Chemical and strontium isotopic composition of Kaveri, Palar and Ponnaiyar rivers: Significance to weathering of granulites and granitic gneisses of southern Peninsular India

摘要

Strontium (Sr) isotope ratios and major ion abundance were determined on water samples of Kaveri, Palar and Ponnaiyar rivers, collected during the NE monsoon of 2005, when there was unusually heavy rainfall. Sr isotope ratios combined with major ion concentrations were used to determine relative contribution of Sr and major ions by weathering of various rock types exposed in the drainage basin. super(87)Sr/ super(86)Sr ratios were well correlated to Ca/Sr and Mg/Sr ratios in water samples indicating mixing of water with solute load essentially derived by weathering of granitoid gneisses, mafic volcanics and carbonates of the Archean schist belts in the upper reaches with the water draining felsic granulites in the lower reaches.