ABSTRACT: 3-D Modeling of Fault-Related Folding, McConnell Thrust Sheet, S.W. Alberta

DOBSON, JAMES M. M., PanCanadian Petroleum Ltd., Calgary, Alberta, Canada, and KEN R. MCCLAY, University of London, England

The Highwood Range in the Front Ranges of the Southern Canadian Rocky Mountains provides excellent 3-D exposures of thrust-related folds that occur at the leading edge and southern lateral tip of the McConnell Thrust System. In recent years, a number of theoretical models have been proposed for the geometries of fault-related folds in compressional terranes. The excellent exposures in the Highwood Range have permitted an analysis on the validity of such geometric models and their assumptions. These theoretical models are limited to 2-D but their Eulerian and self-similar extrapolation in 3-D has been postulated. The detailed structural analysis of the folds exposed in the Highwood Range has revealed that the majority of outcropping folds are either fault propagation, transported fault propagation, or detachment folds. In 2-D, these structures show a close resemblance to the theoretical models. Any geometric discrepancies are interpreted to be caused by continued horizontal shortening and shearing after the initial emplacement of the structure. In 3-D their geometry and spatial distribution significantly varies along strike. As a result of the fold structures having a close compliance with the assumptions of the 2-D models and yet not displaying a self-similar style in 3-D, a model for the 3-D spatial relationship between transported fault propagation, fault propagation, and detachment folds at the lateral tips of faults has been developed.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)