Thermoluminescence dating of calcite – Alpha effectiveness and measurement protocols

Alpha irradiation is less efficient in inducing the thermoluminescence (TL) signal compared to beta and gamma irradiation. Although TL dating has been applied to calcite from various geological contexts, studies of the alpha effectiveness (a-values) of calcite are relatively scarce, and the reported a-values are focused on the 280 °C TL peak of speleothem calcite. In this study, three single-aliquot regenerative-dose (SAR) protocols were applied to measure the a-values of the 280 °C TL peak, the 350 °C TL peak, and the isothermal thermoluminescence at 240 °C (ITL240) of calcite from travertine, limestone and marble samples. The performances of the three SAR protocols were compared and the ITL240 signal was generally equivalent to the 280 °C TL peak TL. The a-values of the 280 °C TL peak of the samples range from 0.19 to 0.24, with a mean value of 0.20 ± 0.01, which are within the range of a-values previously reported for speleothems. The a-values of the ITL240 signal are slightly higher, and the mean value is 0.23 ± 0.01. However, the 350 °C TL peak has a lower mean a-value of 0.15 ± 0.01. The dose response curves for the 280 °C TL peak, 350 °C TL peak and ITL240 signal of the samples have characteristic saturation doses (D0) of 3000–5000 Gy, showing great potential for dating samples millions of years old. •Alpha effectiveness of TL signals from calcite from different rocks are measured.•The mean a-values of the 280 °C TL peak, 350 °C TL peak and isothermal TL at 240 °C are 0.20, 0.15, 0.23, respectively.•TL and ITL signals from calcite have large D0 values ranging from 3000 to 5000 Gy.