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  • This report is based on the microexamination of samples from 13 bores and one surface sample from the Muswellbrook area received from M.A. Reynolds. A detailed description of the microfaunal content of the samples is given below.

  • The London Bridge Limestone has been traced along its strike from a point five miles south-south-east of Queanbeyan to a point three miles south-east of Bredbo, a distance of forty miles. At London Bridge this formation attains its greatest development and a large-scale geological map of this area has been prepared. Fossil collections have been made from localities along this formation and the fauna has been examined. A description of the coral Pycnostylus ? sp. nov. is given. The stratigraphical position of this formation has been placed within the Wenlock Epoch, possibly within the Lower Wenlock.

  • Manganese deposits in the Gregory Range, Western Australia were examined and mapped by officers of the Geological Survey of Western Australia and the Bureau of Mineral Resources jointly. The investigation indicated the presence of 93,000 tons of manganese ore distributed between 37 separate bodies contained in 13 groups. Numerous small bodies each containing less than 200 tons of ore have not been included in the tonnage estimate. The grade determined by chip sampling the surfaces of the outcrops is generally high. The range of composition of samples is: [see table in record]. The deposits occur as replacements of silicified bands in dolomitic limestone and as fillings of irregular cavities in the limestone. A few thin deposits in the south-eastern sector of the field overlie quartzose rocks.

  • Bore No. 8287, Mr. E.J. Riches, "Myrnong", Bourke - Thirteen samples were submitted for examination from this bore. A detailed examination of these is given below. Bore No. 4676, P. Mallon, "Avoca", Bourke - Fourteen samples were submitted from this bore and a detailed examination of them is as follows.

  • This report deals with a triangular area of pre-cambrian meta-sediments, totalling about six square miles in which occur copper-uranium orebodies of the Rum Jungle area. The area is situated 55 miles south-south-east of Darwin, Northern Territory. Plane table mapping of [a] portion of the area was carried out by N.J. Mackay and D.J. Gates in 1950 and the area mapped was extended by E.K. Carter in 1951 to cover the whole of the embayment area. The meta-sediments of the area form a large dragfold in the north side of the N 60°E striking Giant's Reef fault, along which there is a horizontal displacement of 3.25 miles. About 5,000 feet of varied meta-sediments are present. The carbonaceous slates are the host rocks for mineralization. Granite and granitized sediments lie to the north, east and south of the area and they occupy the core of a domal structure in the meta-sediments. Three periods or phases of faulting are recognised, the first is the post-granite Giant's Reef faulting, which produced the major dragfold, the copper-uranium mineralization may have been associated with this period of faulting. The second is an axial plane shearing of the dragfold, which is post-mineralization in age. The third system of faults consists of a large number of cross-faults which strike from N 60°W to N 30°E and which have displaced the granite margins, Giant's Reef fault and the axial plane shear. The known copper-uranium mineralization is confined to the axial region of the dragfold and is found almost entirely in carbonaceous slates. The most favourable area for further prospecting appears to be under the deep soil along the axial plane zone, east-north-east of Dyson's Prospect.

  • Wave Hill Station, a cattle station in the north-western portion of the Northern Territory, is situated between the 15 in. and 20 in. isohyets of annual rainfall. This Station has a large area of grassland on volcanic downs which cannot be fully utilised because of the lack of surface waters: supplies of underground water are essential for the expansion of the pastoral industry in this area. Bore records up to 1949 show that at least 30 bores have been sunk of which more than half are useless and only a very few produce a sufficient yield.

  • The Frazer radioactive prospect was located by the Geophysical Section of the Bureau of Mineral Resources during Airborne Scintillometer and magnetometer surveys carried out during 1952 in a Dakota, VH-BUR, over country surrounding Rum Jungle. Radiometric Investigations showed that the radioactivity is confined to the ferruginous surface rocks which may represent a lateritic deposit. To the east of the costean occur a few low ridges comprising a hematite quartz quartzite breccia and a white quartz breccia. The hematite quartz quartzite breccia appears to overlie the white siliceous breccia. The ferruginous breccia exhibits some radioactivity and this may explain the occurrence of the radioactive laterite. No radioactive mineral can be defined.

  • The stratigraphy and structure of an area in the Carnarvon sedimentary basin covered by the Williambury and Moogooree one mile sheets, is described. Resting unconformably on a Pre-Cambrian basement of schists gneisses and granites, are Devonian marine sediments 4750 feet thick, followed conformably by Carboniferous approximately 2150 feet thick; these are separated from the overlying Permian more than 8000 feet thick, by a possible hiatus. The Cretaceous System is represented by about 40 feet of siltstone lying unconformably on the Palaeozoic rocks. Marine Tertiary arenaceous deposits are widespread and have a maximum thickness of 80 feet; they are not seen in contact with the Cretaceous rocks. The whole area has been subjected, in Tertiary time, to lateritisation, the most prominent feature of which is the presence of a silicified cap ranging in thickness from a few feet to 30 feet. In one place a post-laterite deposit of 12 feet of probably fresh-water limestone has been observed. An account is given of the structural geology, geological history, and physiography of the region.

  • A reconnaissance survey of the eastern half of the Canberra 4-mile sheet was made during the period January - February 1952. The area mapped may be arbitrarily divided into two sections: the western section includes the eastern halves of the Canberra, Michelago, and Bredbo 1-mile sheets, and the eastern section comprises four 1-mile sheets - Lake Bathurst, Braidwood, Araluen and Bendethera. Belts of strongly folded Ordovician, Silurian and Devonian strata, with associated elongate masses of granite rocks, were encountered; they trend gradually northwards. Graptolites collected from Ordovician strata provide means to date these rocks accurately, and further study of the corals collected from Silurian limestones will similarly permit precise dating. Three fossil localities were found in the Devonian strata, but the brachiopods collected, although well-preserved and representative of many genera, do not permit precise stratigraphical placing without more intensive examination. Outcrops are generally very good in all parts except the Lake Bathurst area, where an extensive cover of Tertiary and later deposits obscures the Palaeozoic rocks.