Interpretation of Aeromagnetic Data of Panna and Adjoining Area, Parts of M.P. & U.P., for Evaluation of Structural Patterns Favourable for Emplacement of Kimberlite Clan of Rocks and Estimation of Depths of Magnetic Bodies

The rocks of Vindhyan Supergroup overlying Bundelkhand Granites host the diamondiferous Kimberlite diatremes in Kaimur Group and diamondiferous conglomerates within the Rewa Group. This region, collectively referred as the 'Panna Diamond Belt' was flown by the Geological Survey of India aircraft during the years 2001-2002 and the aeromagnetic data generated are interpreted here. The survey was carried out at an altitude of 150 m above ground level with traverse spacing of 500 m.

The International Geomagnetic Reference Field (IGRF) corrected aeromagnetic data was brought to a plane at 600 m above msl and was subjected to terrain correction. Interpretation of this area yielded several structural trends in NE-SW, ENE-WSW, nearly E-W, nearly N-S and NW-SE directions in the form of magnetic discontinuities and linears, which are indicative of structural patterns like formational contacts/faults/fractures and body axes. The study area is characterized by a strong magnetic linear feature trending in ENE-WSW direction with intersections in nearly N-S direction representing transverse faults at some places and also intersected by two prominent features on either side, one around Majhagaon and the other towards north of Usrar. This prominent ENE-WSW trending magnetic feature is seen to fall along the contact of Vindhyan Supergroup with the adjacent Bundelkhand Granite Complex (BGC) and strong magnetic closures along this feature represent the intrusive activity at depth. In the northern part of the area occupied by BGC. Prominent magnetic features are obtained in the direction of NE-SW and few in N-S and E-W directions represent the fracture system.

The quantitative interpretation of aeromagnetic data employing radial power spectrum, matched filtering, 2-D, 3-D and contact modeling indicated the depths of causative sources. The radial power spectrum indicated three magnetic interfaces at 380 m, 1.3 km and 5.3 km from the plane of observation. The results of 2-D modeling of terrain corrected aeromagnetic data along Panna Diamond Belt yielded the depth range of 410 m-690 m from the observation plane correlatable with the interface at 380 m. The matched filtered map of second layer indicated the continuation of these magnetic bodies. The results of 3-D prism modeling of Reduced to Pole (RTP) data along Panna Diamond Belt indicated the depths in the range of 0.9 km-1.7 km from the observation plane, which is correlatable with the interface at 1.3 km. The matched filtered map of deep layer indicated that all the magnetic closures along Panna Diamond belt disappeared except a huge magnetic closure around Majhagaon-Hinota area. This appears to be a deep intrusive body and manifested in the form of different magnetic bodies at shallower depths. The depths of major NE-SW trending magnetic features in the northern part over BGC are of deeper nature. A few potential blocks were identified for search of possible emplacement of Kimberlite Clan of Rocks (KCRs).