ANALYSIS OF AEROMAGNETIC DATA OVER MUTUM ... - RJEAS

Research Journal in Engineering and Applied Sciences (ISSN: 2276-8467) 1(2):142-148Analysis of Aeromagnetic Data Over Mutum-Biyu and Environs, North–Eastern, Nigeriapotential field using power spectra requires a realisticassumption of the statistical properties of the sourcedistributions (Stefan et al. 1996). The Benue Valley,which lies in the Eastern part of the study area, is alinear rift system whose development is closelyassociated with the separation of Africa from SouthAmerica and the opening of the South Atlantic Oceanduring the Cretaceous (Benkhelil, 1988). The studyarea also consists of Precambrian basement andsedimentary rocks. The basement complexes aremainly gneiss-migmatites complex, granitoids andtertiary to recent volcanic rocks basically basalts,trachytes and rhyolite belonging to Cameroonvolcanic line. On the other hand, the sedimentaryrocks consist of Pindiga formation, which is a marineshale, limestone and siltstone, Yolde formation whichis a variable sequence of sandy clay, calcareous sandstone and shelly limestone underlying by felspathicBima sandstone. Through geological and geophysicalstudies the depth to magnetic source bodies,delineation of lineaments which could host secondarymineralization, the general structural patterns and aswell as their hydrogeological implications will beprovided. This information will in turn help for abetter understanding of geology of the area.Geology of the Study AreaThe geology is made up of the Precambrian basementcomplex rocks, which are considered to beundifferentiated basement mainly gneiss-migmatitescomplex, remnants of metasediments and OlderGranite series the granitoids, Figure.1. The basementcomplex rocks mineralogically consist of quartz,feldspars biotite, hornblende, diorite and granodiorite.These rocks Outcrop at Jalingo, Kam, Gurumpawa,Kiri, Monkin and Tola. The Cretaceous sedimentaryrocks which include rocks of Pindiga, Yoldeformation and Bima sandstone outcrops to the westaround Gidan Shanu, Amar, Bangule, Gassol, Bantajiand Wuriu, with Tertiary –Recent Volcanic rockswhich consist of basalts, trachyte and rhyolitebelonging to Cameroon volcanic line outcropping atAngwam.The Bima Sandstone which overlies the basementcomplex at the base of sedimentary succession wasderived from granitic rocks (Offodile, 1977). Thelower beds of the formation are invariably felspathic.The Yolde Formation is a variable sequence ofcalcareous sandstone and shale which marks thetransition from continental to marine sedimentation.Pindiga Formation is a sequence of Marine shale witha number of limestone beds toward the base of theFormation. The Tertiary- Recent volcanic rocks in thestudy area consist of the basalts, trachyte, rhyolite,and newer basalts of eastern arm of Cameroonvolcanic line (Fig.1).Fig.1. Geological map of study area (After GSN2006)Preliminary Field WorkThe preliminary field work undertaken in this studyarea reveals some geological features and formations.These features include fractures, mineralization andjoint, and the areas include Monkin, Jalingo, MutumBiyu and Bantaji. The rock types at Monkin andJalingo are predominantly medium-grained granitewith some quartz vein mineralization which consistsmainly of quartz, feldspars, biotite and hornblendes.The quartz vein is of 20cm thickness and the fracturewith approximate lengths of 70m and 120mrespectively, are observed in the medium graingranite of Monkin area on Latitude 8 o 51ʹ 40.5"N andLongitude 11 o 41ʹ 51.5" E, at an elevation of515.3m.The mineralized vein trend NW-SE andfracture trend NE-SW, plate 1a &b. The trendscoincide with the results from lineaments/fracture onresidual magnetic data expressed by azimuthdiagram.N0 10 cmPlate.1a Quarz vein in medium grain granites atMonkin area143