Groundwater is a common source of drinking supply in Australias arid zone. The constituents in groundwater can limit its use either for drinking or for other domestic purposes. This paper discusses those constituents. It also highlights popular misconceptions about water-quality problems associated with groundwater, and encourages radical rethinking to ensure that people in the arid zone can use available water supplies appropriately to maintain a healthy lifestyle.

Meteorites are associated with five impact structures in Australia. Three of them are group IIIAB irons (Wolf Creek, Henbury, and Boxhole), Veevers is a group IIAB iron, and material recovered from the crater at Dalgaranga is a mesosiderite stony-iron. The impacts range in age from a few thousand years (Dalgaranga, Henbury, Veevers, and Boxhole) to 300,000 years (Wolfe Creek Crater). Metallographic studies of the surviving fragments at some of the craters show that impact damage ranges from simple fracturing, through shock-hardening of metal, to plastic and shear deformation, reheating and attendant recrystallisation, and, ultimately, melting. Details of the microstructures of surviving fragments of iron meteorite from the craters suggest that shear deformation may have been an important mechanism in the disruption of the projectiles. Frictional heating from viscous drag between projectile and target, and from rapid shear deformation within the projectile, may be sufficient to melt and vaporise significant portions of the projectiles and account for the large deficit of meteoritic material from Australian impact craters.

Legacy product - no abstract available

Until about 1950, the southwest Pacific region was thought by many to be the foundered eastern half of Greater Australia, Tasmantis. The Outer Melanesian arcs defined the northern part of the Tasmantis boundary to the Pacific Ocean basin. Others considered the Inner Melanesian arcs to be the expanded rim of the Australian craton, the outwardly propagated expression of the Tasman Geosyncline. With the surge of exploration after World War II, new data showed that the outer islands could not be matched with island-arc models such as the Sunda Arc, and that New Caledonia, of the inner arcs, seemed increasingly to have Tasman Geosyncline affinities. By 1968, the land and sea data had produced a cluttered and confused picture, ripe for the application of new global tectonic models. After 1968, the Tasman Sea was shown to be a product of Late Cretaceous seafloor spreading and New Caledonia was accepted as part of the expanded rim of eastern Gondwana. The sea floor between the inner and outer chains was relatively young and the product of complex seafloor spreading. Over recent years, the southwest Pacific has in many respects been a showcase of plate tectonic theory. The region is intensely mobile. The obliquely convergent northern Indo-AustralianlPacific plate boundary carries great crustal blocks as allochthons to join others in eastern Indonesia. These crustal blocks also undergo vertical and rotational movement. The outer island chains do not fit the conventional models of an island arc - they are hybrid entities made up of the byproducts of subduction and of exotic terranes; as arcs, they continually change composition, form and configuration, even as they are being built. These outer chains are components of what is here called an accommodation boundary .

Contents: 1.Strusz DL. Brachiopods from the Silurian of Fyshwick, Canberra, Australia. 2.Young GC. Further petalichthyid remains (placoderm fishes, early Devonian) from the Taemas-Wee Jasper region, New South Wales. 3.Nicoll RS. Multielement composition of the conodont species Polygnathus xylus xylus Stauffer, 1940 and Ozarkodina brevis (Bischoff and Ziegler, 1957) from the upper Devonian of the Canning Basin, Western Australia. 4.Jones PJ. Treposellidae (Beyrichiacea: Ostracoda) from the latest Devonian (Strunian) of the Bonaparte Basin, Western Australia. 5.Dickins JM. Late Palaeozoic glaciation. 6.Shafik S. Calcareous nannofossils from the Toolebuc Formation, Eromanga Basin, Australia. 7.Belford DJ. Late Albian planktonic foraminifera, Strickland River, Papua New Guinea. 8.Smith MJ, Plane M. Pythonine snakes (Boidae) from the Miocene of Australia. 9.Casey JN, Romot N, Shergold JH. Armin Aleksander Opik (1898-1983). 10.Laurie JR, Shergold JH. Phosphatic organisms and the correlation of early Cambrian carbonate formations in central Australia. 11.Shergold JH, Cooper RA. Late Cambrian trilobites from the Mariner Group, northern Victoria Land, Antarctica.

Thematic issue

Thematic issue

BMR journal of Australian geology & geophysics ; v. 6, no. 4. "Thematic issue" Contents: 1.Trudinger PA. Origins of sulphide in sediments. 2.Saxby JD. Organic matter in ancient ores and sediments. 3.Plimer IR. Water depth - a critical factor for exhalative ore deposits. 4.Philp RP. Diagenetic organic matter in Recent sediments and environments of deposition. 5.Bauld J. Geobiological role of cyanobacterial mats in sedimentary environments: production and preservation of organic matter. 6.Ferguson J, Burne RV. Interactions between saline redbed groundwaters and peritidal carbonates, Spencer Gulf, South Australia: significance for models of stratiform copper ore genesis.

Available geological and geophysical data for the dominantly Devonian Darling Basin of western New South Wales indicate a high risk for petroleum exploration. Hydrocarbon prospectivity is confined to the concealed western Darling Basin, where block-faulted, graben-like troughs contain a generally thick sequence of Middle Devonian to Lower Carboniferous continental sediments, underlain by Lower Devonian marine sediments. Geochemical data for cores from BMR Ivanhoe No. 1 and from thirteen petroleum exploration wells held on open file at BMR are used to evaluate source rock potential and organic maturation levels. The continental sediments have no source potential. The marine Lower Devonian Amphitheatre Formation has a generally low organic carbon content, is thought to be gas prone, and is thermally mature to overmature for oil generation. The geochemical data support the hypothesis that trough flanks and margins, where sediments have not been too deeply buried or thermally altered, offer the best prospects for preservation of source and reservoir rocks. On the basis of the limited data available, the eastern flank of the Lake Wintlow High - Wilcannia High is considered the most prospective region of the Darling Basin.

The development of cross-spectral techniques for investigating the relation between gravity and topography has led to the representation of isostatic processes in terms of mathematical filters, or admittance functions. These filters can easily be constructed by application of Greens equivalent layer theorem. The rheology of the lithosphere principally controls the process by which isostatic compensation is achieved. As examples, admittance functions representing the isostatic process defined by elastic and visco-elastic rheologies are developed. By using admittance functions, the calculation of the free-air gravity anomaly for complicated topography, isostatic schemes, or rheology becomes computationalIy more efficient and simple compared to the more conventional line-integral methods.