AIRPHOTO INTERPRETATION AS AN AID TO LITHO - STRUCTURAL MAPPING IN TROPICAL TERRAIN - THE NEW FEDERAL CAPITAL CITY SITE, ABUJA, NIGERIA

Authors : Murat AVCI

Pages : 65-75

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Publication Date : 1988-01-01

Article Type : Research Paper

Abstract :The Federal Capital Development Authority of Nigeria requested that an engineering geological investigation of the proposed New Federal Capital City Site at 1: 25.000 scale be carried out for suitability purposes. Mapping with conventional field methods alone proved to be insufficient due to the concealed terrain conditions in the area. Two different scales (1: 40.000 and 1:10.000) of aerial photographs were used which have revealed three main bedrock units and the entire structural framework of the area. Airphoto interpretation data shows lithological banding running NNE — SSW and fractures developed mainly in NW — SE and NE — SW directions. Through this information a major tectonic event has been inferred, resulting from a principal stress acting WNW—ESE.The directional frequency and the length of fractures show variations according to rock type. The metaigneous rocks gave high fracture density and frequency values, whereas metasedimentary rocks yielded low values of the same parameters. 
Keywords : AIRPHOTO, LITHO, STRUCTURAL