Report on 1973 investigations EL 281 Nourlangie and Goanna Creek

Abstract

The main aim of the 1973 field programme was to delineate the most prospective areas for retention when reductions were required at year's end. It was therefore planned to continue regional geological mapping, supplementing surface data by auger drilling. Increasing knowledge of the geology of the new uranium discoveries in the Alligator Rivers region had suggested that rocks near the margins of the Nanambu Complex, particularly a lithological unit currently termed 'Koolpin Equivalent' by BMR geologists, are favourable host rocks for uranium mineralisation. Efforts were therefore made to identify these and trace them along strike. Extensive geochemical sampling of stream sediments and auger cuttings was carried out in conjunction with the geological work. One anomaly, Anomaly 95, not previously examined in detail was mapped and evaluated by auger and percussion drilling. Late in the season an airborne radiometric and magnetic survey was flown over an area of approximately ninety square miles in the eastern part of the Exploration Licence. The survey was flown at a flight line spacing of about one thousand feet utilising more sophisticated radiometric equipment than had been available for previous surveys. This survey covered Nanambu Complex margins, previously indicated by auger drilling. Conclusions - Prospecting in Exploration Licence 281 during 1973 failed to locate any economic mineralisation. Geological and radiometric investigations, however, have outlined a potentially uranium-bearing zone within the Koolpin Equivalent rocks close to the Nanambu Complex contact. The Koolpin Formation rocks which outcrop in the western part of the Exploration Licence may also be a favourable host for uranium mineralisation.