High-resolution mapping using SAM surveys over the Bogada Bore gold prospect, Western Australia

Abstract

The Bogada Bore prospect lies immediately to the north?east of the Jundee gold deposit, in the north-west margin of the Archaean Yandal Greenstone Belt, Western Australia. The prospect has a long exploration history and has undergone extensive but variably effective drilling. The gold mineralisation at Bogada Bore shares many common characteristics with the Jundee and Nimary deposits, and is controlled by predominantly brittle structures, with high-grade shoots occurring along the intersection of structures, or by the intersection of structures with dacitic porphyry intrusions. Outcrop is sparse with more than 90% of the area under thin colluvial cover and regolith weathering commonly down to 50 m or more. Previous geological interpretations have been mainly generated from drilling information, with the use of geophysics limited to a single high-resolution aeromagnetic survey conducted in 1994. This survey was useful for refining the existing geological interpretation by highlighting regional structures, geological boundaries, and magnetic trends, but it failed to delineate the small-scale structures which control gold mineralisation at Bogada Bore. Sub-Audio Magnetic (SAM) surveys were trialled over the prospect area, and have been able to delineate numerous regional and small-scale structures that are shown to correlate with gold mineralisation over several areas. These surveys have also provided the basis for a new and more detailed geological interpretation in conjunction with a gravity survey and the existing aeromagnetic and drilling data.