APPLICATION OF REMOTE SENSING IN MAPPING GEOLOGICAL STRUCTURES WITHIN OKE-ONIGBIN AREA, SOUTHWESTERN NIGERIA

Abstract

Advancement of digital image processing (DIP) and availablility of multispectral remote sensing data have greatly aided structural geological mapping and mineral exploration. Structural mapping of Oke-Onigbin area was carried out using combined detailed field mapping and satellite image processing techniques. Shuttle Radar Topographic Mission (SRTM), Landsat 8 (OLI) and Sentinel were acquired and processed using Erdas Imagine TM, ArcGIS 10.3 and ILWIS 3.8 TM softwares. Automatic extraction method was employed for lineament extraction using PCI Geomatica software. Geological, lineament and structural maps were produced using field and remote sensing data. Delineated lithologies underlying the study area are migmatitic biotite gneiss, granitic gneiss, pelitic schist, amphibolites, marble quartzites, granodiorite, granite and pegmatite. 70, 1127 and 1380 were extracted respectively from SRTM, Landsat 8 and Sentinel, showing two (200and 100), three (300, 100 and 300) and three (300, 100 and 300) main orientation directions respectively. Results indicate that most of the lineaments trend in the NNE-SSW direction, while others trend in the N-S, NE-SW, WNW-ESE and E-W orientations. The histogram indicated a bimodal distribution for SRTM, and polymodal distribution for Landsat 8 and Sentinel. Quartzite has the highest lineament concentration while granite has the least concentration. Deformation in the area resulted into development of both ductile structures (tight to isoclinals folds, recumbent fold, open to close folds and kinked bands) and accompanying brittle structures (reverse, normal and strike slip faults). The mapped structures are grouped as S1-S3 foliations, F1-F4 folds, and D1-D4 deformations. Observation of the major structural trend on the field mapping corresponds to the lineaments extracted from remote sensing techniques. The area shows high mineralization potential for precious metals, gemstones and industrial minerals Mineralization potential map was produced from integration of the already produced maps.