Available Datasets

South Australian Geoscientific GIS dataset
The intensive data capture programs initiated by the Geological Survey of South Australia over the last few years has resulted in an extensive collection of data, the compilation of which has now been assembled into the South Australian Geoscientific Geographical Information System (GIS). This spatially integrated bibliographic collection of data is a state-wide integration of geological, geophysical, geochemical and cultural data aimed at distributing regional geoscientific information for exploration and research (www.pirsa.com). A number of selected databases were selected from the South Australian Geoscientific GIS dataset. These include summary digital geology of rock outcrops, basins and geological and tectonic provinces. In addition, databases of drillhole stratigraphy and geochemical sampling related to single points on the ground were selected for analysis and interpreted.

South Australian Gravimetric dataset
The regional gravimetric field dataset used in this study was derived from Primary Industry and Resources, South Australia (PIRSA). This dataset is a reduced and corrected Bouguer Gravity map covering the entire state of South Australia (Figure 2). The station spacing configured for acquisition of this dataset is variable with an average spacing of approximately 8 km. Each gridded image-cell is also of approximately 200m.

Figure 2. Gravimetric dataset of South Australia.

Image Enhancement
The gravimetric dataset gridded by MESA have been processed using the Intrepid™ software. This was performed using filtering algorithms to visually enhance the effects of selected geological features, thereby enhancing different facets of the dataset. The filter used in this investigation is a matched filter (Cowan & Cowan, 1993). A matched filter, in theory, provides a separation of frequencies for different depths. The image will ideally contain information from a certain depth level while signals from other depths are attenuated. All images were subsequently displayed in ERMapper™.

Petrophysical Investigations
Rock density data was used as the primary constraint for the geophysical modelling. However, published information on the measurements of densities for rocks of the Gawler Craton and its surrounds is limited. The average rock densities used in this study are presented in Table 1, the majority of which were derived from Gow (1997). Density estimates inferred for particular rock types are also presented in Telford et al (1995). All densities used in the modelling have assumed heterogeneous characteristics that are derived from geologically reasonable estimates and therefore represent a wide range of values.

Table 1. Rock density values of major crustal blocks of the Galwer Craton and surrounds (after Gow, 1997 & Betts, 1999).