Three large but quite separate licence areas located at the southern end of the Frome Embayment have been explored together for possible economic buried sedimentary uranium mineralisation hosted by Tertiary palaeochannel sands of the Callabonna Sub-basin. Activity in the first year of the project began with a literature search of references describing the genesis of uranium deposits within sandstone strata, plus the conduct of a detailed review of past exploration done in the region. This was followed by the acquisition of ground gravity and airborne EM surveys, to investigate the distribution of sediments and palaeodrainage features in what Afmeco considered were previously under-explored areas, such as particular zones along the Erudina and Lake Namba Palaeochannels where the sediments had not yet been tested by drilling. The historical exploration records for the subject area that were examined by Afmeco highlighted several factors existing there that it thought are favourable for finding sediment-hosted uranium mineralisation associated with redox chemistry transition zones: - the presence of valley-fill Eyre Formation channel sands that, going basinwards, extend beyond the palaeochannel boundaries to cover the local palaeotopography (as sheet sand units); - the development of a secondary, mobile oxidation front within the originally reduced Eyre Formation sands; - the existence of radiometric anomalies in the Eyre Formation; and - the presence of sub-economic uranium mineralisation at the Gould’s Dam prospect in the vicinity of EL 3167. During July-August 2004, Fugro Airborne Surveys were contracted to fly a TEMPEST EM survey over all three licences. Respective totals of 1259.7, 1233.3 and 900 line km of AEM data were acquired along east-west flight lines spaced 1 km apart, using a 110 m sensor height above the ground surface. The recorded data was of good quality, and when it was converted to sections displaying conductivity depth imagery, it appeared that significant buried porous palaeochannel sequences filled by saline groundwater are present on each licence area, although the survey flight line spacing used had prevented a precise definition of their boundaries and thickness. To achieve better mapping of the Tertiary palaeodrainage features, Afmeco proceeded to acquire semi-detailed ground gravity coverage within ELs 3167 and 3168 during September-October 2004, when Haines Surveys read totals of 3306 and 5755 new gravity stations respectively on offset 500 m x 100 m grids located to the north-east and east of Erudina Homestead. However, results from both surveys proved confusing and the distribution of low density anomalies did not appear as expected. A consultant was employed to study whether making terrain corrections might improve the gravity data interpretation, but his conclusion was that their effect would be negligible in helping to sharpen the observed Bouguer anomalies. In the second year of tenure, Afmeco continued its ground gravity acquisition, this time over EL 3168 to try to delineate the Lake Namba Palaeochannel. During October 2005, 5350 new stations were read over an irregular 500 m x 100 m grid by Haines Surveys. During September 2005, GPX Airborne were contracted to fly a trial HoistEM survey over part of the Stickhole Palaeochannel located south-west of Frome Downs Homestead, for the purpose of comparing this type of EM data with that acquired by the 2004 TEMPEST survey. Six east-west lines spaced 500 m apart were flown for a total 72.7 line km, along the same flight path as previously used, and included some infill lines. Whilst the HoistEM results were found to compare favourably with the TEMPEST results, there was a noticeable depth limitation with the HoistEM system. It was concluded that, within this immediate environment, HoistEM could not be expected to penetrate deeper than about 80 m below surface. Further interpretation of the extensive TEMPEST survey data was performed by Afmeco, which for all the licence areas outlined a number of probable meandering palaeochannel trends at varying depths within the Tertiary sediments. It was realised, though, that some of the more permeable palaeochannel sediments may actually contain fresh groundwater, rendering them transparent to the EM method. Comparison of the Lake Namba Gravity Survey residual anomaly map with the TEMPEST data - generated CDI sections from EL 3169 showed an excellent correlation of gravity lows with probable palaeochannel conductive responses. During the third year of activity, a vertical rotary mud drilling and wireline geophysical well logging campaign was carried out on all three subject licences in order to test AEM and gravity targets. During the period June to December 2006, 18 holes for a total penetration of 3004 m were completed on EL 