SAR–RTL dating of single grains of volcanic quartz from the late Pleistocene Toya Caldera

We performed the single aliquot regeneration–red thermal luminescence (SAR–RTL) dating on single quartz grains from Toya Caldera, northern Japan, which erupted during the late Pleistocene. The use of an H7421-40 photomultiplier tube and a combination of R60 and IRC65L filters, which were developed for isothermal red thermoluminescence (IRTL), resulted in improved RTL signal detection, enabling weak RTL signals to be detected from a single quartz grain. In addition, the use of a silver holder with a biotite shield helped to reduce the black body emissions from the heating device. Analysis of RTL glow curves obtained for individual grains suggests that quartz grains that yield a sharp peak (sharp type) are essential grains derived from a magmatic source, showing similar erupted ages, whereas quartz grains with broad peaks (broad type) are detritus in origin and show a range of ages. The average ages of the four tested samples, which range from 104 ± 15 to 118 ± 15 ka, are concordant with the age of eruption (112–115 ka) estimated based on geological evidence. In conclusion, SAR–RTL dating of single quartz grains is reliable for dating the early stage of late Pleistocene volcanic events.