The magnetic gradient tensor (MGT) provides gradient components of potential fields with mathematical properties which allow processing techniques e.g. analytic signal techniques. With MGT emerging as a new tool for geophysical exploration, the mathematical modelling of gradient tensor fields is necessary for interpretation of magnetic field measurements. The point-dipole and line of dipoles are used to approximate various magnetic objects. I investigate the maxima of the magnitude of magnetic vector components (MMVC) and analytic signals of magnetic gradient tensor (ASMGT) resulting from point-dipole and line of dipoles sources in determining horizontal locations. I also present a method in which depths of these sources are estimated from the ratio of the maximum of MMVC to the maximum of ASMGT. Theoretical examples have been carried out to test the feasibility of the method in obtaining source locations and depths. The method has been applied to the MMVC and ASMGT computed from the total field data over a basic/ultrabasic body at the emerald deposit of Socoto, Bahia, Brazil and buried water supply pipe near Jadaguda Township, India. In both field examples, the method produces good correlations with previous interpretations. (C) 2009 Elsevier B.V. All rights reserved.