Final report on exploration activities EL 1389 Tennant Creek, Northern Territory

Abstract

Work undertaken on EL 1389 by MPAL has included evaluation of available aeromagnetic spectrometer data, a photogeological study, geological mapping, lithogeochemical sampling and percussion drilling. A combined airborne spectrometer and magnetometer survey was flown over the Tennant Creek area in 1977-78 by Geometries Inc on behalf of AOM. A detailed evaluation of the geophysical data was then undertaken on behalf of MPAL by Loxton, Hunting and Associates of Canberra. In late 1978 Marathon Petroleum Australia Ltd commissioned Loxton, Hunting and Associates to undertake a photogeological study of part of the Tennant Creek area. This study included the area granted as EL 1389. The aim of the study was to provide a detailed structural and lithological map on which exploration could be based. A field check of the photogeological study was made in October 1978. Within the licence area a very pronounced magnetic boundary was interpreted along the southern margin of the area correlating in part to the photogeologicaI boundary between greywacke and shale. A highly magnetic anomaly in the extreme north-east of the licence area warranted further investigation. An area B3 is, marked by a very low amplitude magnetic anomaly lying close to a fault intersection. Area B4 is similar with an additional slight uranium response. Areas of higher uranium background were delineated in the volcanics, granites and greywackes. These potential target areas had been selected which warrant further investigations. A number .of major faults were interpreted from the geophysical data. The basis of the 1979 field programme was a rock chip geochemical sampling programme over the selected rock types in the Tennant Creek licence areas. The main lithotype sampled was ironstone however volcanics and arenaceous and pelitic sediments were also assayed for trace element contents. The sampling programme covered EL 1389 and was aimed at expanding on the work undertaken in 1961 by Macmillan and Debnam and to identify indicator elements that may be useful in defining potential drilling targets. During October - November 1979 Rockdril Contractors Pty Ltd of Brisbane supplied a truck mounted Foxmobile drilling rig to carry out a forty five hole percussion drilling programme. Six profiles, A, B, D, E, H, U, were drilled to test various anomalies. During 1980 a sedimentologicaI reconnaissance study was undertaken and included EL 1389. A soil sampling programme was conducted over EL 1389/A on a grid established in mid-1980 as an enlargement of Drill Profile B. A base of slope sampling programme was also conducted with the aim of attempting to define areas of similar geochemical erivironments which could help in future exploration planning. Two areas within the licence were tested with open hole rotary percussion drilling. Rockdril Contractors Pty Ltd of Brisbane provided a Schramm 685 to undertake the programme. A total of 14 holes (total 620 metres) were drilled in EL 1389/A to, better define and test geochemical anomalies indicated in the holes drilled in 1979. During 1981 geological mapping was undertaken in both EL 1389/A and EL 1389/B with the aim of determining the relationships between the Bernborough and Carraman Formations and to collect trace element data from the volcanics. A four hole rotary, percussion programme was undertaken in EL 1389/A. One profile of 3 holes (aggregate 64 metres) was drilled to test the relationship between Bernborough and Carraman Formation while the fourth hole (totel 103 metres) was drilled to obtain stratigraphic and geochemical data. Details of all phases of the exploration undertaken by Australian Ores and Minerals Ltd and Marathon Petroleum Australia Ltd are available upon request from the company offices in Perth and Brisbane respectively or from the files of the NTDME in Darwin (see attached list of.references).