Using Ground Magnetics to Detect Limestone in Masvingo, Zimbabwe

Ground magnetic geophysical survey techniques were successfully applied to detect near-surface limestone deposits in karstic terrain of the Nyanda Mountains in Masvingo, Zimbabwe. The broad aim was to establish the geomagnetic total field anomaly maps that reveal the metamorphic and sedimentary units in the study area thereby identifying limestone reserves crucially required for mostly cement production. The results from the mountain range surveyed confirmed that buried limestone units existed within an undulating karstic topography which correlated perfectly well the reconnaissance and geological mapping in exposed areas. Limestone, being non-magnetic was characterized by low values in the surveyed area. Ground magnetic survey was preferred not only because of its cost effectiveness but also that compared to alternative ground penetrating radar and resistivity methods often used in limestone exploration; it is very convenient in the otherwise difficult terrain. The results produced very encouraging and usable clearly delineated maps.