Attached
The Batticaloa lagoon is the largest lagoon estuarine system in the eastern Sri Lanka, which
margines to the Bay of Bengal. In this study, the sedimentary processes and sediment provenance
of Batticaloa lagoon were assessed by geochemical means. A total of 34 superficial sediment
samples were collected and analyzed for five major oxides, 13 trace elements, total sulfur and
selected halogens. The sediments were strongly enriched for Zr, Mn and Y compared to the PostArchaean Austrarian Shale (PAAS) and Zr, As, V, Mn, Ti, Cr and Y compared to the average Upper
Continental Crust (UCC). This is probably due to the strong weathering under tropical climate and
sorting effect by well circulations of water currents in the lagoon. The low concentrations of total
sulfur and halogens also suggest well water current circulations to deplete marine organic
matters. The cross plots of Zr, Ti and Fe further indicated mineral sorting effect for sediments. The
sediments of Batticaloa lagoon are closer to the sediment recycling and upper crust input, and
away from compositional origin in theTh/Sc-Zr/Sc diagram due to zircon addition. Sediments have
a source composition similar to granite on the mixing curve between granite and ultramafic end
members on the Cr/V-Y/Ni diagram. Therefore, the results suggest a metamorphic granitic origin
for Batticaloa lagoon sediments, and well circulation of water currents in the lagoon, which affect
the well-sorting of sediments.
