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

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Evaluation of Aeromagnetic Data and Regional Geological Interpretation for a Part of the Cuddapah Basin


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1 Airborne Mineral Surveys and Exploration Wing, Geological Survey of India, No.2, Church Street, Bangalore 560001, India
     

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Based on total intensity aeromagnetic profile data across the Cuddapah Basin, it is possible to distinguish the Cumbum and Bairenkonda Formations of Nallamalai Group. Further subdivision within individual intercalated dolomites and quartzites of Cumbum Formation is also found feasible. This discriminatory criterion can be used to guide mineral exploration, especially in the dolomites of Cumbum Formation. The magnetic variations along the strike of the Cumbum Formation is considered to be due to minor undulations in basin geometry, ref1ecting palaeogeography of pre-Cumbum period. The high magnetic response in Tadpatri and Vempalli Formations is mostly due to their association with basic volcanism.

All along the eastern margin of the basin, there is an ascending magnetic trend which coincides with a thrust. The geometry of Iswarakuppam dome is inferred to be asymmetric and with a tilt towards cast and/or controlled by a crustal fracture. The relative high magnetic response and discordant trend over Kurnool Group of rocks in the western part of the Kunderu Basin is attributed to the occurrence of the basement at shallow levels locally. Regional and areal trend surfaces have been estimated and causative magnetic responses due to basement and overlying metasediments are evaluated. For trend surface analysis, window sizes have been determined and computerization is suggested. From the LANDSAT imagery interpretation, a three stage basin evolutionary trend has been inferred.

A northwest-southeast tectonic break near Cumbum town is proposed, along which the basin oscillated, causing shallowing of the basin to the north and deepening to the south. Further, it is postulated that the northern and southern blocks tilted to east and west respectively moving on a northeast-southwest axis, resulting in the basement rise in the northwest and southeastern parts and gentle slope in the northeastern and southwestern parts in the area of study.


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  • Evaluation of Aeromagnetic Data and Regional Geological Interpretation for a Part of the Cuddapah Basin

Abstract Views: 190  |  PDF Views: 4

Authors

M. V. Ramanamurthy
Airborne Mineral Surveys and Exploration Wing, Geological Survey of India, No.2, Church Street, Bangalore 560001, India
U. S. N. Reddy
Airborne Mineral Surveys and Exploration Wing, Geological Survey of India, No.2, Church Street, Bangalore 560001, India

Abstract


Based on total intensity aeromagnetic profile data across the Cuddapah Basin, it is possible to distinguish the Cumbum and Bairenkonda Formations of Nallamalai Group. Further subdivision within individual intercalated dolomites and quartzites of Cumbum Formation is also found feasible. This discriminatory criterion can be used to guide mineral exploration, especially in the dolomites of Cumbum Formation. The magnetic variations along the strike of the Cumbum Formation is considered to be due to minor undulations in basin geometry, ref1ecting palaeogeography of pre-Cumbum period. The high magnetic response in Tadpatri and Vempalli Formations is mostly due to their association with basic volcanism.

All along the eastern margin of the basin, there is an ascending magnetic trend which coincides with a thrust. The geometry of Iswarakuppam dome is inferred to be asymmetric and with a tilt towards cast and/or controlled by a crustal fracture. The relative high magnetic response and discordant trend over Kurnool Group of rocks in the western part of the Kunderu Basin is attributed to the occurrence of the basement at shallow levels locally. Regional and areal trend surfaces have been estimated and causative magnetic responses due to basement and overlying metasediments are evaluated. For trend surface analysis, window sizes have been determined and computerization is suggested. From the LANDSAT imagery interpretation, a three stage basin evolutionary trend has been inferred.

A northwest-southeast tectonic break near Cumbum town is proposed, along which the basin oscillated, causing shallowing of the basin to the north and deepening to the south. Further, it is postulated that the northern and southern blocks tilted to east and west respectively moving on a northeast-southwest axis, resulting in the basement rise in the northwest and southeastern parts and gentle slope in the northeastern and southwestern parts in the area of study.