Murray Basin Magnetotelluric study

Abstract The Murray Basin is geologically featureless, has been sparsely covered by geophysics, and is penetrated by a few scattered wells. Only drilling and reflection seismic work have provided consistently reliable depth information. They have indicated the presence of narrow troughs, which contain more than 3 km of Palaeozoic sediment, covered by basement highs with less than 300 m of Mesozoic and Cainozoic cover. Six widely spaced magnetotelluric (MT) sites were occupied in the north central Murray Basin. Results showed a 5 km thick horizontal section at Pooncarie, with a probably average porosity of 10%. Higher porosities, and probably a thicker section, were indicated near Little Topar, but the structural complexity there requires that additional data be acquired for positive interpretation. A persistent conductivity increase near 100 km suggests that the method may respond well to the base of the tectonic plate. The MT method appears well suited to the onshore exploration problems currently faced ...