URL: https://geoscience.data.qld.gov.au/dataset/cr124478
Rio Tinto Exploration Pty Limited (RTX) relinquished 32 sub-blocks from EPM26960 ‘Wills9’ on the 6th May 2021. The tenement lies within the Millungera Basin, extending approximately 250km north-south and 85km east-west. Initial prospectivity review was focussed on gravity anomalies along or close to the Cover Sequence 4 (CS4) unconformity. RTX previously conducted exploration activities in the surrounding area and identified the potential for large scale IOCG mineralisation in the region.
The targeted gravity anomaly appears to be under approximately 350m of younger cover and the intensity is consistent with IOCG hematite alteration. Historically, IOCG mineralisation was believed to be restricted to Cover Sequence 2 and 3, while Cover Sequence 4 was not previously considered permissive for hosting IOCG mineralisation. However, new age dates suggest Cover Sequence 4 is permissive. Being higher in the paleo-setting, Cover Sequence 4 might also host larger IOCG breccia complexes and if so, they are more likely to be hematitic rather than magnetite bearing.
In the 2019-2020 a ground gravity survey was collected within the surrounding tenements partially overlap with two relinquished subblocks. The data confirms a regional gradient across the license area, with the gravity field dropping by ~14 mGal from southeast to northwest. First vertical derivative data identified some potential structure and variation within the block, however due to broad low-gravity and magnetic gravity and absence of any other indicative of IOCG-style mineralisation within elected relinquished sub-Blocks RTX decided voluntarily to relinquish 32 subblocks as outlined in this report. No other exploration work completed within the relinquished sub-blocks.