Abstract:
Broadband magnetotelluric investigations were carried out along NW-SE profile from Potuluru to Anjanpalli
in the NE part of Cuddapah basin. The 84 km profile is adjacent to the Eastern Ghat Mobile Belt (EGMB) and Eastern
Dharwar Craton (EDC), India. Sixteen stations were established with a station interval of 2 to 7 km. The time series data
were processed with single site and remote reference approach to derive robust MT transfer functions. Regional strike
analyses indicate that the majority of the MT data is consistent with the assumption of a 2-D geo-electric strike direction,
which is N40°E. Both transverse electric and transverse magnetic mode data were inverted using 2-D non-linear conjugate
gradient algorithm. A conductive (40-300 Ohm.m) zone C1 is identified with 350 m to 2000 m thick sediment representing
Palnad sub basin (PSB). The low resistivity could be due to presence of base metals (Cu, Pb, Zn) within the Banaganapalli
quartzites and Narji limestone. The two-dimensional geo-electric model derived demarcated a moderately low resistive
feature (450 Ωm - 800 Ωm) C2 dipping southeast in the centre of the profile. The moderately conductive nature of C2
could be due to the presence of Palnad sub-basin sediments entrapped along the fault zone. The feature of C2
coincides
with Nallamalai Fold Belt (NFB). The dipping resistive crustal layer in the NE parts of Cuddapah basin suggest E-W
compression along the eastern margin during the Neoarchaean-Neoproterozoic (~2700 Ma – 970 Ma) tectonic convergence
between India and east Antarctica.
