Regional magnetic surveys in part of Delhi Fold Belt, Rajasthan (India) and implications for basement structure and mineralization

This paper presents the results of regional ground magnetic surveys carried out over an area of 4200 sq. km in parts of Ajmer and Bhilwara districts, Rajasthan, India. The study area falls in the Obvious Geological Potential (OGP) zone associated with economic mineral deposits of India. The survey was conducted for delineating the extension of various rock sequences within the Proterozoic Delhi Fold Belt (DFB). The survey brought out a strong NE-SW trending magnetic anomaly over the rocks of DFB and a mild anomaly in the northwestern part of the area, which is covered by the thick sediments of the Marwar Basin (MB) basin. The NE-SW trending anomaly in the area could be attributed to the exposed/near-surface Archaean basement that has come closer to the surface as a result of Delhi Fold Belt (DFB) tectonics. The anomaly trend brought out the clear picture of the magnetic basement within the Bhilwara Supergroup and their sub-surface structures and associated mineralization, if any. The qualitative analysis of the magnetic data delineated the contact of the significant litho units (Marwar Basin and Delhi Fold Belt). The Euler depth solutions also provided an idea about the magnetic source depths and a cluster of shallow depth solutions have been generated over the Delhi Fold Belt, which may be due to the weak susceptibility of the weathered layer. The amplitude power spectrum has been attempted for estimating the depth interfaces for each selected profile. The average depth to the basement of each profile is estimated as 1.5 km. The contacts between different litho units are also marked. The 2D modeling of a few representative profiles across the DFB reveals that the average magnetic basement depth is about 1.5 km. It is concluded that, the contact zone between Marwar Basin (MB) and Delhi Fold Belt (DFB) is structurally controlled. The results of this study has brought out significant structural features which can form favorable target areas.

Automated summary

This paper presents the results of regional ground magnetic surveys conducted in Ajmer and Bhilwara districts, Rajasthan, India, to study the geological structures. The surveys revealed a strong magnetic anomaly related to the exposed Archaean basement and the tectonics of the Delhi Fold Belt. The analysis also identified the contacts between different litho units and estimated the depth of the magnetic basement.