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  • A hydrogeological map-set of the Lake Amadeus-Ayers Rock region in central Australia has been prepared as a pilot project for a national groundwater resources inventory. The maps in the set were compiled on a computer graphics system at 1:250000 scale from layers representing topography, bedrock geology, surficial geology, hydrodynamics, hydrochemistry, and water-bore locations. The quantitative information was obtained from a microcomputer database, and the geological and topographic information was digitised from specially revised maps. As the hydrogeological data are sparse it was decided to publish the main maps at 1:500000 scale. For three areas where more detailed information was available, inset maps at 1:100000 scale are presented. The region mapped is arid; annual rainfall is about 250 mm and potential evaporation close to 3000 mm. Groundwater recharge is of the order of I mm/year. Important aquifers are surficial Cainozoic sand and calcrete, and bedrock sandstone units including the Palaeozoic Pacoota Sandstone and Mereenie Sandstone. Groundwater varies in quality from 0.4 g/L to more than 200 g/L total dissolved solids. Groundwater converges from the north and south towards a southeast-trending chain of playas, where it discharges by evaporation. Hydrochemical evolution is apparent along groundwater flow paths. Fresher water, generally bicarbonate-rich, occurs close to the hilly recharge areas and in the calcrete. This evolves to highly saline chloride-rich brines in the playas, by processes of solution, precipitation of minerals, and evaporative concentration. Groundwater supplies have been developed for the Yulara tourist resort, the largest settlement in the area, although the water, derived from Cainozoic sands, is desalinated for use in domestic supplies. For a proposed tourist resort at Kings Canyon, a water supply is being developed from bedrock units, mainly the Pacoota Sandstone. Single bores are scattered through the region, supplying cattle stations and Aboriginal settlements. In this hydrogeologically complex region, extrapolation from conceptually known areas is difficult. The detailed assessment of ground water resources will require additional drilling.

  • Crustal dynamics throughout geological history have played an important role in the development of sedimentary basins. A basic knowledge of major crustal structures is, therefore, crucial to any interpretations aimed at modelling particular basin systems. This Bulletin contains papers by authors from a number of geoscience institutions and companies on various aspects of crustal and basin development along an 1100 km east-west transect in southern Queensland, the Eromanga-Brisbane Geoscience Transect In particular, deep seismic profiling along this transect has enabled, for the first time, a 3-dimensional interpretation of deep structures and processes which have controlled the development of major basin systems in eastern Australia. Complete answers to all questions on basin development are still evolving, but the papers presented in this Bulletin, together with the 1:1 000 000 scale map folio, provide a much improved basis for further, detailed investigations. The Eromanga-Brisbane Geoscience Transect crosses three major basement provinces in eastern Australia: 1) the Thomson Fold Belt under the central Eromanga Basin and its infra-basins, 2) the northernmost Lachlan Fold Belt under the Taroom Trough of the Bowen Basin and Surat Basin, and 3) the New England Fold Belt under the Clarence-Moreton Basin. Basement geology in this region has, until now, been only poorly understood because it is largely obscured by the Mesozoic cover rocks of the Eromanga, Surat and Clarence-Moreton Basins. However, the application of geophysical techniques (seismic methods in particular) in recent years has enabled a much better understanding of the crustal architecture and processes likely to have been involved in the development of the major basins. Such an understanding provides the framework for more detailed investigations directed primarily at economic resources of oil, gas, coal, groundwater and many minerals.The precis paper at the end of this Bulletin should be consulted for a summary of geoscience results. It is evident from these results that the transect interpretation has now firmly established concepts of crustal-scale ramp structures, multiple intra-crustal detachment surfaces, strike-slip fault architecture, lower crustal magmatism/underplating, Moho remobilisation, and intra-crustal terranes into the geological reconstructions of southern Queensland. In so doing, it has played a major role in developing a better understanding of the sedimentary basins of eastern Australia.

  • 95% coverage, north east corner missing E53/B1-132 Vertical scale: 10

  • 15% coverage north west F53/B1-202 Vertical scale: 500