Brownfields exploration for possible buried economic Mesoproterozoic basement-hosted IOCG type mineralisation, so far undertaken by BHP Billiton ('BHPB') within six semi-contiguous licences together covering an area extending from 40 km south to 68 km north-northwest of the Olympic Dam mine, initially consisted only of the interpretation of available geophysical data and limited drilling data. Exploration strategies lately followed by BHPB and others in this general region of moderately deeply buried basement have involved using geophysics (predominantly through acquiring Falcon airborne gravity/magnetic, induced polarisation, magnetotelluric and ground gravity surveys, and by the interpretation of regional seismic profiles), with follow-up deep drilling. The varied geophysical data allow for making regional to local-scale structural interpretations; gravity highs with or without associated magnetic anomalies may point to haematite and/or magnetite alteration at depth, which may in turn be associated with copper-gold mineralisation as at Olympic Dam. Late during the first year of the project, in June 2013, a portion of a regional Falcon gravity gradiometer-magnetic airborne survey, amounting to 1045 line km recorded along nearly north-south aligned flight lines using a 60 m nominal terrain clearance height, was flown over the six subject licences. BHBP expected that its ongoing interpretation of the aerial gravity data in combination with the content of other datasets would clarify the company's models for several high and low priority targets identified across the central northern part of the project area, leading to further airborne data collection as either detailed infill traverses or a lateral extension of the 2013 Falcon survey. During Year 2 of the project, in March 2014, another airborne gravity gradiometer (Falcon) survey was acquired over northern Theseus to infill the 2013 flown lines there, the aim being to better define some identified targets. The infill lines were flown in two stages: Stage One had lines 600 m apart over a total distance of 1910 line km which covered ELs 4896, 4916, 4917 and 4918. Stage Two covered the two sub-blocks of EL 4897 in the south at 300 m line spacing, to tie in with the original Falcon survey that had been flown in 2006 over the Stuart Shelf tenements. Here the total distance flown was 2066 line km. A geological and geophysical assessment was completed on the Theseus Project which determined that EL 4902 Parakylia had low prospectivity. Thus it was chosen in its entirety for meeting the annual 10% compulsory relinquishment of licence acreage as per the terms of the Amalgamated Expenditure Arrangement agreed with DMITRE in 2013. EL 4902 was therefore not flown during the 2014 Falcon survey. During Year 3 of the project, geophysical forward modelling of the 2014 Falcon survey data was performed for BHPB by consultant Jim Hanneson. A single detailed model was completed for what was regarded as being the most prospective area, and three preliminary models were done for targets located in the northern Theseus tenements. Interpretations suggested that two of the preliminary models were geologically implausible, while the remaining two models had credibility. During Year 4 of the project, the main targets in the Theseus tenements were re-ranked using the BHPB Copper Exploration Prospectivity Analysis template. This prospectivity analysis assigns prospectivity levels within a terrane to indicate the potential of the geological environment to contain a deposit of required size. Firstly, a prospectivity map was created of the Olympic Domain, which identified terrane boundaries creating segments between major faults. Baseline prospectivity was determined using metallogenic endowment, basement geology age and exhumation level. Areas were upgraded where overlapping fault intersections and deep magnetic bodies were identified. Magnetic data were used in preference to gravity data as they have a more even coverage over the area. The prospectivity map was then considered jointly with the Geological Observations (alteration and mineralisation) to rank the targets. During Year 5 of the project, from April to May 2017, a 2D MIMDAS-IP survey was conducted within the southern part of the Theseus North ELs 4916,4917 and 5958 by Geophysical Resources and Services, near the Hidden Swamp salt lakes, ~50 km north-west of the Olympic Dam mine. The survey consisted of 5 lines ~7.6 km long bearing 80 degrees, spaced 2 km apart, for a total coverage of 38 line km. The MIMDAS recording station configuration was a 200 m pole-dipole array, used to provide maximum depth penetration of the inductive current. The MT component of the survey had a remote station 30 km away, and a remote pit 4 km away for telluric cancellation. Survey data QA/QC was performed by the GeoDiscovery Group in June 2017 [see included reports]. From extensive modelling of the survey data, it was determined that the MIMDAS method did not have the capabilities to see through the thick cover (500 m to 1 km thick) to the basement units, nor could it detect any chargeable zones below a ~150 m thick conductive layer in the cover, the presence of which was evident from the transformed IP data. Consequently, BHPB believed that the survey did not identify any anomalous bodies in the basement, or any shallower conductive or chargeable targets that they would consider for follow up drilling. BHPB commissioned Mira Geoscience to model a 3D Solid Earth Geology regional interpretation of the Stuart Shelf to assist them with their mineral system approach to IOCG targeting, where gravity and magnetic highs were understood from either a lithological alteration or mineralisation perspective. This work will target more subtle potential field anomalies that also exhibit evidence of additional, coincident critical geological processes. This work was still in progress at the time of reporting. During Year 6 of the project a heritage survey was undertaken with three Indigenous ODA signatories to allow for the collection of a regional Magnetotelluric (MT) survey. The regional MT survey included the collection of 60 soundings covering the majority of EL 5959 and was collected by Zonge Engineering and Research Organisation between November 2017-March 2018, with QAQC completed by both Zonge in their Adelaide office and CGG in Milan. A ground gravity surveys with a total of 2,541 stations was collected on a 250 x 250 m grid over two prospects: Acropolis West and Aphrodites. The survey was completed by Daishsat Geodetic Surveyors between February to April 2018, with the aim of the work being to acquire higher resolution data that could assist with the interpretation of subtle gravity variations identified in the 3D model. The 3D solid earth geological model developed in the previous reporting period was updated with information from structural and geological models, while the cover geology was also reinterpreted and updated as the significance and effect of it was further realised during the modelling.