Nature and timing of long-term landscape evolution by optical dating of single grains of sand

点击翻译按钮获取中文摘要

We are requesting funding for the purchase of a Risø dual-laser single-grain optically-stimulated luminescence (OSL) unit, and supporting hardware and software, that is designed to fit directly onto my (Lian’s) existing Risø model TL/OSL-DA-20 dating system. The upgrade will modernize the existing system, significantly increase its usefulness, and extend its life for another decade; it will also allow for the seamless addition of other components available from the manufacturer. The dual-laser single-grain OSL attachment will allow us to scrutinize the luminescence signals from quartz and K-feldspar sediment samples at the single grain level (the smallest fundamental unit of analysis in optical dating) which will, in turn, allow us to significantly increase the precision and accuracy of optical ages determined from them. This is accomplished by identifying and separating grains (quartz and K-feldspar) in a sample with different age populations, and by detecting and avoiding grains (quartz) with malign luminescence properties that can negatively effect calculated ages, or by identifying and including only those grains with luminescence properties that allow for much older ages to be calculated (so-called ‘super grains’). Single grain analysis will allow us to better understand, and perhaps more effectively circumvent, the malign effect of anomalous fading in K-feldspar and other feldspar minerals.