Affiliation: | aFaculty of Science, Osaka City University, Sugimoto, Sumiyoshi-Ku, Osaka 558-8585, Japan;bCentre for Earth Science Studies, 7250 Akkulam, Thuruvikkal P.O., Trivandrum 695 031, India;cDepartment of Geology, Peradeniya University, Kandy, SriLanka |