This Bulletin describes magnetic surveys of the Savage River and Long Plains iron deposits in northwest Tasmania made by the Bureau of Mineral Resources, Geology and Geophysics between 1957 and 1962. The results of the surveys are shown as vertical magnetic field contours. The Bulletin includes a discussion of the theoretical magnetic anomaly due to an infinitely long dipping vein of infinite depth extent, and gives an interpretation for the magnetic anomalies observed on a selection of traverses. The drilling completed at Savage River and Long Plains as at May 1964 is summarised and compared with magnetic profiles. Recommendations for additional drilling are made, particularly in areas where drilling has not been done.

This Bulletin presents the results of a marine geological survey carried out by BMR in the Arafura Sea in 1969 as part of a program of regional geological reconnaissance mapping of the Australian continental shelf. It is a continuation of work in the Timor Sea and northwest shelf (van Andel, Veevers, 1967; Jones, 1968, 1970). The area surveyed is the northern Australian continental shelf between longitudes 130° and 136°E and between latitudes 8° and 12°S (Fig. 1), an area of about 240 000 km-. From 2 to 25 May the Japanese research submersible Yomiuri and its mothership, the converted deepsea tug Yamato, were made available. The major part of the survey lasted from 21 September to 6 December 1969, using the chartered oil-rig supply vessel San Pedro Sound as a platform.

Following the discovery of large phosphate deposits in the eastern part of the Georgina Basin in 1966 by Broken Hill South Limited, the Bureau of Mineral Resources embarked on a detailed stratigraphical and palaeontological study of the Cambrian sediments of the area in 1967. Particular attention was given to the phosphatic part of the section, but new information on the associated Cambrian units was also gained. In 1967, F. de Keyser, J. H. Shergold, C. G. Gatehouse, R. Thieme, and C. Murray (Geological Survey of Queensland) mapped the Burke River Outlier, and in 1968 de Keyser and Thieme mapped the Cambrian of the northeastern corner of the Barkly Tableland. In 1969 de Keyser and P. J. Cook completed the mapping of the known phosphogenic areas in Queensland when they mapped the eastern margin of the Georgina Basin in the Mount Isa/Urandangi area. Associated palaeontological, petrological, and geochemical studies were also carried out.

A collection of palaeontological papers 1972 (bulletin 150)

The Stairway Sandstone was studied in the field in 1962 and 1963 during the reconnaissance geological mapping of the Amadeus Basin. In 1964 rather more detailed work was carried out: sections were measured and cross-bedding determined throughout the Amadeus Basin, and the phosphorites were examined in some detail because of their possible economic significance. In 1965 and 1966 surface and subsurface material was studied in detail to determine the provenance, environment of deposition, and palaeography of the formation. This work was done partly in the laboratories of the Bureau of Mineral Resources, and partly in the Department of Geology of the Australian National University, Canberra (under the sponsorship of the Bureau of Mineral Resources).

Conodonts of Ludlovian-Gedinnian age from the Yass Basin of New South Wales are described. The fauna consists of 61 species referable to 24 genera of which one, Coryssognathus, is new. Four conodont assemblage zones are recognized and correlated with classic Ludlovian-Gedinnian zones of Europe; two faunas, one of probable latialatus Zone age and the other of probable woschmidti Zone age, have also been recovered. Reworked Ludlovian conodonts from Devonian conglomerates at the top of the Yass succession are also described.

The northern fall of the Central Range, the largest unexplored area in New Guinea (Fig. 1), separates the swampy Sepik Plain in the north from the high dissected plateau forming the backbone of New Guinea to the south. The whole region is rugged and covered by tropical rain forest; it is almost uninhabited, and as there are few tracks, the long meandering southern tributaries of the Sepik River provide the only practicable access. The South Sepik region occupies a small segment of the fundamental break separating the stable Australian continental block from the oceanic crust to the north. This break, which is marked in the South Sepik region by the Lagaip Fault Zone, has had a profound effect on sedimentation in the region throughout the geological record: shelf-type sediments were laid down on the continental block, while geosynclinal sediments were being deposited to the north. The oldest rocks are Middle and Upper Triassic in age and include a widespread and distinctive volcanic unit called the Kana Volcanics. They are succeeded unconformably by a thick sequence of black pyritic shale (Lagaip Beds), which was laid down south of the Lagaip Fault Zone during the Jurassic and Cretaceous.

This report presents the results of geochemical investigations in the Mount Isa district, northwest Queensland. Samples, mainly from cores, represent Group 2 Shales (comprising Kennedy Siltstone and Spear Siltstone), Urquhart Shale, Native Bee Siltstone, greenstones, and local basic igneous rocks. These have been used to study element distributions in mineralized and unmineralized localities. It was found that primary element dispersions are associated with the 1100 Cu orebody, but not with the Ag-Pb-Zn bodies. This, together with the different modes of occurrence of the orebodies, suggests that the mineralization at Mount Isa took place in two separate events. The Ag-Pb-Zn deposits are considered to be syngenetic whereas the Cu deposits appear to be, in part at least, epigenetic. The chemical evidence suggests strongly that much of the Cu in the silica dolomite bodies was derived from the underlying greenstones. In addition, an attempt has been made to differentiate the Urquhart Shale from the other units on the basis of chemical composition. Of the elements analysed, Ca appears to be the most diagnostic and it may be possible to define the upper limit of the Urquhart Shale using this element.

Collection of Palaeontological Papers, 1983.

The Upper Devonian to Lower Carboniferous Drummond Basin sequence crops out over an area of approximately 25 000 km2 , mainly west but also east of the Anakie Inlier in east-central Queensland. The Drummond Basin is a structural remnant of a large intermontane depositional basin that developed in the Tasman Geosynclinal zone after the Tabberabberan Orogeny. It received up to 12 000 m of predominantly fluviatile sediments which were transported into the basin by a northerly flowing river system. There may have been some marine incursions. Basement to the basin consists of early Palaeozoic slightly metamorphosed sediments and granite. Sedimentation in the Drummond Basin ceased at the onset of the Kanimblan orogenic event, during which the sequence was folded and uplifted to form a structural high shedding detrital material into the Bowen and Galilee Basins.