INTEGRATION OF LANDSAT ETM+ IMAGERY AND AIRBORNE GEOPHYSICAL DATA TO DISCRIMINATE ROCK UNITS AND RING COMPLEXES IN GEBEL EL NAQA AREA, SOUTH EASTERN DESERT, EGYPT.

The prime aim of this work is to demonstrate how can the integration of geophysical and satellite imagery data lead to discrimination and identification of the rock units and ring complexes. The spectrometric maps are useful to illustrate the boundaries of igneous and metamorphic rocks. The radioelement ternary map of K%, eU and eTh (in RGB) provide, on a single display, an overall picture of the radioelement distributions across the study area. Isolation of the magnetic anomalies was conducted for reduced to magnetic pole map into deep regional and shallow residual components. Forward modeling was applied only to the El Naqa ring complex. A 2-D magnetic model was used to account for the limited extent of the intruded zone perpendicular to the flight lines. From the interpretation of false colored composite images of ETM+ bands 7, 4 & 2 in RGB, it can be easy to distinguish the boundaries between rock units, according to color differences and photogeological characteristics of the rocks, in addition to the band ratio combination of ratio, 5/7, 5/4, 3/1 in RGB, respectively. The results revealed that, to the southeast part of the survey area at Gebel El Waqif, the correlation between the mapped gniess and schist and the spectrometry response as recorded becomes progressively poorer. This contrast is due to distinct high total count, potassium and thorium with a lower extent for uranium and appear to be magnetically low which reflect gneissose granite exposures. There are two ring complexes, which appear at the southern part for the study area in the landsat imagery. They are characterized by their cone and circular shape. The magnetic interpretation of the El Naqa ring complex demonstrates that, the 2-D structure of the ring complexes is not restricted to the brittle upper crust but can extend through the crust as well. Statistical analyses of interpreted lineaments affecting the study area revealed that the predominant structural trends arranged in a decreasing density order are, NE-SW, NW-SE, and E-W