Regional AEM Surveys for Namibian Government

Abstract

Regional surveys using the TEMPEST208 airborne electromagnetic system were acquired for the Geological Survey of Namibia in 2011. The TEMPEST208 is the lowest cost airborne electromagnetic system available currently worldwide and was selected to test a cost effective means of covering the country with AEM and particularly to map thickness of the Kalahari Sequence to open new areas for mineral exploration.. This review of the data acquired showed that; â?¢ TEMPEST208 did have some noise problems but significant improvements could be achieved with minimal work by the contractor. â?¢ TEMPEST208 can map areas of thin (0-60m), to medium (~100m) and thick cover (>150m) Kalahari Sequence. In areas of thin cover conductors can be detected in the underlying basement. In areas of medium cover an estimate of thickness of the Kalahari (with LEI) is probably possible but in areas greater than 150m the system generally did not detect the base of the Kalahari. â?¢ Comparison with detailed surveys done with standard TEMPEST and VTEM shows that TEMPEST208 detected most of the features seen in surveys by the more sophisticated system. â?¢ The data will be useful for explorers selecting best areas for exploration particularly where the Kalahari Sequence is less than 60m. It is recommended that; â?¢ Small upgrades to the TEMPEST208 system would assist in reducing noise particularly in relation to GPS position of the receiver bird. â?¢ Water wells be logged with downhole conductivity to provide better modelling parameters, for input to Layered Earth Inversions. â?¢ The GSN should extend the survey with similar specifications to other parts of the country covered by Kalahari Sequence.