Attached
Coral reefs are related to contemporary processes and sea-level changes over the
geological time. Although corals can be dated from late Cambrian to Present, most
modern reefs date approximately 5000-7000 years BP. Several Holocene inland coral
reefs are preserved in the southern coastal belt of Sri Lanka as pocket deposits. These
deposits can be used effectively as proxies to determine the paleo-sea level and
environmental changes in Sri Lanka. Well preserved coral samples collected from the
southern coastal area were investigated by X-Ray Imaging to identify the skeleton
structure. Scanning electron microscope (SEM) combined with EDX and X-ray
diffractometer (XRD) were used to identify the external morphology and elemental
composition. Chemical composition of samples was analyzed using an inductively
coupled mass spectrometer (ICP-MS). Samples were selected based on annual growth
bands recognized by X-Ray imaging. SEM and XRD and analyses indicated the
presence of aragonite crystal structure suggesting the growth of the skeleton at a deep
ocean environment. Ratios of Mn/Ca, Fe/Ca and Pb/Ca indicated the sedimentation of
the coral surface occurred after being exposed or at the termination of the coral colony.
Mg/Ca (1.45 x 10-3
-1.58 x 10-3
), Sr/Ca (21.31-21.79) and Ba/Ca (10.93 x 10-3
-47.25 x 10-
3
) ratios indicate 6 different ocean temperature variations. Therefore, inland corals of Sri
Lanka can be used to identify sea level changes and detailed mapping combined with
chemical compositional variation can be used to predict paleo-sea level changes.
