REMOTE SENSING-BASED GEOLOGICAL MAPPING OF THE AREA WEST OF AL-MADINAH, SAUDI-ARABIA

The paper describes the methodology and results obtained during the ge ological mapping of the area north-west of the Holy city of Al Madinah Al Munawwarah in Saudi Arabia on the basis of Landsat Thematic Mapper data at a scale of 1:100000. The application of very sophisticated im age processing algorithms yielded an image basis. The spectral units d isplayed were interpreted and then correlated to the lithological unit s along significant profiles during a field campaign. A thin section s tudy of the rock samples supported the lithological classification. Ge nerally, the region can be divided into two main geological units, nam ely the Precambrian basement rocks and the basaltic extrusive rocks of Harrat Al Rahat plateau which is covering the basement rocks in the e ast and the southeast. The basement rocks consist of a wide range of i ntrusive sedimentary and extrusive series, all metamorphorised with va rying intensities. The lack of vegetation cover and the effective meth ods used in the remote sensing data interpretation allowed a practical ly clear distinction between the different lithological units, as veri fied during the field work. This result testifies to the high value of the application of remote sensing data in Saudi Arabia.