Textural characteristics of surficial sediments along the Noakhali coast, Bangladesh: An implication for mineral placer deposits exploration

This study aimed to explore mineral placer deposits analyzing textural characteristics; mean size (Mz), standard deviation (sigma i), skewness (Ski), kurtosis (K-G), and the depositional environments of surficial sediments deposited in the Noakhali coast along the Meghna River estuary. A total of nine sediment samples were collected, and the textural parameters were analyzed by a laser particle size analyzer (Microtrac S3500). The mean size of the sediment samples ranged from 3.063 Phi to 5.11 Phi, where the seven samples exhibited sandy-silt texture and only two samples silty-sand texture. However, all the samples presented unimodal grain size distribution. A minimal amount of clay (0.12-1.4%) had been found in three samples collected from Urir Char Island. Higher values of standard deviation (4.15 F to 5.76 F) indicated extremely poorly sorted sediments. Skewness value varied from 0.107 to 0.510 expressed fine to very fine skewness, and kurtosis value from 0.1033 to 1.525 exhibited a mesokurtic to very leptokurtic nature of the sediments. These textural characteristics indicated a low to moderate energy deposition of finer (mostly silt), unidirectional, and riverine sediments. Linear discriminant analysis (LDA) results revealed the littoral, shallow marine, and fluvial deposition of the sediments. CM pattern showed the deposition of sediments by graded suspension without rolling and uniform suspension. Both of these processes indicated low to moderate energy deposition of sediments. As the majority of samples were silt dominated, there are very low prospects of finding valuable heavy minerals except two locations (SP-04, 06) where sand is dominated, and minerals placers could be found there. Low to moderate depositional environments also indicated fewer prospects of finding mineral placer deposits in the studied area. (c) 2022 Elsevier B.V. All rights reserved.