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

R. K. Verma ¹, M. Mukhopadhyay ¹, P. B. V. Subba Rao ¹, Y. Satyanarayana ¹

Affiliations
1 Indian School of Mines, Dhanbad, IN

Abstract

A regional gravity survey has been carried out over the area lying between latitude 20°30' to 21°30'N, and longitude 85° to 86°15'E, forming a part of south Singhbhum geological province and northern part of the Eastern Ghats. The area is well-known for Sukinda ultramafic complex, Diateri and Malayagiri iron-ore deposits as well as Sukinda thrust.

Nearly 350 gravity stations were established along main roads, forest roads and cart tracks. Bouguer anomaly map of the area shows gravity highs over the Diated iron-ore group, the Malayagiri volcanics, the Sukinda ultramafic complex as well as over the Eastern Ghats province. Two-dimensional models. have been prepared to show the nature of the ultramafic complex, iron-ore group (lOG) of rocks and the Sukinda thrust. The lOG appear to form narrow but steeply dipping sedimentary troughs, while the Sukinda thrust appears to be steeply dipping to the south.

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G. R. K. Murty ¹, Y. Satyanarayana ¹, T. Pradeep Kumar ¹

Affiliations
1 Naval Physical and Oceanographic Laboratory, Thrikkakara, Cochin-682021, IN

Abstract

A study of the spectral analysis and two-dimensional modelling of magnetic data collected along the track of 200 km traversing the southern part of the Gulf of Mannar indicates the presence of an anomalous body within the basement. The total field magnetic anomaly along the track is well explained by variations in the topogrphy of the anomalous body of normal polarity and uniform magnetisation. The model shows a topographic relief of about 6 km. The presence of volcanic vents in this area suggests that the anomalous body could be more basic in nature having high susceptibilty values.

Keywords

Geophysics, Gulf of Mannar, Magnetic Data.

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Y. Satyanarayana ¹, G. R. K. Murty ¹, Chanchal De ¹

Affiliations
1 Naval Physical and Oceanographic Laboratory, Thrikkakara, BMC (PO), Cochin-682021, IN

Abstract

Laccadive ridge is a prominent feature in Indian Ocean, off west coast of India .Marine magnetic survey carried out across the ridge between 8° and 12°N reveals that the ridge is associated with strong magnetic anomalies of the order of 200 to 400 nT. A significant low magnetic trend is present over the topographic high of the ridge. The results of spectral analysis and two-dimensional modelling of the data suggest the possible presence of an anomalous basic body, with varying thickness. The inclination and declination obtained indicate that the basic body may be derived from same volcanic activity as of the onshore traps associated with normal remanent magnetism.

Keywords

Geophysics, Magnetic Data, 2-D Modelling, Laccadive Ridge.

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