Sunrise Dam Gold Mine, Western Australia: mechanical controls on an Archean lode gold hydrothermal system

Abstract

The Sunrise Dam Gold Mine is the largest gold deposit in the eastern part of the Yilgarn craton. In several ways it is a typical Archean lode gold deposit, other than its exceptional size. Mineralization is hosted in intermediate-mafic metavolcanics and metasedimentary rocks. The major structures are gently NW to NNW dipping shear zones, which are connected by sub-vertical NNE and NE trending fault and breccia zones. Ore bodies occur parallel to the shear zones and faults. At least 6 deformation events can be distinguished. The majority of the gold mineralisation occurred in D3 and D4, with some also possibly occurring in the first event. The two major deformation/ mineralizing events had strike slip kinematics, reflecting SE and NE shortening respectively. Two key mechanical factors in the formation of the Sunrise Dam deposit were reactivation, and the existence of structures and competent bodies that caused stress perturbations. The identification of these factors could have useful exploration implications.