--> ABSTRACT: Spectacular Exposures of Thrusting in the Core of Concentric Anticlines as Models for Oil Exploration, by Jason J. Beall; #91019 (1996)

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Spectacular Exposures of Thrusting in the Core of Concentric Anticlines as Models for Oil Exploration

Jason J. Beall

The Owl Creek Mountains are an east-west trending uplift located on the southern edge of the Bighorn Basin, Wyoming, comprised of a series of northwest-trending structures bounded by northeast-verging thrust faults. Mud Creek and Middle Mud Creek Anticlines are two basement-controlled folds located on the footwall of the Mud Creek-North Owl Creek Fault zone.

Mud Creek and Middle Mud Creek anticlines are en echelon structures which trend approximately N30W. Exposed in the Jurassic section is a series of stacked thrust faults which die out downward into bedding. These faults achieve an additional structural relief on the crest of the anticline. This has important implications for the drilling of concentric structures and reservoir distribution.

Three scenarios can possibly explain the en echelon arrangement of the two anticlines. The first calls for a single basement thrust, offset by a compartmental fault; the second possibility is two en echelon thrust faults. The third is that of a single, sinuous, low-angle basement thrust fault. This third geometry will account for the apparent en echelon arrangement of Mud Creek-Middle Mud Creek Anticlines. Additionally, an abrupt change in the trend of Mud Creek Anticline is one of the indicators of left-oblique slip on west-trending basement faults of the north of the Owl Creeks and adjacent areas.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California