TINDALL, S. E.¹, G. EISENSTADT², M. O. WITHJACK², and R. W. SCHLISCHE^3
1The University of Arizona, Tucson, AZ
²Mobil Technology Company, Dallas, TX
³Rutgers University, Piscataway, NJ

Abstract: Interpretation of Oblique Compressional Structures: Comparison of Field Examples and Physical Models

Scaled physical models and field studies indicate that a variety of structures previously attributed to pure dip-slip reverse faulting or pure strike-slip faulting are actually the result of oblique movement along a basement fault.

A series of physical models were constructed of 4 cm of layered clay above a 45°-dipping basement fault. They were shortened 2.75 cm at 45° to the strike of the underlying basement fault to simulate oblique compression. Resulting map-view structures include a fault-parallel asymmetrical anticline, outer-arc normal faults oblique to both the basement trend and the compression direction, and en-echelon to anastomosing oblique-reverse faults. In cross-section structures resemble those formed by dip-slip compression.

The East Kaibab monocline in Utah and Arizona, usually interpreted as the result of dip-slip reverse offset on a steeply-dipping basement fault, resembles the models in map patter Normal faults on the crest of the fold nearly bisect the angle between the fold trend and compression direction. En-echelon reverse faults accommodate a component of strike-slip offset.

Features at West Sussex-Dugout oil field, WY, the Newport-Inglewood trend, CA, and Sahil field, Abu Dhabi, UAE also resemble the oblique shortening models in map view. The ability to distinguish oblique-compressional from strike-slip or dip-slip structures allows accurate characterization of regional tectonic setting and structural style and better understanding of trap development, location, and geometry in regions of oblique deformation.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas