Particle Size Characterization and Late Holocene Depositional Processes in Vembanad Lagoon, Kerala: Inferences from Suite Statistics

In this paper, we present the textural characteristics, and Tanner's bivariate plots of grain size parameters to understand the depositional processes in a lagoonal system during the Late Holocene. For this purpose, 16 core samples recovered from the Vembanad lagoon, the largest backwater system on the west coast of India, were investigated. In northern and southern sectors of the lagoon, sand is the dominant textural facies, while in the central sector mixed textural facies - muddy sand and sandy mud - are prevalent. Suite statistics suggest that open- and closed-basin conditions prevailed, which punctuated the high and low energy conditions. High-energy conditions prevailed in northern and southern parts of the lagoon, particularly in areas close to the river mouths. Other parts of the lagoon exhibit low to moderate energy regime and open-to-restricted estuarine conditions. The study emphasizes that the bivariate plot is an extremely useful tool in distinguishing between open- and closed basin conditions in coastal environments.