GEOLOGICAL MAPPING FROM THE REMOTE SENSING IMAGERY OF THE KEKEM AREA, CENTRAL DOMAIN OF THE PAN-AFRICAN FOLD BELT IN CAMEROON
ISBN 978-85-88783-11-9
Authors
1de Pesquidoux I, T.T.; 2Elvis Fang, K.
1UNIVERSITY OF YAOUNDE I Email: depesquidoux@yahoo.fr
2UNIVERSITY OF YAOUNDE I Email: elvis18289@alumni.itc.nl
Abstract
The Kekem area which is located in the southwest of the Cameroon central shear zone within the central domain of the pan-African fold belt is made up of an association of paleoproterozoic and neoproterozoic rocks. These rocks are partially overlain by tertiary basalts and trachytes of the Cameroon volcano-tectonic line. The geographical extension of various units as well as the geometrical relationship between them is a matter of debate. As a result, various controversial models of the pan-African tectonic evolution have been developed and debated upon. In order to improve our knowledge, a new geological mapping approach using remote sensing imagery in synergy with field data of geological survey has been implemented. A pre-processing treatment of Landsat TM satellites images with the aid of ENVI sofware first focused on geometric and radiometric corrections followed by an image processing which included various enhancement procedures, band combinations (Landsat band ratios 5/1, 3/7, 5/7 and 5/4), R: G: B colour composites of 7:4:1, 7:5:4, 1/3:5/7:3/5 and 4/5:6/7:4/6 were used. Ratio images as expected enabled us to distinguish two units: 1) a Precambrian basement which is made up of a combination of intrusive and metamorphic rocks; 2) and extrusive rocks. The colour composite images went further to the discrimination of individual lithological units in which gabbro and granitoids for example could be identified. The newly obtained geological map then became superposed to previously done ones in order to obtain new information. Hence, results from Landsat data analyses showed clear lithological correlation between Landsat images and the available geological map in the study area. Moreover, the Kekem area is pervasively affected by a network of shear zone and fractures whose main orientation is W-E. Also, the geometry of the Kekem plutonic complex as well as its lithological association has been improved, especially its relationship with the shear zone. This shed a light on possible tectonic context of the placement of the Kekem pan-African plutonic complex.
Keywords
Geological mapping; Remote sensing; Kekem