Infrared stimulated luminescence (IRSL) dating of late-Holocene aeolian sands in the Mojave Desert, California, USA

Abstract

A new method of dating potassium feldspar grains from aeolian sands is demonstrated. A luminescence signal is measured whilst the grains are stimulated in the near infrared at 880 nm. A surface sand sample gave an age of 40 ± 15 years, showing that this method is able to provide ages for very young samples. Since the measurement of an infrared stimulated luminescence (IRSL) signal can take place with a short infrared exposure, the IRSL signal of the grains is not depleted; thus growth curves can be obtained for 5 mg sample aliquots. This procedure was exploited in this paper.Dates were obtained for 10 samples from the Kelso dune field as a demonstration of the applicability of the method in a desert environment where there is no material suitable for radiocarbon dating. Although the number of dates are limited, sand from an area at the eastern end of the dune field with crescentic dunes showing a different wind direction from that of today had an age of 4115 ± 335 years, similar to the 3960 ± 385 years for another sand unit nearby. At the western end of the dune field differently oriented crescentic dunes gave ages of 1540 ± 135 and 1470 ± 145 years, indicating a different phase of aeolian activity. Reworking in the late Holocene is proposed for areas with dates ranging from 845 to 105 years.