Electron spin resonance dating and xrd analysis of ancient marine shell recently excavated in tamilnadu, india

Electron spin resonance (ESR) dating of ancient marine shell has been made using the paramagnetic defects produced by natural radiation. The total dose of natural radiation of the materials termed as archaeological dose estimated from ESR signals of defects in marine shell recently excavated from the archaeological site Alagankulam, Tamilnadu state, India. The sample was divided into nine sets which were given an artificial dose (AD) by using γ irradiation of 50Gy, 100Gy, 200Gy, 400Gy, 600Gy, 800Gy, 1600Gy, 2400Gy and 3200Gy respectively. From the observed ESR spectra with g factor 2.0036, 2.0007 and 1.9973 have been used to estimate the age by assuming the external dose rate to be 1.12 ± 0.08 mGy/a. The calculated age of the sample is 232 ± 74 ka, which correspond to the middle stage of the Pleistocene epoch. The ESR studies on marine shells have potential in evaluating the relative importance of sea level changes paleoclimate and events shaping coastal zones. The X-ray diffraction (XRD) reveals the preservation condition of the shell sample and evidences the diagenesis in the shell over the burial period.