3167, 30 holes for 5114 m were completed on EL 3168, and 40 holes for 3747 m were completed on EL 3169. The drilling done on EL 3169 confirmed the location of palaeochannels inferred from geophysics, including a previously undiscovered palaeochannel named the ‘Coolibah Palaeochannel’. Drilling done on ELs 3167 and 3168 intersected a few channel sands, but only one is associated with a TEMPEST data feature, and probably corresponds to the Erudina Palaeochannel. Ground gravity data appears to be more reliable than AEM data for using to help locate channel sands on EL 3168. In order to constrain the ages of the Tertiary sediments intersected by the drillholes, a few samples located in the lower part of that sequence were selected for palynological analysis. The darker sediments were chosen as they were more likely to be rich in organic matter. All of the samples were collected on EL 3168. The main age determined from their palynoflora is Middle to Late Eocene, indicating that the sediments studied belong to the Eyre Formation. The highest radiometric anomalies were encountered on EL 3169, associated with reduced sediments. Channel sands encountered on EL 3169 are strongly reduced, with abundant pyrite. Some of the darker sediment samples located at the base of the Tertiary sequence were analysed to try to determine the nature of their contained carbonaceous matter. As some seemed to be impregnated with an oil-like substance, qualitative GC chromatography was performed on these at AMDEL. Unfortunately, the poor quality of the samples made interpretation of the results difficult. Two samples were also sent to Geotechnical Services Pty Ltd in Western Australia for undergoing Total Organic Carbon (TOC) determinations and Rock Eval pyrolysis. Their contained organic matter was found to be mainly Type III kerogens, a maceral class that is derived from more highly-evolved plant forms. On EL 3167, the Tertiary sediments intersected, which were interpreted in most instances to belong to the Namba Formation, are mainly composed of clays and silts with rare sand intervals up to a few metres in thickness. A remarkable white to grey and green carbonate-rich horizon located in the middle part of the sequence was intersected in every hole excepted on line G. It is locally very hard and up to 10 m thick. It may correspond to the Upper Carbonate depositional level described by Callen (1975). This distinct unit dips towards the west and becomes thinner towards the south (absent in southernmost line G). Only one drillhole (ER0007) located on line G intersected a significant sand interval (15 m thick) at the base of the Tertiary sediments. The topography of the base of the Tertiary suggests that the sand fills an incised palaeochannel and therefore is part of the Eyre Formation. This sand is neutral to reduced, with no gamma ray log anomaly. The TEMPEST data conductivity depth slice at 160 m shows a north-south feature coinciding with ER0007, which could denote the orientation of the palaeochannel. The pre-Tertiary formations were identified as shales, mudstones and psammites of probable Cambrian age. The pre-Tertiary contact generally dips towards the west. A topographic high of this contact was noticed in ER0015 and ER0017, which could correspond to a north-south feature. It may correspond to the historically defined Erudina Palaeochannel. The shallower AEM features targeted were found not to correspond to any paleochannel sands, but rather to conductive clays. Two radiometric anomalies of >1000 cps were intersected in drillholes ER0002 and ER0003. The anomalies are located in the reduced basal part of the regional carbonate-rich horizon. They correlate with an increase of gamma activity found in other holes at the same stratigraphic level. This may be interpreted as uranium enrichment in a paleosol characterised by calcrete development and organic matter enrichment. On EL 3168, the Namba Formation sediments intersected are mainly composed of clays and silts with rare sand intervals up to a few metres in thickness. The abovementioned white, westwards-dipping carbonate-rich horizon was intersected in the upper part of the Tertiary sequence in every hole, with a thickness varying between 10 and 15 m. Several drillholes intersected Eyre Formation sands. Comparing the total sand thickness in each hole with the residual gravity anomaly map showed that sand thickness tends to increase where residual gravity values decrease. More specifically, holes ST0019, ST0028 and ST0009, which have thicker sand intervals than surrounding holes, are located on gravity lows. However, the targeted AEM features do not correlate with these sand channels. The continuity of the basal sand on line J-P suggested that it may represent the onset of the “blanket sands” which extend towards