Facies architecture and textural attributes of the Late Quaternary cliff embankment sections of the Sai River, Central Ganga Plain, India

The cliff embankments are covered as sediments from the floodplain run on both sides of the river. Various sediments transportation and depositional mechanism are contained in these floodplain deposits. For better understanding of depositional history of the floodplain sediments cliff embankments along the Sai River at the villages of Chaukhada and Khatihara in the districts of Pratapgarh and Jaunpur, respectively, were analysed using a laser particle size analyser. The common facies observed in the studied sections are very silty sandy mud, very silty sand, slightly silty sand and very silty slightly sandy mud accordingly. Indurated calcretes are also observed in the very silty sandy mud layer in the Chaukhada section. The Chaukhada section has mean size value ranging from 2.80 phi to 4.98 phi while Khatihara section has these values ranging from 3.80 phi to 4.27 phi, implying coarse silt to very fine sand size range for both the cliff section. The sediments in both of the investigated cliff sections are poorly to very badly sorted, as seen by the sorting (standard deviation) values for the Chaukhada section, which are ranging from 1.12 phi to 2.22 phi, and the Khatihara section, ranging from 1.30 phi to 1.84 phi. The sediment samples displayed the skewness values ranging from 0.23 to 0.34 for the Chaukhada section and 0.09 to 0.32 for the Khatihara section, indicating that the sediments are very finely skewed. The kurtosis value ranging between 1.24 to 1.73 for the Chaukhada section and 1.22 to 1.72 for the Khatihara sections shows that the sediments are leptokurtic to very leptokurtic in nature. Bivariate plots of textural parameters have been also utilized to figure out the depositional environment. The C–M plot indicates that the graded to uniform suspension was the primary mechanism of transportation for all the sediments.