Aeromagnetic evidence for the arcuate shape of Mahanadi Delta, India

The stream network comprising Mahanadi and its tributaries, viz. Katjhori, Devi, Koyakhai, Kushbhadra and Bhargavi, cut transversely the ESE-WNW trending basement structure in the Cuttack-Paradip-Puri section and diverge radially from one another near and around Cuttack. The Mahanadi river flows in an ESE-WNW direction, the Katjhori and Devi rivers flow in a NW-SE direction and Koyakhai, Kushbhadra and Bhargavi River in an almost N-S direction. The general southeasterly direction of these rivers and the delta formation was thought to be continued throughout the Quaternary period and the delta was a case of superposition upon the deformational structures derived from the erosional surfaces covered by recent sediments. Analysis of the aeromagnetic anomaly field of the Mahanadi Delta area of the on-shore portion has indicated three prominent structural trends in ESE-WNW, NW-SE and N-S directions along which the rivers Mahanadi/Chitratala, Katjhori and Devi, Koyakhai, Kushbhadra and Bhargavi flow, respectively. The tectonic disturbance along the N-S direction, in the western part of Bhubaneswar-Puri section, seems to have been controlling the Koyakhai and Kushbhadra and Bhargavi river system, following the possible trace of 85 ◦ E Ridge, whereas the concealed NW-SE trending Mahanadi graben trend is inferred to be the probable cause for the NW-SE flow of the Katjhori river in the middle portion south of Cuttack and the ESE-WNW flow of the Mahanadi and Chitratala rivers in the Cuttack-Paradip section controlled by the Eastern Ghat trend.