Geophysical Exploration of Iron Ore Deposit in Kimachia Area in Meru County in Kenya, Using Gravity and Magnetic Techniques

A combined geological and geophysical survey undertaken in Kimachia area of Meru County in central Kenya has established the existence of small scale iron ore deposit that seems to be part of a more extensive iron rich zone. The study has identified magnetite as the main ore in the geological formations. Kimachia iron can be classified as a sandstone deposit. The origin of the ore has not been established but, is obviously none magmatic. It is however possible that the ore deposits, like most iron ore deposits in the world, is formed from early Archean eon to late Precambrian. The study further established that the ore grade varies from medium to high quality. Alluvial iron rich sand deposits in the valley area were the first to be identified by use of simple magnets. Gravity surveys revealed a zone of high gravity anomaly aligned in the same direction as hills on the elevated topography. Further, magnetic methods conducted along the same stations used in the gravity survey revealed several zones with high magnetic anomalies coincident with the gravity anomalies characteristic of ferromagnetic rocks some of which have been magnetized over the hilly areas. Pitting in two selected zones within the gravity and magnetic anomalies confirmed the existence of the ore bearing rocks within a few feet of the surface.