A geochemical reconnaissance survey of Sri Lanka using panned mineral  concentrates of stream sediments

R.S. Ramakrishna; R.E. Rajaseelan; J.M.T.B. Karunaratne; M. Balasubramaniam; R.R. Brooks; D.E. Ryan; J. Holzbecher

R.S. Ramakrishna Centre for Analytical Research and Development, Department of Chemistry, University of Colombo, Sri Lanka;
R.E. Rajaseelan Centre for Analytical Research and Development, Department of Chemistry, University of Colombo, Sri Lanka;
J.M.T.B. Karunaratne Centre for Analytical Research and Development, Department of Chemistry, University of Colombo, Sri Lanka;
M. Balasubramaniam Centre for Analytical Research and Development, Department of Chemistry, University of Colombo, Sri Lanka;
R.R. Brooks Department of Chemistry, Biochemistry and Biophysics, Massey University, Palmerston North, New Zealand
D.E. Ryan Trace Analysis Research Centre, Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
J. Holzbecher Trace Analysis Research Centre, Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada

Abstract

Thirteen elements (Au, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sn, Th, U and Zn) were determined in 120 heavy mineral concentrates from Sri Lankan stream sediments of the Highland Group of rocks in central Sri Lanka. The data indicate sporadic occurrences of gold, notably in the north of the region where this metal had not previously been found. The possibility of the existence of a previously unknown area of ultramafic rocks near Balangoda close to the plate boundary with the Vijayan Complex was indicated by high levels of chromium and nickel in the sediments. Background levels of uranium (8 μg/g) were relatively high and three anomalies (>35 μg/g) were detected in stream sediment concentrates. The project has pinpointed several areas where localized intensive exploration for specific minerals should be undertaken. Background levels have also been established for thirteen elements in stream sediment concentrates derived from the Highland Group of rocks.