Annual report on exploration fo EL 1450 NW Simpson

Abstract

The Licence areas were granted on August 8, 1979. ELs l450 (N Simpson) and 1451 (Todd River) are situated in the Hale River and are considered to be parts for a variety of types of uranium mineralisation, including roll front and Alligator Rivers. No anomalies were recorded in the course of an airborne spectrometer traverse over the Licence areas and a different exploration approach involving a variety of alpha monitoring techniques including track-etch and gamma logging of accessible bores was adopted for target areas underlain bf sandstone units of the Amadeus Basin sequence. The Licence areas are underlain by younger Precambrian and Phanerozoic formations of the Amadeus basin sequence. The underlying basement rocks of the Arunta Complex outcrop along the eastern margin of the NW Simpson Licence area (EL 1450). The main units of the Amadeus Basin sequence outcroppings in the EL 1450 area are the Proterozoic Heavitree Quartzite Sitter Springs Formation (sandstone dolomite and basic volcanics) Pertatataka Formation (siltstone and shale) the Cambrian Pertaoorrta Group (dolomite and siltstone), the Silurian to Pevontan Mereenie Sandstone and the Devonian Carboniferous Sandstone and Brewer Conglomerate. Structurally EL 1450 consists of 2 synclinal basins, a basin of Proterozoic formations situated in the northern part of EL 1450 and a basin of Palaeozoic formations outcropping to the south. The only unit outcropping in EL 1451 is the Brewer Conglomerate which is apparently flat-lying in this area. Cenozoic cover rocks (ELs 1450 and 1451) consist predominately of Quaternary aeolian and alluvial sand. Work consisted of a limited helicopter mounted spectrometer survey of the outcropping Brewer Conglomerate Formation with the object of locating discrete uranium targets. No indications or uranium mineralisation were obtained from the survey. Subsequent orientation work in the area south of Alice Springs has established that the Brewer Conglomerate Formation consists of several differ ent facies and the poorly exposed sandstone facies represents the moat favour able environment for uranium mineralisation. Airborne spectrometer surveys are unlikely to be effective in locating uranium in the southern part of the licence area, which consists of sand covering various Palaeozoic formations, including the Brewer Conglomerate Formation. The technique has doubtful useful ness in the areas of outcropping Proterozoic and Palaeozoic formations. It is probable that any uranium originally present in the sandstone Units would have been oxidised and leached out of the near surface rocks. A different exploration approach was therefore adopted in evaluating target areas within Proterozoic and Palaeozoic formations, comprising the Amadeus Basin sequence, in the licence area. Gamma logging of accessible water bores and alpha monitoring of soil air,('Track Etch'), were the main techniques recommended.