Annual report of Ngalia Basin Uranium JV activities for 1973.

Abstract

This report summarises all the work carried out by the Uranium Joint Venture during 1973. Although separate reports deal with facets of the 1973 effort, brief summaries of all pertinent results are embodied herein. Data not dealt with in separate reports is presented in more detail. This report includes sections on prospecting, geological mapping, exploration statistics, and a major section on the Rotary/ Percussion Programme, its assessnent and its relation to further work. A list of recommendations for the 1974 programme is also given. The highlight of this year's prospecting work was the discovery of the Bigryli Prospect where a series of discontinuous carnotite occurrences were detected over a 12.5 km. strike length. Another discovery in 1973 was Karin's Anomaly. Rotary/Percussion Drilling at the Walbiri Prospect commenced on August 10th 1973, and the contract was terminated on December 12, 1973. The drilling was hampered by unexpectedly hard ground, frequent unseasonal rainy conditions, and shortages of drill pipe and equipment. A total of 3500 metres of drilling was completed. The delay in the signing of the Operating Agreement until July reduced the effective time of available exploration by about 60% and caused the Operator major difficulties with the management of the programme. Carborne and ground radiometric prospecting continued during 1973 using BSG-IS scintillometers. An orientation survey was flown to assist in planning of a detailed airborne survey proposed for 1974 over the outcrop areas of the northern margin of the Ngalia Basin. Approximately 70 line kilometers of ground radiometric prospecting have been completed for the year over Mt. Eclipse Sandstone. Details of results for individual EL's are shown in the company report.

In addition to the traverses, a considerable amount of traversing was carried out in the Bigryli Prospect in order to rapidly determine the extent of newly discovered mineralization. This work, although predominantly within EL 605, extended into EL 359. Statistical analysis was carried out on 1492 radiometric readings over part of the B-sandstone at the Walbiri Prospect. A cumulative frequency' plot clearly identifies two populations, one with a median of 35 and standard deviation of 11.5 and one with a median of 51 cps and standard deviation of 15 cps. An inspection of the map suggests that population A represents unmineralized ground and B mineralized, as all mineralized areas occur within the 50 cps contour. If median plus 3 standard deviations is accepted as a reasonable test, of anomalism then all readings above 70 cps in Mt. Eclipse Sandstone should result in more detailed examination of the area and any reading above 105 cps should be thoroughly prospected in an attempt to discover higher grade material. The discovery of the Bigryli Prospect was made as a result of regional ground radiometric prospecting aimed at eventually covering all Mt Eclipse Sandstone outcrops with traverses spaced 0.5 kilometers apart. Some detailed ground radiometric work was commenced at Bigryli, in order to outline mineralization prior to drilling in 1974. Detailed ground' radiometric work at the Walbiri Prospect was continued. Results for 1972 and 1973 are included in this report. It is possible to relate all surface mineralization to drill hole intersections and the converse is true. The correlation between surface and down dip mineralization was already apparent in 1972, but was further supported by the 1973 drilling results. Detailed ground radiometric work failed to locate any surface expression of Karin's Anomaly (carnotite in seismic shot hole cuttings), but some anomalous radioactivity was detected in nearby Mt Eclipse Sandstone outcrops. A detailed radiometric survey together with geological mapping outlined the limited extent mineralization at the Coonega Prospect. A total of 693 line kilometers of carborne radiometric traversing has been completed during the year. Use was made of station and seismic tracks whenever possible. In the latter case, seismic shot hole cuttings were checked radiometrically. Although no radiometric anomalies were found by carbonic prospecting in 1973, Karin's Anomaly was discovered during the course of this work. The discovery of Bigryli Prospect accentuated the desirability of rapidly prospecting all remaining unchecked Mt Eclipse Sandstone outcrop areas. The narrow elongated shape of the mineralized zones at Bigryli combined with topographic factors make it a difficult target for airborne spectrometry. The orientation survey aimed at providing basic data to enable planning of an effective airborne survey for 1974. Six hours of flying time were utilized in 1973 during which 311 line kilometers were flown. The survey was flown on the 15th December by Aero-Service (Aust) Pty Ltd. Thirty-six test lines totaling 311 kilometers in length, were flown.

The aircraft was a Twin Pioneer with an operating speed of 85 knots. Due to very strong wind during the survey ground speeds were very variable and up to 140 knots flight elevations varied from 80 metres to 175 metres. Navigation was visual recorded by 35 mm continuous tracking film. Spectral windows of

1.367 to 1.56 Met. (K), 1.66 to 1.86 14ev. (u), 2.22 to 2.72 Mev. (Th) and 0.8 to 3.8 14ev (Total Gaunt) were used. Data was recorded on: Six channel Brush chart recording the four the radiometric channels, radar elevation and 2 gamma magnetics. The radiometric channels were corrected for Compton scattering assuming a planar source, deviation, and the 2000 ft elevation background was suppressed. Uranium and Potassium channels on an extended 10 in chart. Magnetic tape record of all raw data and digital printout of all raw data. All known mineralization at Bigryli was easily detected on lines passing within 100 metres laterally at elevations of 90 to 130 metres. As a result of this survey, an airborne survey at 100 metre elevation and 500 metre line separation was recommended for the outcropping Mt Eclipse area April 1974.