STRUCTURAL FRAMEWORK OF THE CENTRAL EASTERN DESERT OF EGYPT, USING REMOTE SENSING TECHNIQUES AND GROUND DATA

Abstract

The remote sensing technology represents the most advanced modern techniques used for solving the structural and geological problems. Digital Landsat-5 Thematic Mapper (TM) were evaluated for lithological mapping, structural framework interpretation and mapping, as well as the tectono-metallogenic investigation of the Central Eastern Desert ofEgypt. The crystalline basement rocks of the Central Eastern Desert represent a most important part of the Pan-African Precambrian schield. This 'because it contains all varieties of the basement rocks, which represented by an excellent exposure of infracrustal, rocks (gneiss, migmatities, mylonites and their derivatives) that structurally overlain by supracrustal Eastern Desert ophiolitic melange of Ries et a!, 1983. As well as, un-metamorphosed rocks, and intrusions oflate- to post- tectonic granits and dyke swarms. For visual enhancement of Landsat data Decorrelation Stretching (DS) of the three least correlated bands (7, 4,1) yielded an overall good lithologic enhancement. PC (Principal Component) analysis resulted in a higher signal-to-noise ratio when standardized coefficients were used instead of the covariance matrices. Four bands, instead of six input bands, proved sufficient to produce good PC images with higher spectral contrast. IHS-RGB transformation is good to avoid the image noisy and lake of topographic details. Decorrelation Stretching (DS) is also a valuable tool in providing a higher number of band triplets, and omission of noise-dominated PCs during retransformation, this generally gave substantial enhancements. Band ratioing yielded geologically useful images, whereby both spectral and morphological informations are preserved. Spatial convolute filtering (Edge-Enhancement) is the very useful digital processing technique for detection and interpretation of lineaments and other linear structures. Generally, combinations of results collected from different enhancement methods are suitable for comprehensive results during image interpretation. Digital classification of spectral and textural parameters proved less useful in the present . context.