Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

D. Atchuta Rao ¹, Ch. Rama Rao ¹, D. S. Bhaskara Rao ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad-500007, IN

Abstract

Interpretation of the total intensity aeromagnetic anomaly data and the residual gravity data of the pericratonic Mahanadi coastal basin, situated in the east coast of India has brought out NW-SE trending dislocations cutting across these basins and extending into the shelf area. This structure may be inferred as the possible extension of the NW-SE trending intracratonic Mahanadi rift. Depth estimates on the regional aeromagnetic anomalies have brought out a deep-seated sub-basement magnetic marker horizon at depths of 5-6 km in the inferred rift zone and it rises to around 2 km on either side in the onshore region. The trends in the residual gravity map around Cuttack suggests a tectonic environment possibly related to the location of triple junction at this point. This zone lies between shot points SF60 and SP70 of the Konark-Mukundpur DSS profile where it is reported that the energy has been heavily attenuated (at near distances) leading to large jumps in travel time. This zone of anomalous behaviour coincides with the inferred triple junction and calls for further detailed studies.

Keywords

Geophysics, Aeromagnetics and Gravity, Mahanadi Rift, Lambert Rift, East Antarctica.

Full Text

     

D. S. Bhaskara Rao ¹, Ch. Rama Rao ¹, D. Atchuta Rao ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

The statistical structure of the aeromagnetic anomaly field over an area of approximately 30,000 sq. km of parts of eastern Dharwar craton and the western parts of Cuddapah basin has been studied. The distribution of statistical moments of aeromagnetic field showed two magnetically different zones, viz., one towards north of 14°45'N Lat., and the other to the south of it. Directional filtering operations over the exposed granite-greenstone terrain and the adjoining intracratonic Cuddapah basin has clearly brought out an ENE to E-W trending long linear possibly related to a deep seated tectonic feature. This mega lineament separates this part of the crust into two zones of different magnetic character. Filtering operation over the aeromagnetic data applying sequential trend suppression in E-W, NW-SE and ENE-WSW directions has clearly brought out magnetic trends striking nearly N-S. These nearly N-S trends may reflect the structures that controlled the development of greenstone belts or the structures resulted during the E-W compressional event.

Keywords

Aeromagnetics, Structure, Granite-Greenstone Terrain, Cuddapah Basin, Eastern Dharwar Craton.

Full Text