A Statistical Appraisal of Geochemical Data o...

A Statistical Appraisal of Geochemical Data of Sediments from Ponnaiyar River, Tamil Nadu, India

Author Name : J. Sankar, C. Sadhu, P. Saravanan

ABSTRACT

The Ponnaiyar river sediments from nine sampling station between Thirukovilur and Cuddalore were subjected to geochemical studies to understand the elemental characteristics and their interrelation and to determine the source of major and trace elements present in the sediments.Chemical analysis was carried out on samples for Si, Al, Fe, Ca, Mg, K, Mn, Ti, P, Li, B, V, Cr, Ni, Zn, Sr, Y, Nb, Mo, Sb, Ba, La, Ce, Pb and Zr. Principal component analysis (PCA) was performed on the chemical analysis dataset of twenty-five elements (major and trace) present in nine bulk sediments.The PCA showed that there are three principal components that govern the migration and dispersion of elements from their source. The granites, granitic-gneiss, charnockites, alkaline syenite-carbonatite, pyroxenites, garnetiferous-sillimanite gneiss, granite-pegmatites, and other granulitic rocks of the Ponnaiyar river basin form the source for all the chemical elements studied.The migration of elements from source to river sediments could have taken place through particulate minerogenic phase as detrital heavy minerals, detrital quartz and feldspars and clay minerals.The average elemental content of the Ponnaiyar sediment exhibits an enhancement of Si, Fe, P, V Cr, Co, Ni, Sr, La, Zr and a strong depletion of Ca, Mg and K relative to the upper continental crust (UCC) values.The study indicates that the felsic and mafic rocks of the drainage basin contribute both major and trace elements to the river sediments.Felsic rocks have played a predominant role in the supply of chemical elements to the river sediments.The higher value of Cr, Ni, Pb, Fe and P might have been derived from anthropogenic input to the river from industrial effluents and chemical contamination from agricultural lands, besides natural geochemical background contribution.

Key Words: Principal Component Analysis, River Sediments, Trace Elements, Provenance