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The spatial distribution of the South Australian gravity station network (over 65 OOO stations) can be approximated by a fractal point set of correlation dimension 0, = 1.4. The fractality is established over more than 2 decades of distance. The fractal nature of the grid is possibly due to the multistage decisions involved in establishing a network; in each step, previously unexplored areas are dissected by geophysical traverses, as in the classical fractal fragmentation process. It is shown that we cannot observe the short-wavelength components of the gravity field if the dimension of the network is less than two and any attempt to interpolate onto a regular grid could lead to spurious anomalies due to aliasing.

The Thunderbird heavy mineral sand deposit is located in Canning Basin of Western Australia and is hosted by Jurassic-Cretaceous fine sands and silts. The large areal extent, width, grade, geological continuity and grainsize of the Thunderbird deposit are interpreted to have formed in an off-shore, sub-wave base depositional environment. The Thunderbird mineralisation is hosted within a well-sorted and rounded fine to very-fine-grained sand unit which is over 90 m thick and contains abundant heavy minerals (up to 40% HM). Mineralisation occurs as a thick, broad sheet-like body striking northwest, and dipping shallowly to the west and southwest, extending from surface to a maximum drilled depth of 155 m. The heavy minerals suite in the Thunderbird deposit is comprised of altered ilmenite, ilmenite, pseudorutile, haematite, goethite, leucoxene, zircon, rutile, anatase and monazite, with very minor amounts of tourmaline, spinel, staurolite and andalusite. The minerals are finer-grained than most deposits currently being mined.

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