ABSTRACT

The Arapien basin is situated along the hinge line in central Utah between the Wasatch Plateau to the east and the Canyon and Pavant Ranges to the west. The basin was initially described from the extensive exposure of Jurassic shale and evaporites in the Arapien Valley. Subsequent drilling and seismic profiling revealed thick zones of structurally complex strata beneath the ranges and great depths of sediment fill in the central valleys.

The concept of the Arapien basin and consequent exploration strategies are dependent on how the sequence and importance of structural events in central Utah are envisioned. New ideas include: (1) the concept of stratigraphic thickening from shelf to miogeosyncline across the hinge line includes the Arapien basin as a partially enclosed, graben-type basin subject to desiccation and evaporative deposition, (2) the concept of salt diapirism and salt solution collapse, which has figured prominently in the thinking of some recent workers, (3) the full acceptance of Sevier thrusting, which brings into focus the uniform timing of compressional events in central Utah and thickening of strata by tectonic duplication, and (4) the concept of basin and range extension which is now accepted by many geologists. The reality of listric block faulting and back sliding explains the tilted Tertiary strata on the ranges and the anomalously thick strata in the valleys.

Sorting out the sequence of structural events in the Central Utah hinge line is clearly needed to formulate exploration strategies in the Arapien basin. The abundance of shows in the Wasatch Plateau and the projected extension of overthrust structures south into the area warrant continued interest.

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