Abstract:
Beachrocks are sedimentary structures commonly observed where there is warm sea
water in tropical and subtropical regions as a result of cementation by CaCCb of
coastal sediments in the tidal zone. Comprehensive studies have been carried out to
determine the formation mechanisms of beachrocks specially Japan to improve an
alternative countermeasure against erosion by man-made rocks. When focusing on
formation mechanism of beachrocks elemental and mineralogical composition is
vital. Considering this important application, we used spectroscopic techniques to
understand composition of beachrocks in southern coastal region between
Ahangama to Kaikawala and Uswetakeiyawa in the western coastal region of Sri
Lanka. The presence of minerals in beach rock samples in southern coast were
identified by FT-IR spectroscopic technique. The constituents of minerals present in
the beach rocks are further confirmed by XRD technique. Elemental concentrations
of beach rock samples have been analyzed using technique of WDXRF spectrometry.
Uswetakeiyawa beachrock was mainly analyzed by using EDX in SEM. Beachrocks
in southern coasts is comprise higher percentage of Aragonite which is the
polymorph of CaCCb, frequently founded in most of the sites in the world. Further
the composition shown similarities with Indian (Tiruchendru) and Japan (Okinawa)
beachrock occurrences. Comparative to the composition of southern coast
beachrock, XRD analysis did not indicate any CaC03 polymorphs Uswetakeyyawa,
beachrocks. Instead it indicated the presence of Kutnohorite (Ca(Mn,Mg,Fe)(C03)2).
Citation:
Edirisooriya, K.V.U.I., Thilakarathna, M.A.D.P., Vijitha, T., Dassanayake, A.B.N., & Jayawardena, C.L. (2019). Analysis of beachrock samples along Southern and Western coasts of Sri Lanka by spectroscopic methods. In D.M.D.O.K. Dissanayake & G.V.I. Samaradivakara (Eds.), Proceedings of International Symposium on Earth Resources Management & Environment 2019 (pp. 41-49). Department of Earth Resources Engineering, University of Moratuwa.
