A dextral strike-slip model for the Miri Structure

Abstract

The Miri Structure shows complex geometry as a result of interplay between compression and tensional wrenching. Evidences for strike slip deformation are illustrated. These include the presence of: 1. En-echelon normal fault arrangements along a major fault with dominant normal throw (Shell Hill Fault), often accompanied by reverse fault throws and dip reversals along individual faults showing the following features: • Conjugate fault systems (synthetic and antithetic) • Small-scale faults showing negative and positive flower structures • Oblique and down-dip striations • Ribbon effect geometry 2. A dextral strike slip fault zone named the Canada Hill 'Thrust' Zone, characterized by: • Sub-horizontal striations • Fault zone associated with both compressional and extensional structure • Thrusts and extensional faults showing cross-cutting relationships in a single section 3. Presence of push-up block/ridge bounded by the Shell Hill Fault and Canada Hill Thrust zone. 4. Curved horse-tail configuration. The main conclusions from this study are as follows: 1. The 4 sets of structural elements associated with the Miri Structure are coeval. 2. They are the result of a progressive NNE-trending dextral strike-slip deformational event. Dextral strike-slip movement could have initiated early prior to lithification and continued after lithification.