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Murthy, Ch. V. V. S.
- 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
Authors
1 Geological Survey of India, GMC Division, AMSE Wing, Vasudha Bhavan, Kumaraswamy layout, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 69, No Spl Iss 3 (2007), Pagination: 653-663Abstract
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).
Keywords
Aeromagnetic, Kimberlite, Panna.- Study of Structural Pattern through Aeromagnetic Data for Mineral Prospecting and Kimberlite Clan Rocks in an Area around Mahbubnagar, A.P.
Authors
1 Geological Survey of India, GMC Division, AMSE Wing, Vasudha Bhavan, Kumaraswamy Layout, Bangalore - 560 078, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 72, No 2 (2008), Pagination: 175-189Abstract
The qualitative interpretation of aeromagnetic map of an area around Mahbubnagar, indicated several linears and discontinuities, which suggest the presence of various magnetic bodies and fractures, faults, and shears. The magnetic discontinuities trend in NW-SE, WNW-ESE, NE-SW, N-S and E-W directions. The quantitative interpretation indicated three magnetic interfaces at the depths of 4.5 km, 1.3 km and 670 m from the plane of observation at 675 m above m.s.l. The magnetic maps of different layers prepared by matched filtering have helped in understanding the structural setup. The study of these maps has indicated that major discontinuities (fractures/faults) extend to greater depths. The 2-D modelling revealed the dips of the bodies varying between 3°-27° indicating the near horizontal type of sources excepting the one with 69° dip. The depths to the top of these bodies were found to vary between 308 m-1180 m from the plane of observation. The 3-D prism modelling of selected anomalies indicated that most of them are near horizontal type of sources except a few. The depths to the top of these prism bodies vary between 440 m- 831 m and to the bottom between 682 m-7136 m from the plane of observation. This shows that majority of the magnetic bodies are emplaced in the surficial and shallow layers and few extend to greater depths. Based on this study, 15 blocks were identified as potential areas for mineral prospecting and also for possible emplacement of Kimberlite clan rocks (KCR).Keywords
Aeromagnetic, Mineral Prospecting, Mahbubnagar, Andhra Pradesh.- Analysis of Aeromagnetic Data Over Part of Bundelkhand Granite Complex for Geology and Structure
Authors
1 AMSE Wing, Geological Survey of India, Vasudha Bhavan, Kumaraswamy Layout, Bangalore - 560 078, IN