A multi-disciplinary characterisation of Heath Steele belt deposits, Bathurst Mining Camp: a basis for identifying new targets for the exploration
Although the Bathurst Mining Camp has been explored for more than 40 years, high-resolution airborne geophysical survey has led to the detection of several new volcanogenic massive sulphide occurrences in the region. The discovery of these concealed exploration targets depended directly on the knowledge of the multi-parameter signature of the major deposits and the search for the repeatability of these signatures in other regions. The Heath Steele B deposit, within the southern part of the Bathurst Mining Camp, together with an associated magnetite-rich iron formation and adjacent tuffaceous sedimentary rocks, produced strong, co-extensive magnetic and conductivity anomalies. However, the strong anomalies observed in the geophysical data can be related to non-mineralised lithology such as mafic dykes or graphite. So a direct identification of exploration targets using geophysical data only can be difficult. For this reason, the joint interpretation of geophysical and geochemical signature can considerably improve the identification of new deposits. Using these techniques, we identify three new possible targets, characterised by local magnetic and apparent conductive highs. Two of these areas are located in the Heath Steele belt, and their geochemistry has been studied in detail. The proximity of these targets (less than 1.5 km) from known occurrences of hydrothermal sediments (magnetite, siderite, and stilpnomelane) confirms their exploration potential. The fourth identified area is most likely associated with a regional anomaly related to an unmapped ferromagnetic structure and was earlier disregarded as a possible target. The joint interpretation of geophysical and geochemical data allowed us to identify two new targets for exploration and to exclude one area interpreted as associated with a regional anomaly. Therefore, the search parameters (physical proprieties and hydrothermal sediment geochemical pattern distribution) are established with a success index of 75%. The index was limited by the absence of geochemistry data over the third target. The procedure presented in this paper can be used to search for new targets elsewhere in the Bathurst area and even in other base metal regions.