Magnetometric delineation of sub-basins, understanding their allochthonous/autochthonous origin in the basin development - A case study from Proterozoic Cuddapah Basin, India

Abstract Cuddapah basin, situated in the southeastern part of India, is a major Proterozoic basin formed as an amalgamation of five sub-basins with fold and thrust belts located in its eastern part. Many researchers opined that these fold and thrust belts were formed in the collision process of the Prince Charles Mountains-Rayner complex of Antarctica with this part of south India during the formation of the Rodinia Supercontinent. Amalgamations involved significant tectonic events that caused temporal changes in the structural patterns of fold and thrust belts. Debates are widespread on whether the Nallamalai Fold Belt (NFB) is a part of Antarctica that got accreted to the Indian shield. The Qualitative appraisal of the aeromagnetic data revealed that Total Magnetic Intensity (TMI) anomaly distribution is constrained by basement configuration within various sub-basins, which in turn is controlled by newly inferred faults systems. Probable block rotation events related to the compressional tectonics (that acted during collisional events) caused the present shape of the basin's eastern margin, which is parallel to the continental rift margin of India at this location. From the interpretation of aeromagnetic data, we identified substantial clues on the rotation of the northern and southern halves of the NFB to develop a possible model of tectonic development of the Cuddapah basin (and its sub-basins). Our inferences suggest that NFB was always a part of the Cuddapah basin. The proposed tectonic model establishes the interlink between the NFB and western sub-basins throughout the evolution of the Cuddapah basin. Modeling results of magnetic data indicate geophysical evidence of significant thrusting along the western margin of the NFB.