World Rural Observations 2011, 3(1) http://www.sciencepub.net/rural 1 Identification of Linear Features using continuation Filters Over Koton Karifi area, Nigeria, From Aeromagnetic Data. Abdulsalam N. Nasir. 1 , Mallam Abu. 2 Likkason K. Othniel. 3 1 & 2 Department of Physics, University of Abuja, Gwagwalada, FCT PMB117, Nigeria 3 Physics Programme, Abubakar Tafawa Balewa University, Bauchi State, PMB0248, Nigeria nasnaeem@yahoo.com Abstract: Magnetic lineaments over sedimentary basins are zones of gradient interruptions or zones marked by sharp changes of the style of anomalies. These anomalies might be due to the fault affecting the underlying basement alone or both the basement and the sedimentary formations. In this paper, we have applied continuation filters (upward and downward continuations) as processing tools to the aeromagnetic total-field intensity anomaly of the koton-karifi area, Nigeria. The results from these field continuations revealed that as the upward continuation increases the field become broader. The general indication of this is that the linear feature (fault or fracture) might have been hosted in the basement structure and is significant as it was likely an earlier emplaced feature before SE Santonian movements took place . Not much deduction could be drawn from the result of downward continuation as it was generally observed that as we continued the field below source level the contours become clumsy and full of noise. [Abdulsalam N. Nasir., Mallam Abu. Likkason K. Othniel. Identification of Linear Features using continuation Filters Over Koton Karifi area, Nigeria, From Aeromagnetic Data. World Rural Observations 2011;3(1):1-8]; ISSN: 1944-6543 (Print); ISSN: 1944-6551 (Online). http://www.sciencepub.net/rural. Keywords: upward continuation, downward continuation, fault, and fracture. 1. Introduction The aim of a magnetic survey is to investigate subsurface geology on the basis of magnetic anomalies in the Earth’s magnetic field resulting from the magnetic properties of the underlying rocks. Magnetic surveys can be performed on land, at sea and in air. The speed of operation and cost make airborne magnetic surveys very attractive, where the principal objective has been to assist in mineral and groundwater development through improved geologic mapping. In addition, aeromagnetic surveys have traditionally been applied at the early stage of petroleum exploration to determine depth and major structure of crystalline basement rocks underlying sedimentary basins. The methodology for acquiring and compiling data appears to be keeping pace with modern technology so that presently the magnetic method is by far the most widely used of all geophysical survey; both in terms of line-kilometres surveyed annually and in total line-kilometres (Paterson and Reeves, 1985). Thus compared to other geophysical methods, the aeromagnetic data are always readily available and so it is important to exploit the potentialities of these data. This has been the aim of this work. This paper focuses on the analyis of a total-field aeromagnetic data using continuation to the field (upward and downward continuations) over the Koton Karifi area, central Nigeria. The outcome of the analysis is expected to throw more light on the geology and other linear features of the area. Fig. 1.1 Geological map of Nigeria, 1 = Cretaceous- Recent sediments; 2=Younger Granites; 3 = Older Granites; 4 = Undifferentiated Metasediments; 5 = quartzite and quartzite schist; 6 = Undifferentiated basement complex and 7 = Tertiary volcanics (From Geological map of Nigeria 1994: compiled by the Geological Survey of Nigeria). Inset is the study area: the Koton Karifi Area of the Nupe Basin, Nigeria