No abstract available

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).

G50/B1-99 Vertical scale: 750

H51-B1/2339 Contour interval: 25

G50/B1-2247 Contour interval: 25

G51/B1-3146 Contour interval: 25

Standard curves for interpretation of the magnetic anomalies due to spheres have been derived. The anomalies in the vertical component, and the horizontal component in the direction of the traverse, are each found to be represented by a single family of curves. The horizontal component is found to be not represented by a single family, and separate curves for each field inclination and traverse azimuth are presented. Curves for the anomaly in the total intensity were not computed.

The Georgina Basin is a large Palaeozoic sedimentary basin extending from northwestern Queensland into the Northern Territory. Field parties from the Bureau of Mineral Resources mapped some of the Queensland part of the basin in the early 1950s, and the remainder in the period 1957-65; officers of the Geological Survey of Queensland participated in most of the Queensland surveys. Since 1957, petroleum exploration companies have made geological, gravity, aeromagnetic, and seismic surveys in selected areas, and the Bureau of Mineral Resources has carried out aeromagnetic and reconnaissance gravity surveys over most of the basin, and seismic surveys in Queensland and in small areas in the Northern Territory. Sixteen petroleum exploration wells have been drilled, but no commercial deposits of oil or gas were found; three deep stratigraphic holes were drilled by the Bureau, which also drilled an aggregate of about 3000 m in shallow scout holes. The Georgina Basin covers an area of about 325,000 sq km and extends in a belt trending northwest from latitude 25°S in northwestern Queensland to about latitude 18°S in the Northern Territory. The basin is about 1000 km long and about 500 km wide. The southwestern, western, northern, and eastern margins are defined by Precambrian outcrops, but the northwestern and southwestern margins are concealed by Mesozoic sediments. The position of the northwestern margin has not been resolved, but the southeastern margin has been defined approximately by gravity, seismic, and aeromagnetic surveys and by limited stratigraphic drilling.

Legacy product - no abstract available

Legacy product - no abstract available