THE LARGE-SCALE ELECTRICAL-CONDUCTIVITY STRUCTURE OF AUSTRALIA

A widely-spaced array of three-component recording magnetometers has been used to make a natural geomagnetic induction reconnaissance of the whole Australian continent. The coast effect is well observed, as are two major continental electrical conductivity anomalies known previously. While there may be considerable small-scale detail yet to be mapped, the gross electrical conductivity structure of the continent appears relatively simple. Taking into account the known geology, the regions of high electrical conductivity appear to be associated with the sedimentary basins that separate major continental cratonic blocks. The two previously known conductors may be electrically connected to form a major continent-wide ''Australian intercratonic conductivity zone''.