SALTMAP ? airborne EM for the environment

Abstract

There is increasing recognition that electrical conductivity is an important diagnostic parameter of the near-surface in the applications of land degradation monitoring, ground-water exploration and geological mapping. Airborne electromagnetic (AEM) geophysical surveys provide a means of measurement of ground-conductivity distributions. SALTMAP, a new AEM survey system being developed in Australia by World Geoscience Corporation and the CSIRO Divisions of Exploration Geoscience and Water Resources, has been designed specifically to make high-resolution measurements of the conductivity distribution within the regolith. This results from the broadband nature of the transmitter and receiver antennae and high-speed signal processing incorporated in SALTMAP. SALTMAP will record secondary fields at frequencies in excess of 50 kHz ? unprecedented for a broadband AEM system ? enabling measurement of near-surface conductivity distributions. In resistive terrain, SALTMAP's specifications give it a unique ability to discriminate mineral exploration targets to some depth. As a result of the broad bandwidth of SALTMAP, it is susceptible to a wide range of interference problems which can be overcome only with powerful signal processing equipment that has only recently become available. A three-component receiver antenna has been incorporated in SALTMAP to provide full measurement of the secondary field. All SALTMAP components are under the control of flexible computer algorithms to enable SALTMAP to be adapted to a wide range of applications in a wide range of conditions. SALTMAP provides a powerful new tool for land and water resource authorities and mineral explorers. It will provide detailed information about the hydrogeology over large areas at a fraction of the cost of normal land treatments. Improved interpretation of regolith conditions will result in a significant increase in efficiency of implementation of strategies for sustainable land use and rehabilitation.