EL 119 - Report on 1976 investigations.

Abstract

This report summarises exploration activities completed during the year in Exploration Licence No. 119, at Anomaly 3-171 which was protected by four Mineral Leases when the surrounding part of EL 119 was relinquished in December 1973, and within Mineral Leases held at Coronation Hill. The reduced Exploration Licence during 1976 comprised two separate areas totalling 57.5 square miles. It is located in the Mt. Evelyn district of the Northern Territory. In the Sleisbeck area a rotary percussion drilling programme of 8 holes totalling 574 metres investigated two Track Etch radon anomalies close to the escarpment forming the northern margin of an area of Middle Proterozoic sediments and volcanics. Six holes tested the Middle/Lower Proterozoic unconformity at a site where drilling in 1975 had indicated accumulation of uranium at the unconformity. The second anomaly, located over a thick succession of volcanics, had not been previously tested. Twenty nine Mineral Leases were pegged to protect possible extensions of known mineralisation at the old Sleisbeck workings. The area, now protected by leases at Sleisbeck, was mapped in detail in conjunction with a scintillometer survey. Three inclined diamond drill holes totalling 268 metres were completed at Anomaly 3-171. These investigated uranium mineralisation discovered in costeans during 1975. One hole intersected a steeply dipping fracture zone carrying values of 0.149% U3O8 over 3 metres between 50 and 53 metres down- the-hole depth. The north west margins of the Malone Creek Granite were mapped in detail in conjunction with a scintillometer survey in an effort to discover possible mineralisation of the type located at Anomaly 3-171. Sections of the Exploration Licence east of Coronation Hill and from Coronation Hill through to Pul Pul Hill were remapped on a reconnaissance basis in conjunction with scintillometer work. A total of twenty one new Mineral Leases were pegged in this general area. One inclined diamond drill hole was completed at 200.7 metres within Mineral Leases held at Coronation Hill. This was drilled from the north east slope below the old open cut to investigate gold values reported in volcanic rocks east of the open cut and to check for the possible extension of uranium mineralisation in favourable Lower Proterozoic rocks under the old workings. Only trace amounts of uranium were detected at the Middle/ Lower Proterozoic unconformity at Sleisbeck. The results are of academic interest and the area has been relinquished. The work at the Sleisbeck Leases indicated the possibility of uranium mineralisation occurring along the projected line of strike of the known occurrences particularly to the west. Further detailed investigations including core drilling are required at the old leases. The diamond drilling at Anomaly 3-171 indicated the presence of primary uranium mineralisation in steeply dipping fracture zones below the level of weathering. The width of ore grade material was disappointing but additional diamond drilling is required to test the ground adjacent to the intersection already obtained and to investigate similar occurrences in two other costeans. The work in the Malone Creek Granite area yielded no results comparable to those obtained at surface around Anomaly 3-171 and the area has been relinquished. The mapping and radiometric surveying carried out around Coronation Hill and Pul Pul Hill emphasised the need for more detailed geological work in conjunction with geochemical and radon surveys prior to any further drilling. Gold and uranium values obtained in core drilling at - Coronation Hill are not economically significant. They do require to be assessed in a regional context and at least one deeper hole at Coronation Hill should be drilled in order to penetrate the Lower Proterozoic succession. This might better be delayed until further detailed mapping in the general area has been completed.