Geological and geochemical aspects of the Liontown VHMS deposit North Eastern Queensland

The Liontown VHMS deposit lies in the central portion of the 165km long, E-W trending, narrow belt of deformed Cambro-Ordovician marine sediments and volcanics known as the Mount Windsor subprovince of northeastern Queensland. Liontown is shown to be a volcanic-associated massive sulphide deposit comprising both seafloor exhalative and subhalative mineralisation. Metal zonation studies suggest the exhalative mineralisation was vented onto the seafloor on the edge of a paleo ridge and migrated down slope to the west and southeast. Sulphur, lead, oxygen and carbon isotope data is consistent with a VHMS parentage. The Liontown deposit is temporally associated with the change from dacitic to rhyolitic volcanism and may have a more shallow water setting than previously considered. The Carrington Lode at Liontown is a sub-seafloor replacement body interpreted to have formed by the eastward lateral migrat"i on of hydrothermal fluids preferentially through an ashy and feldspar bearing volcaniclastic horizon. The associated black Mg-chlorite alteration is infered to mark a zone of seawaterhydrothermal fluid mixing. The application of stable isotope and rare earth element (REE) analyses to provide "vectors" to mineralisation is invesigated in the thesis. The whole rock oxygen isotope data collected along the footwall alteration system indicates that this technique has good vectoring potential to zones of elevated hydrothermal temperature. Refinement of the raw data through the calculation of relative temperature estimates is demonstrated as an important data manipulation procedure, particularly for data sets where the sample mineralogy is highly variable. The Liontown carbonate exhalative facies and the sericitic siltstones of the 'favourable horizon' each have positive europium anomalies (Eu/Eu*>l). In the immediate Liontown deposit area a proximal to distal trend was observed in the carbonate europium data set suggesting there is some scope to develop the intensity ofEu/Eu* as a vectoring tooL