Precambrian mega lineaments across the Indian sub-continent – preliminary evidence from offshore magnetic data

• Published in: Current science (Bangalore) Vol. 90; no. 4; pp. 578 - 581
• Main Authors: Subrahmanyam, V., Subrahmanyam, A. S., Murthy, K. S. R., Murty, G. P. S., Sarma, K. V. L. N. S., Rani, P. Suneeta, Anuradha, A.
• Format: Journal Article
• Language: English
• Published: Current Science Association 25-02-2006
• Subjects: Continental shelves; Continents; Earthquakes; Magnetic anomalies; Marine; Oceanography; RESEARCH COMMUNICATIONS; Shear zones; Tectonics; Water depth; ISW, India
• ISSN: 0011-3891

Marine and airborne magnetic data over south Indian continent including the western and eastern continental margins between latitudes 12°30′N and 10°N were studied and interpreted. The total intensity magnetic anomalies over the south Indian continental block between 10°45′N and 12°30′N exhibit distinct character compared to the adjoining northern and southern blocks. The study revealed the presence of two Precambrian mega lineaments over a stretch of 750–800 km running in east-west direction. They were mapped approximately from the isobath of 1500 m in the western continental margin, across the south Indian Peninsula and through the eastern continental margin up to a water depth more than 3000 m. These mega lineaments may be acting as a crustal junction/contact between two major geological provinces, viz. the Southern Granulite Terrain (SGT) and the Dharwar Craton. In addition to these two mega lineaments, major faults have been inferred, which acted as controlling parameters to create a bulge/bite in the coastline off Cuddalore. The continent–ocean boundary/transition on the Eastern Continental Margin of India (ECMI) may be the offshore boundary for these two Precambrian mega lineaments.