HomeWelcomeUpdatesCompanyAircraftPeopleProjectsEquipmentOperationsPhoto AlbumGuest BookSearchAdastrianaQuestions

Lyell - E.Z. Explorations - Tasmania 1957



The Modern Way

Throughout the world, the search for new mineral deposits has been greatly intensified in recent years and new techniques are being employed.

Our own company in conjunction with other mining companies is actively engaged in such work in various parts of Tasmania.

This article describes the activities of Lyell- E.Z.-Explorations, the organisation formed by the Mt. Lyell Mining and Railway Company Ltd., and the E.Z. Company to explore for mineral deposits within an area of several thousand square miles in South Western Tasmania.

The exploration resources of both companies have been pooled in order to provide the technical staff and equipment necessary for this major project. Work is being directed by a Committee consisting of officials from both companies. For reasons of proximity, Queenstown is the base for most operations.

The area is one of the most inaccessible in Australia and apart from a few families and an occasional survey party, the area is uninhabited. There are no roads and few foot tracks. A series of high rugged mountains protect the eastern side and the dense rain forests of the Gordon River effectively block access from the north. On the south west side the precipitous shores and occasional beaches are pounded by the rough seas of the Southern Ocean. The records of early exploration tell of slow progress and of difficulties encountered.

For these reasons the existing maps based on scanty and incomplete data are not wholly reliable. The main problems to be overcome were therefore those of speedy access and suitable maps.

The problem of access was solved by contracting for the use of the A.N.A. Bristol Sycamore Helicopter "Yarrana" (VH-INO Ed) and the problem of maps by contracting for Adastra Hunting Geophysics Pty. Ltd., to make a series of aerial photographs of the whole area from an elevation of 18,500 ft.

During the last summer season, the helicopter was used to fly three man field parties and their equipment to more than thirty places up to 80 miles from Queenstown for geological reconnaissance. Field parties usually reached their destination in 30 to 40 minutes and were fully effective on arrival. The corresponding journey on foot with limited equipment would have taken at least as many hours. The field parties usually remained in the field for two weeks and each party was in radio contact with Queenstown. The use of bushmen with local knowledge has assisted the work. All parties were kept supplied with stores and other needs and a total of 500 passenger flights was made and 80 tons of material were transported.

The aerial photographs each 9" x 9" square depicting 11 square miles of country proved to be ideal for recording of observations and for locating places of interest. They faithfully portrayed details of all ground features and enabled an experienced geologist with the use of a stereoscope to interpret the geology of the rock formations in the country surrounding the area which he had visited, and thus build up a geological map of the whole region. This information is being depicted on a large base map, made by joining up a series of aerial photographs to make what is called a "mosaic".

By these means, data were obtained in a few months which by any other method would have taken several years. At the present time it is still being assembled.

The interpretation of the information obtained will be assisted by geophysical surveys. Aircraft of the Adastra Company carrying sensitive recording instruments are being flown over the area (covering several hundred square miles per day when weather permits) at a height of 500 feet above the surface and at a fixed spacing to measure the magnetic, radioactive, and electrically conductive properties of the rocks below the aircraft. Ore bearing formations often exhibit a higher degree of conductivity or of magnetism than unmineralised formations, and these places may show up on the graphs produced by the instruments as peaks or "anomalies" on an otherwise straight line.

The aircraft takes a continuous series of 35 mm. vertical photographs which allow its course to be plotted upon the mosaic. The camera is synchronised with the other instruments and this enables the position of the anomaly to be identified. From the responses so obtained, in conjunction with geological data it will be possible to select a number of areas for more extensive investigation on the ground by geological, geophysical and geochemical methods. The technique of geochemistry is being used to test soil samples and stream waters for minute traces of metals to determine possible areas of concentration which could indicate the presence of an ore body.

Thus by a process of elimination the most likely ore bearing areas are selected and the amount of rough country in which survey and access lines have to be cut, is reduced to a minimum.

It is hoped that by thus directing the modern prospector to the most likely areas, the work will ultimately lead to the discovery of worthwhile mineral deposits.

This more intensive work will be accelerated during this Summer using A.N.A.'s Djinn helicopter (VH-INP Ed).

E.Z. Review December 1957, Volume 1 No. 9
Published by Electrolytic Zinc Company of Australasia Ltd.

(Photographs have been omitted.)

Thanks to Doug Morrison for sourcing this article.