Legacy product - no abstract available

Rurnbalara railway siding is 831 miles by rail north of Adelaide, South Australia, and 120 miles by rail south of Alice Springs, Northern Territory. The ochre deposits (Plate 1) are situated in desert country, 15-20 miles northeast of the siding. No permanent water supply has been developed in the vicinity of the mines. Numerous mesas in the district are capped by siliceous laterite (grey billy), and are composed of approximately 150 feet of horizontally-bedded, leached shales and sandstone containing numerous fossils of Lower Cretaceous age. These beds, for which the name Rumbalara Shale is proposed, rest unconformably on the eroded surface of flat-lying, current-bedded sandstones of which the age has not been determined; it is proposed that the sandstone beds be called the De Souza Sandstone. .The ochre occurs in beds 1 to 4 feet thick; the best grade consists of soft, friable, golden-yellow material, free from grit and with good paint-making properties. Throughout the deposits the ochre occurs at the same stratigraphic horizon- at the base of the Lower Cretaceous-and appears to be of sedimentary origin. Excluding 1943 and 1944, annual production during 1940-1948 averaged 500 tons; in 1943 and 1944 production was 1,345 and 1,439 tons respectively. The deposits are very extensive, but prospecting carried out to date indicates that only some of them contain ochre equal in grade to that being mined. However, although there are virtually no proved reserves, the field is probably capable of supplying Australia's requirements of yellow ochre for many years.

Legacy product - no abstract available

This map has been prepared to display the probable form of the Isogonic Lines in the regions surrounding Australia, the boundaries being the meridians 85°E and 180°, and the parallels of latitude 10°N and 60°S. This report contains explanatory notes to the isogonic map.

A geophysical survey was made in the Rum Jungle district in October and November, 1950, using self-potential and potential-ratio methods. This investigation formed part of a larger programme of geological and geophysical exploration for uranium minerals. Self-potential surveys were made over three areas, namely, Brown's Copper Mine Area, Intermediate Area, and White's Area. A potential-ratio survey was made over only the first of these. This report gives an account of the geophysical work conducted in each of these areas. The results of the survey are described, and recommendations for future drilling work are given, for each of the surveyed areas respectively.

The material described in this report was collected and forwarded for examination by Mr. M.R. Banks of the Geology Department, University of Tasmania. The report comprises notes on the lithology, fossil content, state of preservation, and correlation, of the samples.

This report is comprised of nine separate sub-reports, referred to as records nos. 1951/3a to 1951/3i. Micropalaeontological examinations were conducted on samples from various localities in the region of Mt. Gambier, South Australia. The results of these examinations, together with any accompanying notes, are recorded in the respective reports.

At the invitation of Prof. S.W. Carey, the author visited Tasmania during the period 15th November to 2nd December, 1950, to take part in discussions on Cambrian geology in Tasmania and to learn in the field the results of recent investigations on Tasmanian older Palaeozoic rocks. During the visit the author had the opportunity of expressing his opinions both on newly discovered fossils and on the age of some Palaeozoic units, and the main object of this report is to record these opinions.

Nine samples of clays from Western Australia were received from R.S. Matheson for micropalaeontological examination. No microfossils were found in these clays. A description of these samples is given in this report.

Towards the end of 1950, the deep bore which the Shell Development Company was drilling to test for oil on the Morella structure, 35 miles south of Rolleston, entered andesite at approximately 4000 ft. After boring about 200 ft into the andesite, the Company decided to abandon the hole. A new site for a test bore was selected on the Comet anticlinal structure, 60 miles north of Rolleston. Before proceeding with this new test, evidence was needed to ensure that neither a shallow basement nor volcanic rocks existed under this structure. The Bureau was therefore asked to shoot a refraction traverse over the anticline, in order to determine if basement rocks were likely to be present at a shallow depth. As a result the Bureau sent a seismic party to the area during January 1951. Fairly definite evidence was obtained of basement velocities occurring at a depth of less than 3000 ft, and after discussions, a decision was made not to proceed with the drilling of the Comet structure. The results have now been investigated in detail and are presented in this report.