Technical Papers - Airborne Electromagnetics

Resistive-Limit, Time-Domain AEM Apparent Conductivity

Peter Annan, Richard Smith, Jean Lemieux, Michael D. O'Connell, and
Rolf N. Pedersen, Fugro Airborne Surveys
2060 Walkley Road, Ottawa, Ontario, Canada, K1G 3P5 

Abstract

On-time measurements, which can be obtained with existing airborne transient electromagnetic (AEM) systems, are used to map the apparent conductivity of the ground. Such measurements can extend the conductivity aperture of these systems substantially at the low end of the conductivity range.

A theoretical analysis is given that provides a simple, approximate, resistive-limit solution for any transient EM waveform. The approximate result is compared to the full-numerical result for the specific case of the GEOTEM system over a conductive half-space. Examples of GEOTEM data reduced to apparent conductivity using the approximate analytical solution are presented from surveys for kimberlites and massive sulfide deposits.

Presented at the International Workshop on Airborne Electromagnetic Methods, Tucson, AZ, September 13-16, 1993. 

GEOPHYSICS, VOL. 61, NO. 1 (JANUARY-FEBRUARY 1996); P. 93-99, 9 FIGS. Manuscript received by the Editor May 6, 1994; revised manuscript received April 3, 1995. © 1996 Society of Exploration Geophysicists. All rights reserved. 

For a paper copy with a better reproduction of Figure 7, please email Richard Smith

Download Paper (PDF 631 Kb)