Derivatives And Analytic Signals: Improved Techniques For Lithostructural Classi fications

In this study, derivatives and Analytic Signal (AS) techniques were employed to reveal the nature of rocks and lithostructural relationships that exist within the basement complexes around Ekiti and Ondo States. The derivatives techniques were used to enhance theReduction to Equator Total Magnetic Intensity (RTE_TMI) data. In order to make the results from derivatives techniques worthwhile and robust, Analytic Signal (AS) technique was then applied. The results of the derivatives and analytic signals revealed seven different lithological suites, namely: migmatite (M), migmatite-gneiss (MGn), gneiss and granite (Gn/G), schist and quartzite schist (S/Qs), granitegneiss and charnockite (Gn/Ch), charnockite and granite (Ch/G), and granite (G). Five different major lineaments/faults, folds and lithological contacts were also identified. The lineaments/faults were classified as F1, F2, F3, F4 and F5 with NW-SE, NNE-SSW, NE-SW, E-W and NNW-SSE trends respectively. Folds were classified into S1, S2, S3, S4 and S5 as symmetrical, asymmetrical, recumbent, ptygmatic and drag folds respectively. While lithological contacts were classified into C1, C2, C3, C4 and C5 as sharp contact of migmatite and granite, migmatite and granite-gneiss/charnockite/granite, migmatite and gneiss/granite, migmatite and schist/quartzite schist, and migmatite and gneiss respectively. It is evident from the study that migmatites and gneisses which form the basement in the area have been highly deformed and evince many intrusives. A detailed geological map for the study area is proposed as deduced from results analyses.