Bouguer Gravity Modelling of Central Cuddapah Basin

Bouguer gravity data over a large central part of the Cuddapah basin have been obtained by digitising the 5-mGal contour map. The regional and residual components have been separated by a newly developed finite element scheme, contoured with colour scale and residual anomalies are modelled for the basement structure in several profiles. The data is thereby rendered more attractive and easily visualised. The thickness of the sediments derived by gravity modelling has been compared with that along two deep seismic sounding (DSS) profiles. The thick columns(˜ 9 km) of sedimentary formations in the Proterozoic Cuddapah basin are likely to interest the organizations dealing with hydrocarbon exploration.

An interesting relationship has been brought out among the three mantle-Derived rocks, i.e. the volcanics of the western margin, the kimberlite emplacement and the dyke swarms. These three features seem to share a common gravity field.

Based on the correspondence between the locations of kimberlite pipes and lamproites and the regional gravity anomalies we suggest the kimberlites and the lamproites to occur along two concentric rings with the centre lying approximately in the southwest region of the Cuddapah basin. Further, the occurrences of kimberlite pipes and lamproites at Vijayawada and Ramannapet on northeast, Narayanpet on the west and Kalyandurg on the southwest led to suggest a third ring. In fact, three new kimberlite pipes have been reported at Siddanpalli between Gadwal and Raichur that lie on the third ring. The gravity studies also indicate the Cuddapah Front on the east to form a possible collision boundary.