Start Thermoluminescence tl dating

Thermoluminescence tl dating

The natural radiogenic dose rates for the alkalic basalts calculated on the basis of assumed secular equilibrium range from 0.228 to 0.462 rad per year and average 0.335 rad per year exclusive of the cosmic-ray energy dose and with the alpha-particle component equal to one-tenth of the total alpha decay energy. The high-temperature artificial TL peak occurs at a lower temperature than the corresponding natural TL peak owing to the presence of a large number of electrons retained in traps near the lower end of the trap-depth energy range in samples whose TL is measured a short time after intense artificial irradiation.

Ratios of natural to artificial TL intensity, when normalized for natural radiation dose rates, were used to quantify the thermoluminescence response of individual samples for age-determination purposes.

The TL ratios for the alkalic basalt plagioclase were found to increase with age at a predictable exponential rate that permits the use of the equation for the best-fit line through a plot of the TL ratios relative to known age as a TL age equation.

The basic TL properties of the plagioclase from the two rock types are similar, however, and TL dating of tholeiitic basalts should eventually be feasible over the age range 10,000 to at least 200,000 years B. The average composition of the plagioclase separates from the alkalic basalts ranges from oligoclase to andesine; compositional variations within this range have no apparent effect on the TL ratios.