Geoscience Australia in collaboration with the Geological Survey of Western Australia (Royalties for Regions Exploration Incentive Scheme), the Department of State Development South Australia and AuScope funded the Eucla-Gawler 2D deep seismic survey. The seismic survey acquisition and processing were managed and processed by Geoscience Australia. Geokinetics Australasia Ltd were contracted to collect the Eucla-Gawler 2D deep seismic reflection survey from November 2013 to February 2014. Deep seismic reflection data and gravity readings were acquired along the 834 km seismic line. Magnetotelluric (MT) data (Duan et al, 2015) were also acquired along the seismic line after the completion of the seismic survey. The main objectives of the project are to acquire deep crustal seismic data to (Geoscience Australia, 2013): (1) Image the crustal architecture of the geology underlying the Eucla Basin and its relationship to the Gawler Craton to the east and the Yilgarn Craton to the west; (2) Establish the subsurface extent of the Eucla Basin and look for large structural zones that may have provided fluid pathways for mineralisation.

Some modifications to methods of relief peel preparation and latex replication have been made for use in the study of the evaporite and carbonate sediments and algal-mats of the peritidal regions of Spencer Gulf, South Australia. The use of hessian backing material enables araldite relief peels to be made of large faces of unconsolidated materials. A technique of cutting sediment cores to provide an undisturbed surface for preparing a peel has been developed to overcome problems of core disturbance or contamination caused by conventional methods of core sawing or core extrusion. Plaster-of-Paris moulds were taken of algal-mat surfaces, including some subject to daily tidal inundation, without extensively damaging the mats. Rubberlin latex casts of these moulds provide detailed replicas of the mat topography.

The GABHYD model was developed to provide a tool for predicting the effects of groundwater development alternatives for the Great Artesian Basin. Data from flowing artesian wells are averaged and discretised to provide the data base for a finite difference numerical model defined on a regular square grid. A quasi-three-dimensional simplification is employed to represent the different aquifers in the vertical direction. The model was calibrated using a newly developed direct method. The resulting model was found suitable for predicting regional effects of groundwater management for the major artesian aquifers for which adequate data are available. As an example the model shows that controlled pumping of 900 l/ s in one area of South Australia creates drawdowns of 23 m locally, 3 m 100 km away and 1.5 m at a distance of 110 to 170 km. The model also predicts that drawdown for the year 2000 will be little more than these figures.

The major gravity anomalies in central and western Australia occur as elongate dipoles, either in isolation or in a series. Each dipole is thought to be caused by an abrupt change in mean crustal density at the junction of two crustal blocks and by the associated isostatically compensating masses. Typically one block has along its margin a strip with anomalously high mean crustal density, and the other block has normal density crust covered by several kilometres of low density sediment. The observed anomalies are consistent with the anomalous masses being isostatically compensated by variations in the thickness of the crust, the crustal thickness variations being gradual and extending to about 100 km from the boundaries of the anomalous bodies. The crustal block boundaries inferred from dipole anomalies correspond in position with the crustal block boundaries inferred from geology, and approximately with the position of block boundaries inferred from changes in the gravity trend pattern. Usually the block with younger basement has high density material along its margin, and the other, older block is covered with sediment; both these features are likely to be caused by the process that created or emplaced the younger block. The presence of relatively dense material high in the crust along the margins of the younger blocks suggests that younger blocks are not superficial features on a uniform old crust. The dipole anomalies on the Australian Precambrian crust are similar in magnitude and tectonic position to those recognised at Precambrian province boundaries in Canada.

Concentrations of heavy minerals in the prograded coastal sequence of southeastern South Australia are generally low, partly as a result of the high content of locally derived biogenic carbonate in many of the sediments. Terrigenous input to the nearshore region appears to have been relatively slight, and the operation of concentrating mechanisms minimal. The highest heavy-mineral concentrations recorded in the area (up to 1.2% total heavies) occur in a sand of probable Pliocene age underlying Quaternary beach and dune deposits. In general, the heavy-mineral suite present in the sediments consists of between 25 and 45 percent magnetite-plus-ilmenite, 5 and 20 percent leucoxene, 5 and 25 percent zircon, 5 and 30 percent tourmaline, and between 0 and 10 percent amphibole, epidote, rutile and garnet. Andalusite, sillimanite, kyanite and staurolite occur as minor components in many assemblages. Sialic igneous, reworked sedimentary, metamorphic and to a slight extent mafic igneous components are present. Probable sources include the igneous rocks of the Padthaway Ridge, metamoraphic and sedimentary rocks of the Fleurieu Peninsula and Kangaroo Island, and older Tertiary sediments. Variations in the suite are defined by cluster and Q-mode factor analysis. Higher concentrations of heavy minerals occur within the older (probably Pliocene) ridges of the western Victorian Murray Basin. These ridges which approximately parallel the southeast South Australian ridge sequence, are siliceous, and commonly contain thin bands of concentrated heavy mineral (up to 20% total heavies in the bands) in the lower part of the Parilla Sand. The suite is mineralogically mature (generally 50-70% opaque, 15-30% tourmaline, 3-5% rutile, 5-15% zircon and 1-3% others) and differs considerably from that present in the southeast South Australian sequence. The difference reflects differences in provenance of the two areas and the probable modification by intrastratal solution of the assemblages originally present in the older deposits.

Available data about recharge from irrigation areas in the Mallee and Riverine Plains zones of the Murray-Darling Basin are reviewed. The need for clear understanding of how data have been obtained and care in their use, and the need to clearly identify the aquifer which is being recharged and to specify appropriate time and space scales are emphasised. The usefulness of the data for numerical modelling is discussed. Available data are considered adequate for establishing regional priorities for action to reduce recharge. However, site-specific data are required for design of projects at the local or sub-regional scale. Monitoring of system performance during and after implementation is necessary to verify the accuracy of data used. Options available for recharge reduction are discussed. Recharge rates in the Mallee zone are very high, and significant reductions can readily be achieved. Many irrigated areas in the Mallee zone are already tile drained, so the main benefits of recharge reduction will be lower regional water tables and reduced groundwater discharge to the River Murray. Recharge rates in the Riverine Plains zone are generally much lower, although some areas of high recharge do occur. Options for recharge reduction are identified for use in appropriate circumstances, but it is considered that residual recharge rates are likely to exceed the safe discharge capacity of the underlying acquifers. Subsurface drainage of the more intensively irrigated areas will be required (as in the Mallee zone), to avoid significant losses of production and land degradation.

Widespread clearing of native vegetation has dramatically increased recharge in the Mallee region by up to two orders of magnitude. The resultant rising water tables have caused land salinisation problems in low lying areas and, in the long term, will increase saline groundwater inflows to the River Murray with a consequent rise in river salinity. Computer modelling suggests that, 50 years after the water table begins responding to the increase in recharge, an increase of 70 Electrical Conductivity (EC) units in river salinity will occur at Morgan. Broadscale revegetation in strategic areas adjacent to the river will reduce saline groundwater inflows, and the economic and social aspects of this measure should be investigated.