Crustal structure studies in Tasmania

A regional gravity survey of Tasmania has revealed that the crust is of normal continental thickness (35 to 40 kms), increasing slightly under the Central Plateau region and thinning rapidly at the continental margin. The \regional\" field due to the variation in crustal thickness has been obtained by approximating the observed data using a terminated Fourier series; the trigonometric functions having been orthogonalised with respect to the irregularly spaced data points by the Gram-Schmidt method. A time-term analysis of the Bass Strait crustal refraction data indicates near normal thicknesses in Tasmania and intermediate thicknesses in Bass Strait (23-28 kms). Spectral analyses of high-level aeromagnetic data have indicated that if the source layers of magnetic anomalies can be considered to give rise to a \"white\" spectrum then the depth to the source layer is given by the gradient of the logarithm of the spectrum."