LUMINESCENCE DATING USING FELDSPARS - A TEST-CASE FROM SOUTHERN NORTH-ISLAND, NEW-ZEALAND

Luminescence dating using coarse-grain potassium-rich feldspars is applied to a suite of 12 dune sands collected from southern North Island, New Zealand. The expected ages of the samples range from modern to 350 ka. Luminescence ages were calculated using thermoluminescence and infra-red stimulated luminescence measurements to determine total bleach and regeneration equivalent doses for each sample. No systematic difference was observed between any of these different methods. Withstanding the uncertainties in the independent ages of some samples, comparison of the luminescence ages with those suggested by the independent age control suggests that reliable luminescence ages can be obtained for samples younger than 130 ka. Luminescence ages for older samples appear to underestimate the true age and it is suggested that this may be due to long-term fading of the luminescence signal as suggested by Mejdahl (1989).