The red, white and blue of quartz luminescence: A comparison of De values derived for sediments from Australia and Indonesia using thermoluminescence and optically stimulated luminescence emissions

Heated quartz, including quartz from volcanic provinces, commonly displays different luminescence characteristics compared with the same mineral in non-volcanic contexts. These differing properties demand thorough investigations into the most suitable dating techniques for samples composed of quartz grains with different origins. In cave settings, independent techniques such as radiocarbon and U-series can prove useful for validating results, but further insights may be gained by comparing the results obtained for quartz using different luminescence emissions. Twenty-two quartz samples have been selected from five areas (Australia, Timor, Flores, Java and Sulawesi) for comparison of the red and blue emissions. The dual-aliquot regenerative-dose protocol was used to estimate the equivalent dose (De) associated with the light-sensitive red thermoluminescence while the single aliquot regenerative-dose protocol was used to measure the De values for single grains and single aliquots, which were optically stimulated by green or blue light, respectively. The results obtained from the red thermoluminescence and optically stimulated luminescence measurements display good agreement with independent dating techniques (within ∼20%). However, the blue emissions exhibit a thermally unstable component, which causes a large underestimation in palaeodoses (on average ∼80%) and an age limit of ∼25 ka, while the red emissions are more thermally stable over geological timescales but produce an overestimation in red TL ages (by ∼13 ka) and low precision (typically ∼24%). These results can be correlated to three different quartz groups, which have been divided according to their luminescence emissions.