Depth wise analysis of recently excavated Vellar river sediments through FTIR and XRD studies

Abstract

The Fourier transform infrared (FTIR) spectral analysis has been carried out for sediments of Vellar river, Tamilnadu collected at various depths from twenty seven different locations. The minerals such as quartz, feldspar (microcline and orthoclase), kaolinite, palygorskite, calcite, aragonite, montmorillonite, cerussite, hematite, sepiolite, magnesium oxalate and organic carbon are identified. Among these, quartz, feldspar and kaolinite are the major minerals and palygorskite, calcite, aragonite, montmorillonite, cerussite, hematite, sepiolite, magnesium oxalate and organic carbon are minor and traces. The relative distribution of these three major minerals was determined by computing the extinction co-efficient. The crystalline nature of quartz is judged by calculating crystallinity index which shows that the crystalline nature decreases with increase of depth. The observation made through relative distribution, shows that the amount of quartz and feldspar are relatively reduced and that of kaolinite is increased from upper to inner depth. As the depth increases the bands of kaolinite progressively broaden and shift to higher wave number side which suggests that the content of kaolinite increases with disorderedness. From XRD analysis, the minerals such as monazite, zircon and kyanite are additionally identified. The crystalline nature of quartz is also confirmed.