Legacy product - no abstract available

Legacy product - no abstract available

Legacy product - no abstract available

These documents have been scanned by the GA Library. Please refer to the document for contents.

These documents have been scanned by the GA Library. Please refer to the document for contents.

These documents have been scanned by the GA Library. Please refer to the document for contents.

These documents have been scanned by the GA Library. Please refer to the document for contents.

Beach sand deposits along the Australian east coast (Gardner, 1951 a, b) have yielded a large part of the world supply of zircon and rutile since the year 1936. During 1953 the returns from the export of these minerals amounted to more than £2,000,000. In addition the black sands contain a small proportion of monazite, which is a source of cerium and of thorium, a fissionable element that may be used for the generation of atomic power. From a comparatively small beginning the mid-1930's the beach-sand industry grew rapidly during the war and early post-war years. Little was known of the distribution and reserves of the deposits; hence the Bureau of :Mineral Resources undertook a detailed investigation of the coastal area between Southport, Queensland, and Woody Head a little north of the mouth of the Clarence River, New South Wales. The primary object of the survey was to determine the reserves of monazite and therefore of thorium; the reserves of zircon, rutile, and ilmenite were also determined. In this report the source rocks of the sand and heavy minerals are considered in a brief outline of the physiography and general geology of the country between the coast and the main divide. The deposits are described and their origin and distribution discussed in connexion with late Pleistocene and recent changes, in sea level. The reserves and distribution of the heavy minerals arc broadly summarised, and more details of reserves and dimensions of deposits and overburden are given in descriptions of the individual areas.

At the request of the Geological Survey of Western Australia, the Bureau of Mineral Resources, Geology and Geophysics provided geophysical staff and equipment to assist in the search for underground water supplies in certain areas of Western Australia where additional supplies are required for further development of the farming 'industry. The main objects of the survey were to test several -types of resistivity equipment and to determine their limitations and optimum working conditions, to estimate the accuracy of depth determinations to formation discontinuities, to determine, the nature of the discontinuities, and to estimate the degree of salinity of the ground water. Results show that in 75 per cent of the measurements made, errors in depth determinations were within ± 20 per cent. Although limited control data were available, it was often possible to recognize limestones, cementation zones in limestone, sands and ground-water levels, and in granite areas, the transition from weathered to fresh granite was readily recognized. Where conditions were favourable, a satisfactory correlation was obtained between resistivity values and the salt content of solutions in a formation, provided the porosity of the formation was known. Although the main object of the survey was not, the finding of new underground water supplies, this WJ.S one of the aims in the Cue area, and a location was found where conditions for a large supply of good-quality water appeared to be favourable. The resistivity meter which was used in the tests was developed by the Bureau of Mineral Resources, and operated very satisfactorily. The Megger earth tester was reliable up to electrode spacings of 100 feet. The value of future test surveys for underground water would be greatly enhanced if more comprehensive bore information were available for correlation and combination with geophysical and geological observations. Such information should include the porosity and permeability of formations, screen analyses of samples, and salt content and resistivity of bore water.

Legacy product - no abstract available