--> Abstract: 3-D Structural Model of Structures along the Western Margin of the Bighorn Basin, Wyoming; #90063 (2007)

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3-D Structural Model of Structures along the Western Margin of the Bighorn Basin, Wyoming

 

Banerjee, Subhotosh1, Shankar Mitra1 (1) University of Oklahoma, Norman, OK

 

The western margin of the Bighorn basin, Wyoming, is marked by a series of basement-cored anticlines formed along steep, easterly-dipping reverse faults. These-second order anticlines, such as the Rattlesnake Mountain and Hamilton Dome anticlines, are characterized by short steeply-dipping forelimbs and long, gently-dipping back limbs. The cover rocks involved in the deformation consist of alternating clastic and carbonate sediments of Cambrian to late Cretaceous age above Precambrian granitic basement. Three-dimensional geologic models have been constructed in the Rattlesnake Mountain anticline (RMA) and Horse Center anticline (HCA) areas, for the Jurassic Gypsum Springs and Pennsylvanian Tensleep Formations and the Basement. The models are constrained using a series of eight cross sections, well tops from more than 200 wells, dipmeter data from 22 wells, surface geologic maps, detailed field mapping, and remote sensing data using color infrared digital orthophotos. The Rattlesnake Mountain Anticline (RMA) and adjacent Horse Center Anticline (HCA) show complex branching and lateral terminations of anticlinal axial traces. Based on the 3-D modeling, these second-order structures are interpreted as back-limb structures on a first order anticline. Relatively smaller scale secondary detachment folds, which detach in the lower Cretaceous shales are present on the east-dipping back limb of the RMA. These include several producing structures such as the Cody, Shoshone and Shoshone North fields, which produce from the Cretaceous Frontier, Permian Phosphoria, and Pennsylvanian Tensleep formations. Understanding the 3-D geometry of these structures is critical in unraveling the structural evolution of the Bighorn Basin and in interpreting trap geometries in the Rocky Mountain Foreland basins.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California