Electron spin resonance dating of shells from the sambaqui (shell mound) Capelinha, São Paulo, Brazil

Abstract

Capelinha is a fluvial sambaqui (Brazilian Shell Mound) located in the Ribeira Valey in the State of São Paulo that is being studied. It is one of the oldest sambaquis located along a river dated so far in this region. The use of ESR to date other shells stimulated our group to apply this method to the Capelinha site. Shells from land snails (Megalobulimus sp.) obtained in two levels of excavations were analyzed; one of them was in contact with a skeleton that was dated by C-14. The archeological doses obtained were (8.05±0.07) Gy and (9.50±0.03) Gy. Since the last site was previously dated by C-14 (Beta -Analytics, Beta 153988) giving: 8860 +/-60 years BP (conventional age) and 10180 to 9710 years BP (calibrated age), the archeological dose found for this shell was used to determine the local rate of (0.93 to 0.98) mGy/year, that aggress with other surveys done in the region. Using this dose rate the age of the second shell was found to be 8.14 to 8.73 ky BP that agrees with the stratigraphy of the site.

EPR study of gamma induced radicals in amino and iminodiacetic acid derivatives

“…Moreover, the hyperfine structure of the EPR spectrum (when it is well resolved) provides more important information about the radical than the g-value, because most radicals detected are carbon or nitrogen centered radicals and the spectra positions are almost in the same magnetic field range [1]. The EPR technique has been widely used for long time in the identification of irradiation damage centers in many substances including drugs, amino acid and iminodiacetic acid derivatives [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. L-glutamine and iminodiacetic acid powders were gamma-irradiated and studied by EPR at room temperature [19,20].…”

Dose estimation, kinetics and dating of fossil marine mollusc shells from northwestern part of Turkey

“…In recent years, Electron Spin Resonance (ESR) technique has also been used for dating Quaternary fossils of mammals, human remains and shells of both marine and terrestrial molluscs (Molodkov, 1988; Barabas et al, 1992aBarabas et al, , 1992bMolodkov, 1993;Radtke, 1997, 1999;Engin et al, 2006;Kinoshita et al, 2006, Kerber et al, 2011. This technique is useful for Quaternary fossils because it can determine ages older than the maximum limit of 14 C (about 50,000 years) its upper limit is dependent on the saturation of defects and signal stability in older samples and on the thermal stability of the defects (Ikeya and Ohmura, 1981;Radtke et al, 1985;Shimokawa et al, 1992; Ikeya, 1993; Schellmann and Radtke , 1997;Lopes et al, 2013).…”

Identification of free radicals induced by gamma irradiation in amino acid derivatives

“…The electron paramagnetic resonance (EPR) has been widely used for the identification of irradiation damage centers in many substances including amino acid and their derivatives [5][6][7][8][9][10][11][12][13][14][15]. In previous study, Almanov et.al.…”