EL 281, report on 1975 investigations

Abstract

Radiometric and radon anomalies in the Cooinda area are present over a geological succession believed to be equivalent to the host rocks at. the Ranger Deposits. Extensive auger and percussion drilling have not yet given any indication of economic uranium mineralisation close to surface. The anomalies are in part caused by superficial features such as laterite and organic material in swamps. Moving subterranean waters may influence radon measurements. Continued investigation of anomalies in this area is warranted because of the exceptionally favourable environment. But only a strictly limited percussion drilling programme can be recommended unless more promising results are obtained. Radiometric and geochemical anomalies at Anomaly 45 and the area just to the west are superficial and related to laterite development and weathering processes. Anomalies west of Anomaly 45 may be enhanced by the scavenging effect of manganese. They do not appear to have any economic significance. A Turam electro-magnetic survey at the West Jim Jim Breccia Prospect failed to indicate the presence of sulphides but it was affected by conductive overburden. Drilling will be required for a complete evaluation. Percussion drilling was carried out just west of the Exploration Licence boundary by the South Alligator Joint Venture at Anomaly 77. No significant uranium values were found down dip from anomalous results reported in the costeans excavated in 1974. No further work will be required.