Mainly magnetics: Mathinna beds and gold mineralisation in NE Tasmania

Abstract

Gold-bearing quartz reef systems within the Lower Palaeozoic Mathinna Beds metasediments of NE Tasmania have been mapped magnetically even though magnetic contrasts are small. High-resolution airborne surveys have resolved differences between the granitoids which intrude the host sequence, and an array of structures within the host rocks. All known mineralized areas studied appear to be associated with one member of the granodiorite family, and with particular structural orientations. Detailed ground surveys can define the volume of altered or potentially mineralized host rocks, and relate local vein orientations to the more regional controls. Vein systems are themselves mappable magnetically owing to oxidation along the vein walls, which produce spike responses.