Insights from radiocarbon and OSL dating into holocene sea level variability and neotectonic activity along the Odisha coast, India

The Odisha coast on the eastern margin of India preserves a diverse suite of late Quaternary landforms that record relative sea-level (RSL) changes. This study focuses on the northern sector, where beach–dune complexes and paleo-tidal flats were investigated to reconstruct Holocene shoreline evolution. Organic matter, wood fragments, molluscan shells, and carbonaceous clays were dated using radiocarbon methods, while dune sands were analyzed by Optically Stimulated Luminescence (OSL). The chronology reveals an overall regressive coastal trend during the Holocene, interrupted by higher RSL stands between ~ 8.4 ka and ~ 7.1 ka. Shell horizons from tidal flat deposits indicate mid-Holocene transgressive phases, while OSL ages of ~ 2.4–1.7 ka from inland dune ridges indicate late reworking of aeolian sediments. In addition to eustatic controls, the study suggests localized neotectonic activity that has influenced shoreline stability and sediment preservation. These findings refine the Holocene RSL curve for the Odisha coast, demonstrate deviations from global sea-level patterns, and highlight the combined influence of climatic and tectonic processes in shaping coastal evolution. The study also contributes new chronological data to a region that has remained underrepresented in sea-level reconstructions for the eastern Indian seaboard.