The application of landsat-8 imagery and airborne gamma-ray spectrometric data for lithological mapping of Gabal Nuqara area, central eastern desert, Egypt

الملخص EN

This paper examines the integration of the spectral analysis of Multispectral Landsat-8 data and the airborne gammaray spectrometric survey followed by detailed field work and petrographic studies for geological mapping and locating radioactive anomalous zones at Gabal (G.) Nuqaraarea, central Eastern Desert, Egypt.

The Dokhan Volcanics of G.

Nuqara are characterized by their heterogeneity, complexity, toothy nature of their summits, steep slopes and very rugged topography.

Depending on traditional means, geological mapping of this rock unit is very difficult.

The promising results of Landsat-8 image processing, including Colour Band Composites and spectral transformation techniques (Principal Component Analysis, Minimum Noise Fraction and Band Ratios) and the results of airborne gamma-ray spectrometric data processing are verified and confirmed in the field by identification of the different lithological units and alteration types; the integrated work is validated further through petrographic studies.

The results of these techniques are integrated and combined to construct a precise geological map (scale 1: 50, 000) for the study area.

Accordingly, G.

Nuqara Dokhan Volcanics are classified into two members: 1) the lower intermediate member comprising andesite, dacite and quartz-dacite and their equivalent tuffs, and 2) the upper felsic, which is also classified into rhyodacites and their equivalent tuffs and the rhyolites with their equivalent tuffs.

In addition, the younger granites are discriminated from the older ones.

The radio element maps are correlated with the processed Landsat-8 images in order to delineate possible radio element potentialities at the G.

Nuqara area.

Uranium anomalies are encountered at G.

Mohamed Rabbah, the area around Wadi El-Barud and sporadic zones in felsic Dokhan Volcanics.