Constructions of standardised growth curves (SGCs) for IRSL signals from K-feldspar, plagioclase and polymineral fractions

Abstract

Standardised growth curves (SGCs) were established for extracts of potassium feldspar (K-feldspar), plagioclase and polymineral grains from various geological settings (deserts, loess, lake or fluvial deposits) from Northern China. Single-aliquot regenerative-dose (SAR) protocol was used with the measurements of multiple elevated temperature post-IR IRSL (MET-pIRIR) signals from 50 °C to 250 °C with an interval of 50 °C. Regenerative-dose normalisation was applied for the SGC construction. The shapes of the SGCs of K-feldspar vary between IRSL signals measured at different temperatures. For coarse grains (63–180 μm), the SGCs of the K-feldspar, plagioclase and polymineral fractions are close to each other. However, the polymineral fine grains (4–11 μm) have a distinct SGC from the coarse-grain fractions. It may be caused by the difference in alpha irradiation.

Two test doses (145 Gy and 72.5 Gy) were applied to construct the SGCs for K-feldspar. The SGC built with the larger test dose has a larger characteristic saturation dose (D0). Test dose used for equivalent dose (De) measurements need to be the same as the test dose used for SGC construction, otherwise the SGC De may not be estimated accurately. With the same test dose used, the De values estimated from SGCs are identical with the De values generated from individual dose response curves.