Gravity and magnetic surveys for kimberlite structures in Baghain and Rampura-Motwa, Panna Diamond Belt, Madhya Pradesh, India

In order to delineate the kimberlite bodies, gravity and magnetic surveys were undertaken in the Panna Diamond Belt, Madhya Pradesh, in Central Indian Diamond Province. The Panna Diamond Belt lies in the Baghain formations of Kaimur and Rewa group of rocks. The Bouguer anomaly map was based on a total of 259 gravity observations and the total intensity magnetic map was prepared based on 230 magnetic observations in Baghain and Kirwa in the Kaimur group of rocks, and Kitha and Rampura-Motwa regions in the Rewa group of rocks, both groups of rocks form part of the Vindhyan Super Group in the Panna Diamond Belt. The Bouguer gravity maps indicated a high gravity, while the magnetic maps indicated a bipolar nature of anomalies in this area. The Rampura-Motwa area also depicted a significant circular anomaly both in the gravity and magnetic maps in the south western region which belong to the Rewa group of rocks. The spectral density maps and Euler solutions for depth estimation of the probable kimberlitic pipes indicated depths between 60 and 120 m in the surveyed areas. These depths are well correlated with the recent discoveries as provided by drill logs (80 to 150 m depth) of the kimberlites in the Baghain sandstone formations of Kaimur and Rewa group of rocks. The present paper presents some of the probable kimberlitic pipes in this region, which had not been ascertained earlier. The modelled data allow us to confidently interpret the gravity and magnetic response and justify the use of these geophysical methods as successful tools for the exploration of kimberlite pipes in the area.