Abstract

This study presents a comparative basin analysis of the Kerala and Mannar sub-basins located along the southwestern and southeastern continental margin of India respectively, emphasizing their structural evolution, sedimentary architecture and rift tectonic development. As integral components of the broader Cauvery-Kerala-Konkan offshore system, both sub-basins record the imprint of complex geodynamic processes associated with the breakup of Gondwana and the subsequent drift of the Indian plate. Integrated analysis of seismic and well data reveals that, although both basins exhibit signatures of passive margin evolution, their tectonostratigraphic trajectories diverge significantly due to contrasting extensional regimes and magmatic activity during rifting phases. Key stratigraphic markers K-T Boundary and Basement were marked in the Kerala and Mannar sub-basins. Subsequently, Time structure and Relief maps were prepared for these major horizons, along with conceptual Gross Depositional Environment (GDE) map for the Mesozoic sequence. The Kerala sub-basin is characterized by NE-SW oriented fault systems, thick clastic sedimentation and multiple subsidence phases, indicative of episodic rifting since the Late Jurassic. In contrast, the Mannar sub-basin displays a relatively stable structural configuration, with well-defined rift structures and a dominant marine syn-rift to post-rift depositional history. Variations in sediment accumulation, subsidence patterns and basin-fill styles between the two basins underscore the influence of local tectonic controls on rift basin evolution. These findings contribute to a deeper understanding of passive margin development in the Indian offshore and hold important implications for hydrocarbon prospectivity and regional basin modeling frameworks.