Crustal structure along the Kerala-Konkan Basin, southwest continental margin of India, using multi-channel seismic and gravity modelling: Implications on India-Madagascar rifting and basin evolution

• Published in: Journal of Asian earth sciences 2023-02, Vol.242, p.105504, Article 105504
• Main Authors: Unnikrishnan, P., Gilbert, M.G., Radhakrishna, M.
• Format: Article
• Language: English
• Subjects: Gravity; Kerala-Konkan Basin; Lithosphere thermal gravity; Magnetic; Stretching factors; Western Continental Margin of India
• ISSN: 1367-9120; 1878-5786
• DOI: 10.1016/j.jseaes.2022.105504

•Moho map and stretching factors reveal extended continental crust below K-K basin.•The continent-ocean boundary is located to the west of Laccadive Ridge.•TWT maps show the presence of thick sediments along coast parallel grabens.•Konkan and Laccadive basins formed by rifting between Laccadive Ridge and India. The Western Continental Margin of India (WCMI) is a magma-rich margin that formed during the separation of India-Seychelles block from Madagascar in Mid Cretaceous, and separation of Seychelles from India in the Late Cretaceous. We present here an integrated interpretation of geophysical data pertaining to the Kerala-Konkan (K-K) Basin belonging to the southern part of WCMI to delineate the structure, sedimentation and the basin evolution. The multi-channel seismic (MCS) reflection data along with a few drilled wells revealed three regionally continuous sequence boundaries with thick sediments confining to coast-parallel grabens. The residual crustal Bouguer anomalies, computed after removing the gravity effects of water, sediments and the lithosphere thermal structure from the free-air anomalies, are used to prepare the Moho depth map which shows Moho ranging from 13 km in the oceanic domain, 25 km in the Laccadive Ridge and about 36–48 km below the Indian shield crust. The computed stretching factors (β-values) and the Moho depths together reveal the presence of thinned continental crust below K-K Basin with the Continent-Ocean Boundary located west of Laccadive Ridge. The 2-D joint potential field modelling revealed the crustal architecture which strongly indicate that the eastern basin (Kerala Basin, including Laccadive Basin and Konkan Basin together) had formed during the Late Cretaceous rifting between the Laccadive Ridge and the Indian mainland subsequent to the separation of Madagascar from India at 88 Ma.