Annual Report EL 1321 Ngalia Basin.

Abstract

Due to lack of available ground covering extensions to known mineralization, the exploration licence was applied for to allow a drilling programme to test for mineralization potential in the upper units of the Succession. The granitic terrain to the north of the Ngalia Basin apparently was the provenance for the sediments that now comprise the (?)Carboniferous Mount Eclipse Sandstone. The granites appear to have an above average Uranium content with 5 - 20 ppm U being common (values of 30 ppm and 60 ppm are known from the Napperby sheet area, and similar values can be expected to the north of the N'Galia Basin in this area). The Uranium within the granite is in a form that allows it to be mobilized, by groundwater action, along existing fractures. This is exemplified by the Dingo's Rest South area. The Uranium can also be mobilized by the chemical action of present day rainwater as Quaternary outwash areas draining the granites show a high radiometric background. Within the Mount Eclipse Sandstone, suitable physical traps (in the form of fractures or as porous horizons) must exist. The Bigrlyi Prospect mineralization occurs in such zones close to the local base of the Mount Eclipse Sandstone. The mineralization occurs in what is termed the 'Bleached Zone' a light biscuit red coloured medium to coarse grained quartz sandstone with minor carbonaceous matter that appears to be discordant to bedding. In the most important area of mineralization at Bigrlyi the 'Bleached Zone', containing disseminated carnotite and uraninite, occurs above a calcite cemented level that may have acted as a chemical barrier to the migration of the uraniferous waters percolating through the area. Thus both suitable physical and chemical traps exist in the area. At present the only mineralized 'Bleached Zone' recoflized in the immediate proximity to EL 1321 is that at the Bigrlyi Prospect. The drilling programme was designed to locate other such bleached and mineralized zones in the upper levels of the Mount Eclipse Sandstone. Starting from the northern edge of the N'Galia Basin, a measured traverse was done over outcropping basin sediments within E,L. 605, and this was continued through E.L. 1321 as a drill traverse. The objectives of this programme were: 2.2.1 to obtain a geological section through the complete local sequence of the basin, 2.2.2 to test for mineralization potential. A locally weakly anomalous 'Bleached Zone' out crop on both limbs of the Patmungala Syncline. Drillholes, located at the outcropping margins of the Patmungala Syncline, were planned to test this zone, 2.2.3 to obtain stratigraphic and structural data on the Patmungala Syncline. A series of five 200-300 metres holes was planned to span the Patmungala Synclirte to provide information on the upper part of the sequence in the Patmungala Syncline.