Optical dating sediments

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The method involves measurement of the luminescence emitted when the quartz is optically stimulated, and yields the time which has elapsed since the sediments were last deposited.The luminescence originates from charge in traps associated with the 325 C TL peak, and the kinetics of charge movement have been carefully considered in the formulation of the dating procedure.The OSL dosimeter provides a new degree of sensitivity by giving an accurate reading as low as 1 mrem for x-ray and gamma ray photons with energies ranging from 5 ke V to greater than 40 Me V.The OSL dosimeter's maximum equivalent dose measurement for x-ray and gamma ray photons is 1000 rem.

The signal from the tube is then used to calculate the dose that the material had absorbed.The OSL ages have large standard errors mainly due to small sample sizes, relatively poor luminescence characteristics and uncertainties in dose-rate determinations.The technique of optical dating has been applied to quartz extracts from geological and archaeological sediments.Feldspar IRSL dates generally overestimate the age, probably due to incomplete bleaching.The data show that during the last glacial cycle north-eastern Finland was not glaciated until MIS 5b, around 90 ka.

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