Outcrop to Subsurface Examples, J. C. Van Wagoner, C. R. Jones, D. R. Taylor, D. Nummedal, D. C. Jennette, G. W. Riley
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The Desert Member of the Blackhawk Formation and the Castlegate Formation are well exposed along the Book Cliffs in eastern Utah and western Colorado. The cliffs are oriented relative to the southeasterly paleotransort direction within the Desert and Castlegate so that outcrops expose both strike and dip views of these strata] units. Starting in Tuscher Canyon outside of Green River, Utah and ending in West Salt Creek Canyon, one can traverse the Castlegate and Desert from a totally nonmarine depositional environment updip to shelf mudstones, in the case of the Desert, and red, ferruginous oolites in the case of the Castlegate downdip. Three sequence boundaries are developed in the interval, one within the Desert and and two within the Castlegate. Because of the high-quality of the exposures, the superb access to the rocks, and the orientation of the cliffs, these two units provide an unsurpassed natural laboratory to study nonmarine to marine sequence stratigraphy. Variations in sequence-boundary expression from updip to downdip, systems tract variations across a basin, changes in incised-valley geometries, and fluvial architecture in nonmarine lowstand deposits can all be analyzed in the Castlegate and Desert
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The Lower Sego provides an opportunity to study well-exposed, high-frequency sequences and their systems tracts. Criteria for identification of sequence boundaries will presented. Sequences and their boundaries will be contrasted with parasequences and their bounding surfaces. The Upper and Lower Sego contain well-exposed tidal deposits within the lowstand systems tracts of high-frequency sequences. These tidal deposits and their relationship to incised valleys and systems tracts will be examined. The incised valley interpreted to form during relative falls in sea level will be contrasted with distributary channels related to autocyclic mechanisms.
0.0 Leave the parking lot of the Grand Junction Hilton. Grand Junction , Colorado. Turn left onto Horizon Drive. Pass under the 1-70 bridge, Turn left into the entrance ramp for 1-70 west.
0.2 Enter 1-70 heading west toward the Colorado –Utah State line. For the next 20 miles the Interstate will parallel the Colorado River flowing along the west side of the Grand Valley. The Interstate is built on the gray Cretaceous Mancos Shale. To the west of the Colorado River are the red cliffs of the Colorado National Monument. The Monument is operated by the National Park Service. These cliffs are the eastern edge of the Uncomahgre Uplift. As you drive north along the Interstate, the steeply dipping eastern limb of the Uncomahgre is clearly visible. This tight monoclinal fold is the result of horizontal compressional tectonics associated with Laramide deformation (Heyman, 1983). The red rocks in the Mounment include, from stratigraphically oldest to youngest: the Chinle Formation forming the lower, less resistant slops, the Wingate formation forming the massive cliffs up to 400 feet thick , the Kayenta Formation overlain by an unconformity along which the Navajo and Curtis Formations are missing , the Summerville and Entrada Formations, and the Morrison Formation consisting of fluvial sandstones and associated mudstones, within which some of the earliest dinosaur bones in North America were discovered in the late 19th century. The Jurassic Morrison Formation is unconformably overlain by the brown, Cretaceous, coal-bearing Dakota Sandstone. The Dakota caps many of the high mesas within the Mounment and forms well-exposed dip slopes along the Interstate in the vicinity of the exit to Mack, Co..