--> Abstract: Role of Tectonics in Regional Progradation of Coarse-Grained Sequences: Upper Cretaceous Castlegate Sandstone, Charleston-Nebo Salient, Utah, by Brian K. Horton, Kurt N. Constenius, and Peter G. DeCelles; #90039 (2005)

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Role of Tectonics in Regional Progradation of Coarse-Grained Sequences: Upper Cretaceous Castlegate Sandstone, Charleston-Nebo Salient, Utah

Brian K. Horton1, Kurt N. Constenius2, and Peter G. DeCelles2
1 University of California, Los Angeles, CA
2 University of Arizona, Tucson, AZ

Difficulty in evaluating the role of tectonics in foreland basins originates from unresolved issues regarding the age of thrusting, location of principal flexural loads, identity of thrust sheets contributing sediment, and synchroneity of thrusting and deposition. These obstacles can be overcome by analysis of the proximal basin where contractile growth structures may be widespread and well preserved. In this study, analyses of sedimentology, provenance, palynology, and surface structure of the proximal Cordilleran foreland basin system of central Utah (U.S.A.) are united with newly released reflection seismic and borehole data to determine the influence of tectonics. Results indicate that voluminous, coarse-grained, quartzose detritus was introduced into the basin during a Campanian episode of shortening and uplift. Debris was eroded from Pennsylvanian-Permian Oquirrh Group rocks forming the roof of a duplex system (Santaquin culmination) in the Charleston-Nebo salient of the Sevier thrust belt. Deposition coincided with the generation of thrust-related growth strata, culmination uplift, and pronounced eastward progradation of the Castlegate Sandstone across the Book Cliffs region of eastern Utah. We propose that tectonic evolution of the Charleston-Nebo salient exerted a central influence on sequence development in the Book Cliffs by providing the primary sediment source and producing the bulk of flexural accommodation. Forward modeling of basin subsidence is achieved through incremental restoration of a balanced cross section. Flexural models suggest that eastward advance of topographic loading was inhibited during Campanian time, reducing the generation of accommodation in the proximal basin and facilitating progradation >200 km eastward from the thrust belt.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005