Assessing sedimentological proxies for characterizing tropical storm deposits in the Chandipur coastal region of Bay of Bengal, India: A modern analog for paleotempestology

Abstract. Coastal morphodynamics in barrier systems are governed by changes in sediment supply, sea level, and storm events. However, the limited availability of well-characterized modern analogs hinders the interpretation of sediments deposited by tropical storms, particularly in the Bay of Bengal. This study aims to evaluate the sedimentological proxies for identifying overwash deposits in the back-barrier region of Chandipur, India, using integrated granulometric and morphoscopic analyses across five sediment transects. Grain size distributions were modeled into four end-members (EMs) representing aqueous suspension-dominated transport, aqueous suspension with minor saltation, aeolian saltation, and high-energy depositional environment. To address compositional constraints, centered log-ratio (Clr)-transformed EM scores, were analyzed spatially to assess variations in depositional processes. Quartz grain morphoscopy, following the Cailleux classification, was used to assign grains to seven established shape categories, with fractured C-type grains being interpreted as indicative of high-energy mechanical modification. By combining grain size and morphoscopic characteristics, cluster analysis distinguished three sediment groups linked to aqueous, aeolian, and overwash-dominated environments. Microtextural observations further refine transport interpretations, indicating that many grains underwent high-energy collisions typical of marine reworking during storm events. A multi-proxy approach incorporating EM modelling, compositional analysis, grain morphology, and microtextural evidence establishes a reliable framework for differentiating overwash deposits. The results emphasize the value of integrating multiple sedimentological proxies to identify tropical storm signatures, with clear applications in paleotempestology and coastal management initiatives.