Utilization of supervised classification in structural and lithological mapping of Wadi Al-Marwah Area, NW Arabian Shiel
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ORIGINAL PAPER
Utilization of supervised classification in structural and lithological mapping of Wadi Al-Marwah Area, NW Arabian Shield, Saudi Arabia Adel Zein Bishta & Abdullah Rasheed Sonbul & Wuadee Kashghari
Received: 17 March 2013 / Accepted: 19 July 2013 # Saudi Society for Geosciences 2013
Abstract Wadi Al-Marwah area is located in the northwestern part of the Arabian Shield, Saudi Arabia. It is mainly covered by Precambrian igneous and sedimentary rock units. This area was not subjected to previous detailed lithological or structural mapping. This study aims to apply supervised classification technique of remotely sensed digital satellite data of Landsat 7 for detailed lithological and structural mapping of the area. The fusion between multispectral Enhanced Thematic Mapper (ETM)+ data and high-resolution panchromatic ETM+ band-8 produced a color composite fused image for the study area, scale 1:50,000. The structural lineaments of the study area were extracted and interpreted from the digital imageries data. Little discrepancies or improvements were detected when combining the supervised classification results with the Landsat ratios or principal component analysis. These highlighted the benefits of multispectral classification, especially in terms of lithologic discrimination. The overall results of image processing techniques, applied in this work, were excellent and succeeded in the performance of a more detailed and accurate lithological and structural maps (scale 1:50,000) than the previous published maps for the investigated area. Keywords Lithological or structural mapping . Wadi Al-Marwah . Supervised classification
Introduction Wadi Al-Marwah area represents a part of Al-Wajh quadrangle, which is located in the northwestern part of the Arabian A. Z. Bishta (*) : A. R. Sonbul : W. Kashghari Faculty of Earth Sciences, King Abdulaziz University, Jeddah, Saudi Arabia e-mail: [email protected]
Shield, Saudi Arabia. It is situated north of Umm-Lajj area, bounded by latitudes 26°05′00″N and 27°22′00″N and longitudes 36°46′00″E and 37°02′00″E (Fig. 1a). The investigated area is covered by a simple drainage pattern, marked by parallel Wadis (dry valleys), draining southwest into the Red Sea, such as Wadi Al-Marwah, Wadi Baladiyah, Wadi Tufayyah, and Wadi Al-Arjah. The relief of the study area rises from sea level to a height of around 1,000 m in the northeast of the study area that contains some hills rising between 50 and 300 m height (Fig. 1b). The investigated area is covered by Precambrian metasediments and intrusive igneous rocks belonging to the Arabian Shield, which are covered by Quaternary sediments. Reconnaissance geological mapping of Al-Wajh quadrangle was carried out by the traditional methods, in scales 1:100,000 (Sheet 26/36 C and D, 1979) and 1:250,000 (Sheet JED5, 1979). Many authors carried out lithological mapping, depending upon multispectral classification method only, and some others depending upon image ratios and/or principal component analysis (PCA) methods (e.g., Sultan e
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