Lithospheric structure and geodynamical evolution of the Laxmi Ridge: new inferences from satellite gravity studies

• Published in: Geo-marine letters Vol. 42; no. 3
• Main Author: Vasanthi, A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2022; Springer Nature B.V
• Subjects: Asthenosphere; Earth and Environmental Science; Earth crust; Earth Sciences; Evolution; Finite element analysis; Finite element method; Geology; Gravitational fields; Gravity anomalies; Gravity field; Lithosphere; Marine & Freshwater Sciences; Moho; Ocean models; Oceanic crust; Oceanography; Regions; Satellites; Tectonics; Topography; Laxmi Ridge; Panikkar and Palitana Ridge; Crustal and mantle architecture; Arabian Sea; Finite Element Method; Satellite gravity field
• ISSN: 0276-0460; 1432-1157
• DOI: 10.1007/s00367-022-00737-8

The tectonic evolution and the nature of the Earth’s crust beneath the Laxmi Ridge, located in the northern part of the Arabian Sea, have been a subject of considerable debate for a long time. Existing geodynamic models show signs of both continental and oceanic type crust beneath this ridge. In the present study, high-resolution satellite gravity field over the Laxmi Ridge and its adjoining areas has been analysed to address this incongruity. The study presents a deep sub-surface crustal and lithospheric density model across this region using residual gravity anomalies, computed by the finite element method, which clearly demarcates the boundaries of various prominent crustal-scale geotectonic features. Based on the extent of positive gravity field, it is inferred that the Palitana Ridge may be an extension of Panikkar Ridge, which is much wider (150–200 km) than hitherto known. The 2½D residual gravity modelling carried out across the Laxmi Ridge and adjacent Laxmi Basin reveals depth to the Moho beneath this ridge around 9–10 km, which is underplated by about 10-km-thick differentiated magmatic layer below the Moho, thereby supporting its oceanic affinity. The lithosphere–asthenosphere boundary (LAB) beneath the Laxmi Ridge is estimated to be at a shallow depth of about 50 km, which deepens down to 75 km on either side.