2-D INVERSION OF GEOMAGNETIC DEEP-SOUNDING DATA NEAR UJJAIN-GUNA, INDIA

The inductive response of a hypothesized conductor located between Ujj ain and Guna, India, has been modelled. In the absence of a satisfacto ry fit from forward numerical modelling, 2-D inversion of the anomaly profile of Z/H ratio has revealed the main conductor to be situated be low Ujjain-Guna with an offset and another secondary conductor in the form of a jointed body. The main conductor is at a depth of 23 km from the surface, thickness being 20 km and the resistivity 3 OMEGAm. The jointed secondary conductors are at depths of 31 km and 28 km with thi cknesses of 14 km and 21 km and resistivities 3 OMEGAm and 5 OMEGAm re spectively. The resistivity contrast with the background is a factor o f 1600 or even slightly more. The possibility of mineralization on the flanks of the subsurface granitic intrusion cannot be ruled out. Howe ver, partial melting of the subsurface granites seems to be another pl ausible explanation for the high conductivity contrast.