Geochemical aspects of serpentinite bodies at Ginigalpelessa off Ambilipitiya, Sri Lanka

Abstract

Ginigalpelessa Serpentine bodies are located along major tectonic boundary between Highland and the Vijayan Complexes - in the South Eastern part of Sri Lanka. Ultramafic rocks and their soils are rich with specific metals such asFe, Mg, Mn, Ni, Co and Cr. Release of certain metallic elements from weathered rock to soil and their in situ concentration have been identified. "MorindaTInctoria" plants which is wide spread in the area is restricted to area underlain by Serpentinite bodies. Ni concentration in the rocks varies between 2250-3340ppm while over 100% - 175% increase in concentration is found in soil. The plant "MorindaTInctoria" shows high concentration of Ni compared to the same plants collected from elsewhere in the country. The restriction of the plant to the particular area and its growth pattern in the area indicate that the plant could be used as an indicator plant for identifying higher concentration of Nisoil . Increased element concentration from the bed rock to soil has been identified for Fe (260%) Mn (270%), Co (280%) and Cr ( over 6700%) Decreased element concentration has been identified for Mg (580%). Very high Cr values found in soils (over 14000ppm of Cr in soils) leads to investigate the effect of Cr for human health in the area.