I-P2O5 diagrams as an indicator of depositional environment in marine sediments: preliminary findings (Sri Lanka)

Abstract

The concentrations of Br and I in marine sediments have been used to categorize the sedimentary environments of diferent coastal regions of the world with respect to organic matter contents. The present study uses the concentrations of Br, I and P 2O5 of diferent marine settings as a new proxy to interpret the depositional environments. A total of 150 coastal lagoon sediment samples (suspended sediments, surface sediments and sediment cores) were analyzed for Br, I and P2O5 concentrations by X-ray fuorescence spectrometry. They were compared with the Br, I and P2O5 concentrations of the 2004 Indian Ocean tsunami sediments. Sediments from various sources are separately clustered in I–Br plot and a trivial negative correlation is found for the whole plot. A similar correlation pattern exists in the I–P2O5 diagram. This correlation is explained by the distribution of marine plants (higher and lower) in diferent sedimentary environments of the coastal profle. Therefore, the concentration of I and its relation to P 2O5 can be used as a tool to identify sediment depositional environments in marine settings.