Annual report for 1979 Litchfield uranium exploration joint venture summary

Abstract

The search for uranium deposits within Exploration Licences 1405, 1407 and 1408 is proceeding as a joint venture between A.O.G. Minerals and union Oil Development Corporation. Licences 1405 and 1408 were halved during the year, and the are available to the partnership is presently 971km2. Radiometric anomelies from the October 1978 airborne survey were identified by both A.O.G. and the survey contractor in early 1979, and 25 anomalies were selected for appraisal. Eight low intensity anomalies in EL 1408, and the only anomaly in EL 1405 were found to occur in permanent swamps, and these were not inspected. The remaining 16 anomalies were evaluated by grid traverses recording total radioactivity, uranium channel levels, ground magnetic intensity, Track-etch survey and soil geochemical values. A programme of 39 non-core drillholes, for a total of 1900 m was used to test the seven strongest radiometric anomalies and the known geochemical anomaly (in EL 1407), while 5 stratigraphic holes for a total of 190 m were drilled in EL 1405. Five of the six anomalies drilled in EL 1408 are south of the course of the Reynolds River, which is now identified as a major fault zone (south block downthrown). Holes in this southern block intersected unmetamorphosed carbonates and siltstones of the Daly River Group, with the base of this sequence. The remaining anomaly, at 'Palm Island', occurs in high grade gneisses, which can reasonably be correlated with similiar gneisses found further to the north in hole CSC 9 (1978 programme). Drilling in EL 1407 showed that the previously known geochemical anomaly is located in an area od massive granodiorite, and seven holes intersected marble and granulites at the Finniss Plains radiometric anomaly. All the holes were radiometrically probed, but no radio-activity higher than five times background was recorded. No base metal mineralisation was seen in any of the drillhole cuttings. Some minor analyses are in progress in samples from the Finniss Plains drillholes. The 1979 programme has eliminated all of EL 1405 and most of ELs 1407 and 1408 from further attention. The remaining areas of interest are the Finniss Palins region (EL 1407) with some lithologies reminiscent of the Golden Dyke Formation, and the band of fine grained graphitic and chloritic schists in the northeast corner id proposed in the 1980 dry season, using grid radiometrics (total count and uranium channel), magnetics and soil geochemistry. This stage is to be followed by a grid pattern of non-core holes, drilled to the base of weathering, from which a 'bedrock' geological, geochemical and radiometric map will be compiled.