Textural characteristics of the surface sediments of a Tropical mangrove ecosystem Gulf of Kachchh, Gujarat, India

Mangroves in gulf of Kachchh, Gujarat, India has been studied for grain size spectrum and textural parameters namely phi mean, standard deviation, skewness and kurtosis. Grain size spectrum shows a marked variation in the upstream riverine input stretch. Variation of energy conditions is controlled by the fluvial profile in the channel. Textural pattern shows complicated profile as a result of the fluctuation in the physico-chemical conditions due to fluvial-marine interaction. Abundance of very fine sand to fine sand shows the prevalence of comparatively low energy condition in the mangrove creek zones. Linear Discriminate Function Analysis (LDF) of the samples indicates shallow marine environment origin for all samples collected from this mangrove ecosystem. Riverine sediments show a wide range of textural facies including muddy sand. It has also been observed that a progressive enrichment of silty-sand in the downstream region. CM diagram (C= one percentile in microns, M=Median in microns) of Gulf of Kachchh sediments suggests that deposition takes place by (1) rolling (2) rolling and suspension and (3) graded suspension. Rolling and suspension population is dominant in the river/creeks deposits, which is also supported by uniform grain size distribution of sediment load augmented by turbidity current.