Elemental and mineralogical analysis of beachrocks in Southern coastal region Sri Lanka

Abstract

Beachrock is coastal sediment that has been cemented primarily by calcium carbonate within the intertidal zone in tropical and subtropical regions. Considering that beachrock has the potential to inhibit coastal erosion, we performed laboratory tests to understand the formation mechanism of beachrocks in southern coastal regions of Sri Lanka. The mineralogical composition of beachrock samples were identified by FT-IR spectroscopic technique. The constituents of minerals present in the beachrocks were further confirmed by XRD analysis. Elemental concentrations of beachrock samples have been examined using WD-XRF spectrometry. The formative environment (sea water) was analyzed using EDTA titration, AAS, UV/Vis spectroscopy and Iron Chromatography. The results reveal the presence of minerals aragonite, calcite, orthoclase, quartz, albite, kaolinite and lime in the beachrocks. According to the results, there is a high probability to precipitate CaCO3 from the sea water in southern coastal regions indicating a positive formative environment for beachrocks. Hence, by appropriate regulation of the conditions could foster the development of manmade beachrocks to control the coastal erosion.