Round 18 - NTGS Geophysics and Drilling Collaborations Program (Innovative Targeting): Mount Douglas Microgravity Infill Survey: GR649 (EL 31451 & EL 33075) Mount Douglas Project

Abstract

The Mount Douglas Project lies approximately 50 km east of the township of Adelaide River, and approximately 130 km southeast of Darwin, largely on BanBan Pastoral Lease. Orpheus is exploring the Mount Douglas Project principally for unconformity-style uranium mineralisation. Exploration for other commodities such as gold, tin and base metals are also being considered. Four specific exploration targeting models for uranium will be applied: unconformity-style and structurally controlled mineralisation, and mineralisation associated with thermal contact metamorphism and within specific stratigraphic units. Following on from Orpheus' participation in the GA/NTGS PCO Ground Gravity Survey in 2024, when Orpheus funded closing up of the government- funded 2km spaced points grid with close- ups to 1km and 500m over parts of their EL holdings, Orpheus applied for funding in the NTGS Round 18 Geophysics and Drilling Collaborations Program for an Innovative Targeting grant to help fund infill of the ground gravity grid spacing to 400m and 200m centres over areas of interest to Orpheus. Close spaced gravity surveys have been previously used to identify alteration zones around unconformity- related uranium deposits beneath cover, and Orpheus is targeting this style of mineralisation in structures under and around the large outlier of Kombolgie Sandstone at Mount Douglas. The grant application was successful, and this report describes the work completed. The infill survey was conducted over tenements held by Trachre Pty Ltd, a fully owned subsidiary of Orpheus Uranium Ltd, over the Mount Douglas Project area, which includes EL 31451 and EL 33075, for which Group Reporting status has been granted as GR649. The successful contractor for the work was Atlas Geophysics Pty Ltd from Perth WA, who designated it their Project P2025075. The survey was conducted using two person UTV-borne crews, supported by Landcruiser light vehicles, and utilising Scintrex CG5 or CG6 gravity meters. A total of 3,845 stations were originally planned, 678 on 400m centres, and 3164 on 200m centres. This was later reduced to 3,745 stations when some points from the 2024 survey were found to be missing from the original planning data, and with some efficiencies from re- positioning of planned points utilising AI. A total of 3700 points were collected between the start date of 9th October 2025 and 27th November 2025, when access conditions deteriorated due to increasing wet weather that limited travel and productivity. A R44 helicopter hired from North Australian Helicopters of Katherine was utilised for some points in the east of the survey area as well as over the Mount Douglas monadnock. Initial processing of the results has revealed some apparent correlation between the results and features of interest to Orpheus' exploration strategy.