A drilling programme has been carried out under tenure of a mineral exploration licence by the PEL 6 Patchawarra Farm-out Block partners, to investigate the origin of a 400 API unit radioactivity gamma-ray log kick noticed to occur at 47.12 m below ground surface in the oil exploration well Moorari 2. During the period March-October 1975, 26 vertical open rotary / partially cored drillholes totalling 1863.55 m of penetration (including 18.21 m of cores cut in holes ST5, ST5A and ST26) were completed in close proximity to Moorari 2, and also on a 500 m x 1.5 km grid within an area extending up to 5 km south-west of this well, to characterise the Recent to Tertiary strata containing the anomaly, and to look for an inferred upper Tertiary palaeochannel structure. Results were somewhat inconclusive, but in general have downgraded the potential for finding uranium in the Tertiary sediments present within EL 138. The drilling revealed a non-marine clastic sequence of interbedded argillaceous and arenaceous sediments of probable Quaternary to upper Tertiary age, which was arbitrarily subdivided into 9 units. The lowermost two units, haematite-rich shale/sandstone overlying a carbonaceous shale, imply the existence of a redox environment suitable for the entrapment of secondary uranium mineralisation. The Unit 8 facies appears to be the host for the Moorari 2 gamma log anomaly source, however, no significant uranium or thorium assay values were returned from XRF analysis of 62 samples taken in this unit (U is mostly < 4 ppm, Th is mostly 100 counts per minute that were obtained in 5 drillholes positioned next to Moorari 2, and the explanation may be that a disequilibrium situation applies here, with respect to uranium daughter products. An isolated occurrence of a probable palaeochannel fill sand body was encountered in drillhole ST17, where an oxidised, fine to very coarse unsolidated sand interval almost 30 m thick was intersected. Continuity of this sand downdip to the south-west, and of the target, some distance removed anomalous gamma ray zone, could not be demonstrated by interpretation of the subsurface data, nor was a source for the radiation able to be identified, despite the conduct of trace element analyses and petrographic and mineragraphic examinations on drill core samples. No content of volcanic ash could be seen in the radioactive core section. Porous sediments existing in a non-oxidising environment were also not found.