Following the first public announcement on 18/11/1976 by Western Mining Corp. of its giant Olympic Dam copper, gold and uranium discovery on Roxby Downs Station, Newmont Pty Ltd began a detailed assessment of the Stuart Shelf region of South Australia. Although the latter company did not yet know the nature of the mineralisation or controlling host strata at Olympic Dam, it swiftly made application to the SA Department of Mines for the grant of exploration licences over available ground located north-west of Olympic Dam, selecting areas occupying a trend that lay to the east of the Torrens Hinge Zone (THZ). The subject Margaret Creek area was chosen because it covered coincident broad regional gravity and magnetic anomalies that are situated close to the intersection of an east-northeast trending geophysical lineament and the THZ. Newmont entered into a 50:50 joint venture partnership with BHP subsidiary Dampier Mining Co. early in 1977, and EL 335 was granted to both companies in the middle of that year along with six other Exploration Licences covering adjoining ground in the Anna Creek - Mount Woods region which looked to have a similar geophysical character, and which lay over a linear crustal feature that appeared to link major copper deposits further south (Olympic Dam, Mount Gunson and Moonta-Wallaroo). Within the Newmont-Dampier exploration project area, the target sought was of Olympic Dam type, i.e. large tonnage, low grade primary Cu-U mineralisation occurring in or near to a crystalline basement host. Initial field activities commenced in August 1977, with the acquisition of detailed ground magnetic and gravity surveys over regional geophysical anomalies, which in the case of EL 335 comprised the One Tree Bore and Mount Morgan gravity anomalies. Prospect grids were surveyed there and reconnaissance hand-held magnetometer readings were taken at 250 m intervals along principal traverses. Solo Geophysics were contracted during September 1977 to take gravity readings at 250 m x 2500 m station spacing over both anomalies (99 readings on each grid respectively). On each grid, a preferred drill site for conducting a stratigraphic test was picked by Newmont's chief geophysicist. Drilling was begun in mid-October 1977, when vertical rotary mud precollared and then NQ/BQ diamond cored stratigraphic/exploratory hole SR6 was taken to 550.0 m total depth on the Mount Morgan anomaly, reaching TD on 31/3/1978. This hole ended within the Tapley Hill Formation, having passed through a thick section of Upper Adelaidean strata only thinly covered by Mesozoic to Recent sediments. No significant mineralisation was encountered. There were indications of oil shale horizons in the Mesozoic cover sequence. Heavy rains that occurred for the rest of 1978 delayed progress on vertical hole SR8 at the One Tree Bore anomaly, which had been rotary mud precollared to 100.6 m depth late in 1977. During 1978, Newmont carried out office-based regional basin studies to inform its stratabound, African Copperbelt style epigenetic mineralisation model. Using stratigraphic data from water wells and other boreholes, thickness estimates were made for the local Recent to Palaeozoic cover sediments. An in-house study of 1:100,000 scale aerial photomosaics and Landsat images was performed to map lineaments over a wide prospective belt running northward along the Torrens Hinge Zone from Moonta to the northern end of the Stuart Range Project acreage, and the aforementioned prominent NNW-trending lineament was clearly identified. The intersecting pattern of lesser lineaments observed around Mount Gunson and Olympic Dam appeared to be repeated along strike on the eastern side of EL 335. Early in November 1978, drillhole SR17/2 was begun at Joe's magnetic anomaly, a large feature which extends from the eastern side of EL 335 onto the JV's adjoining EL 441. This hole was percussion precollared to 200 m before being continued with HQ/NQ/BQ diamond coring until drilling was suspended at 934.8 m depth, close to the capacity of the rig then in use. This same rig was then shifted onto previous hole SR6 and was used to deepen it from 550 m to 889.55 m depth by April 1979, when the drilling here was also suspended. At this stage, both of the cored holes still remained within Adelaidean glacial sediments. During November 1978, gridding and the acquisition of ground magnetic and gravity survey data were undertaken at the small Turret gravity anomaly located 10 km north of Joe's Dam (85 gravity stations read at 250 m x 2000 m precision). During the first half of 1979, Newmont assessed the results so far obtained from its two deep diamond cored holes at Margaret Creek, and compared the stratigraphy that it had encountered there against the newly revealed type of cover rocks from the Roxby Downs Station region that it was able to log during an inspection it made of WMC's drillcore from the RD16 hole recently put in at Olympic Dam. This work showed the company that it must continue drilling much deeper on its own ground to penetrate below the Adelaidean sedimentary sequence and reach prospective basement, and that it would need to develop a conceptual tool for evaluating structural and geophysical anomalies prior to doing deep drilling. Therefore Newmont immediately made plans to conduct seismic reflection surveys on its project licences, particularly on the Margaret Creek licence once it was renewed for a second term. At a meeting of the three JV partners held in June, it was further resolved to deepen hole SR17/2 at Joe's anomaly to a depth of 1400 m. Following both of these costly decisions, which it did not support, BHP elected to withdraw from the joint venture. Also during this period, the groundwater outflows from certain artesian mound springs which lie within the EL 335 area were geochemically sampled for dissolved pathfinder elements which might point to the proximity of target mineralisation, but no significant assay values were obtained.