the north-northeast. The thicker sand interval and lower base of Tertiary in hole ST0024 also suggested the presence of a paleochannel. Several of the sand intercept from the Eyre Formation are reduced (ST0021, ST0023, ST0009, ST0028, ST0019, ST0014). Reduced sand zones are generally characterised by a dark brown colour locally associated with a hydrogen sulphide odour. Millimetric-size pyrite aggregates are occasionally observed. A few minor radiometric anomalies were intersected (maximum 750 cps) at redox contacts between clay and sand. One anomaly (maximum 440 cps) is located at a redox contact in sands intersected by hole ST0023. The presence of recycled palynomorphs from older sediments (Early Cretaceous age) in Eyre Formation samples suggest that the pre-Tertiary formations are of Cretaceous age. They were identified as mudstones, fine-grained sandstones and shales. The pre-Tertiary contact generally dips towards the west. On EL 3169, the Namba Formation sediments intersected are mainly composed of clays and silts, but also contain significant sand intervals up to 25 m thick in the lower part of the formation. These sands are generally unaltered, or else are locally reduced. Most of the channel-like TEMPEST AEM features were confirmed to be sand paleochannels of the Eyre Formation. Lows on the residual gravity image show a relatively good correlation with the 40 m conductivity depth slice anomalies. Drilling results obtained from holes LN0025 to LN0040 showed that the Lake Tinko and Lake Namba paleochannels defined in the 1970s are not joined in the southern part of EL 3169, as had been historically inferred. Instead, it now appeared that holes LN0031 to LN0034 had cross-cut the Lake Tinko paleochannel, whereas on line A, holes LN0025 to LN0027 and LN0038 to LN0040 had cross-cut the Lake Namba paleochannel. Drillholes LN0001 to LN0024 confirmed the presence of a newly defined paleochannel in the area to the east of the Lake Namba Palaeochannel, that Afmeco had originally inferred from Tempest and gravity data. The company named it the ‘Coolibah Paleochannel’. Ater completing its first drilling campaign, Afmeco reviewed the effectiveness of its primary geophysical exploration methods that had been used until then. On EL 3168 and across the northern part of EL 3167, most of the targeted TEMPEST AEM features are located in the upper part of the Tertiary sedimentary sequence, and correspond to clays and silts. Logged induction values showed that the highest conductive zones are located within or above the carbonate-rich horizon. Furthermore, within the carbonate-rich horizon itself, induction values strongly increased immediately below modern drainages (giving rise to the targeted channel-like features). This spatial relationship indicated to Afmeco that the higher induction subsurface zones that had been originally targeted using the AEM data may not necessarily be related to lithological variations, but may be related to salinity variations of the water table below modern drainages. The high induction values and strong AEM features recognised in the upper part of the profiles are in accordance with the groundwater properties of some water bores of the region, which display a reversed salinity profile, with saline water in the upper part of the Tertiary sequence and fresher water below. The shallow conductive features that result, and which dominate the CDI sections, would act as opaque 'screens' that preclude EM interpretation methods from seeing below them. On EL 3169, the targeted AEM features do reflect actual sand-filled paleochannels. Drillhole LN0001 was established as a water supply bore for the 2006 drilling campaign, and sampling its discharged groundwater that came from a basal sand aquifer between 72 and 84 m depth gave salinity values of 39,000 ppm. This evidence of a ‘normal’ salinity profile, and the small thickness of the clay cover, were believed to be the main reasons why the TEMPEST survey method was successful in this area. The success of ground gravity surveying to identify paleochannels on EL 3169 Afmeco thought could be explained by the strong density contrast between the Tertiary sediments and the Proterozoic crystalline basement rocks into which the sand-filled palaeochannels are incised. On EL 3167, only one hole intersected a palaeochannel, but it is located where there was no ground gravity survey data. On EL 3168, a correlation was found between sand thickness and residual gravity lows, but further drilling was needed to confirm this relationship. Afmeco concluded that it is probably more difficult to identify paleochannels on ELs 3167 and 3168 than on EL 3169 using ground gravity surveys, because of the low density contrast between Tertiary sediments and underlying Cretaceous or Cambrian sedimentary formations.