Some sedimentological aspects of Vembanad Lake, Kerala, West Coast of India

Abstract

Average depth in the Vembanad Lake south of Tannirmukkom bund (lat. 9ᵒ30' to 9ᵒ40'N and long 76ᵒ21' to 76ᵒ26'E) is 3 m while the maximum depth being 8.5 m. Quartz is the main constituent of the sediment which is an admixture of clay, silt and sand. Lesser amounts of muscovite, feldspar, chlorite, heavies, clay minerals and shell fragments are also present. Heavy mineral assemblage indicates that the sediments are derived from the charnockites, granite gneisses, khondalites and pegmatites. Landsat imagery of this area is characterised by number of beach ridges oriented in direction varying from 10ᵒ-190ᵒ to 155ᵒ-335ᵒ. Two main processes are responsible for the formation of Vembanad Lake - an initial tectonic phase followed by natural sedimentation processes affected by waves, currents and tides.