Anomalous geomagnetic variations and the concentration of telluric currents in south-west Queensland, Australia

• Published in: Geophysical Journal International
• Main Authors: Woods, D. V., Lilley, F. E. M.
• Format: Text
• Language: English
• Published: Oxford University Press 1980
• Subjects: Articles; Southern Ocean; Queensland
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/62/3/675; https://doi.org/10.1111/j.1365-246X.1980.tb02599.x

A pattern of geomagnetic fluctuations in central Australia shown by a magnetometer array with instruments spaced at distances of order 100 km has been investigated in detail by a follow-up study in south-west Queensland with array instruments at distances of order 20 km apart. On a regional scale the pattern is simple and two-dimensional, and is evidently correlated with the spatial distribution of highly conducting sediments in the Great Artesian Basin of eastern Australia. Numerical studies of induction in two-dimensional models of the basin structure adequately account for the magnitude and scale of the observed regional pattern of anomalous fluctuation fields. The smaller scale array disclosed details in the regional pattern for which interpretation proceeds in terms of current concentration in an equivalent current sheet. This sheet represents the integrated current flow in the upper 5 km of the crust, the maximum permissible depth of such a sheet current. The interpreted current distribution can be only partly explained by the known structure of the basin. Additional conductive structures must be present either within the basin or immediately below the basin in the basement rocks. Taking into account knowledge of a conductivity anomaly in southern Australia, it is hypothesized that a current channel may exist from north to south across the Australian continent, joining the Gulf of Carpentaria to the Southern Ocean.