Application of high resolution airborne geophysical data in geological modelling of Mohar Cauldron Complex, Bundelkhand Massif, central India: implications for uranium exploration

• Published in: Exploration geophysics (Melbourne) Vol. 45; no. 2; pp. 134 - 146
• Main Authors: Markandeyulu, A., Chaturvedi, A. K., Raju, B. V. S. N., Parihar, P. S., Miller, Roger, Gooch, Glenn
• Format: Journal Article
• Language: English
• Published: 01.06.2014
• Subjects: India, Madhya Pradesh, Bundelkhand; France, Massif Central; India, Madhya Pradesh
• ISSN: 0812-3985; 1834-7533
• DOI: 10.1071/EG12053

The Mohar cauldron, located near Mohar village, Shivpuri District, Madhya Pradesh, India, represents an explosive felsic volcanic event. The Mohar Cauldron Complex (MCC) is an important target area for uranium exploration as collapse breccias associated with extensional tectonics are traditionally important for multi-metal deposits, including uranium. Advanced processing and interpretation of the high resolution airborne electromagnetic (AEM), magnetic and radiometric data acquired over the Mohar cauldron and the surrounding environs by Fugro Airborne surveys, successfully mapped the major geological domains in the area based on their distinct geophysical characteristics. Interpretation of the data indicated the presence of three felsic intrusive bodies, only one of which, the MCC, reached the surface and collapsed. Variation in the geophysical characteristics of the three bodies is attributed to variations in hydrothermal alteration. Magnetic signature and radiometric response of the MCC and surrounding area also show signs of intense alteration. AEM data has allowed the boundary of the sediments within the MCC to be mapped accurately, along with the surrounding brecciated zone. Conductivity depth imaging calculated to a depth of 500 m clearly indicated the geometry and disposition of different layers of MCC. 3D voxel modelling of the MCC also allowed for the identification of the different lithologies that constitute the cauldron structure. 3D conductivity isosurfaces provided a thorough understanding of the subsurface distribution of conductivities.