AIRBORNE GAMMA RAY SPECTROMETRY AND MAGNETIC DATA EVALUATION OVER THE EAST WADI LIGAN AREA, EASTERN DESERT, EGYPT

Abstract

The studied Wadi Ligan area is located in the Central Eastern Desert of Egypt between latitudes 2750’ N- 2805’ N and longitudes 3210’ E- 32*40’ E and approximated 2052 km2. The geology of this areaconsists, for the most part of exposures, of Upper Cretaceous, Eocene and Quaternary Wadi sediments. Precambrian metavolcanics, metagabbro-diorite complex and younger granites are exposed in the east of the area. The purpose of this study is the analysis, evaluation and interpretation of the aerial radiospectrometric and magnetometric survey data acquired over East Wadi Ligan area. The interpretation is mainly devoted towards the achievement of three main objectives namely: geological (lithological and tectonical) mapping, mineral exploration especially uranium anomalous zones and environmental radiospectrometric monitoring of the area under consideration. The area under consideration has been involved in the aerial multi-channel gamma-ray and magnetic survey conducted by Aero- service Division, Western Geophysical Company of America, in 1983, over a large segment of the Eastern Desert of Egypt, as a part of the Mineral, Petroleum and Ground Water Assessment Program (MPGAP). Conversion of the gridded data of the aerial magnetic and multi-channel gamma-ray survey -conducted over the studied area- to a common image format made it possible to display and manipulate these originally non-image data by standard digital image processing technique. In this way some interesting false colour composite images were produced for some selected combinations from the various radiometric parameters. These radiometric composite images offered much in terms of lithologic discrimination based on colour differences and showed distinct efficiency in defining areas where different lithofacies occur.