Sulphide mineralization and host rocks of the Kangiara region, New South Wales

The Kangiara region, in south-eastern New South Wales, forms part of the Lachlan Fold Belt. The region is underlain predominantly by acid volcanic rocks (the Hawkins Volcanics) of Silurian age with minor intercalations of limestones, shales and sandstones, deposited on a continental margin in a partly marine environment. Study of 209 thin sections and 89 whole rock chemical analyses shows that the Hawkins Volcanics consist of siliceous, potassium-rich calc-alkaline pyroclastic rocks varying in composition from dacite to rhyolite. Detailed investigation of the base-metal sulphide mineralization in the region, including mineragraphic examination of 411 polished sections, 610 electron microprobe analyses and trace element determinations on 95 sulphide mineral separates, indicates that four main types of deposit are present: Kangiara-type in the Hawkins Volcanics; mineralization at Rays prospect on the contact between Hawkins Volcanics and Mundoonen Sandstone; mineralization in limestone and calc-silicate hornfelses; and mineralization in metamorphosed Ordovician sedimentary rocks.