Thermal stability of infrared stimulated luminescence of sedimentary K-feldspar

Abstract

The thermal stability of the infrared stimulated luminescence (IRSL) signal measured at 50 °C as a function of IR stimulation time was investigated using KF grains extracted from sediments from central China. A dependence of thermal stability of IRSL signal on IR stimulation time and stimulation temperature were observed in pulse annealing studies. Relatively lower thermal stability is given by the initial part of the IRSL measured at 50 °C, than the later part of IRSL curve. Based on these observations, the thermal stability of the post-IR IRSL signal stimulated at elevated temperatures (100-200 °C) was also investigated. It was found that at least two groups of traps (shallow and deep) are associated with the IRSL and post-IR IRSL signals. The IRSL signal obtained at 50 °C is mainly from the shallow traps while the post-IR IRSL obtained at elevated temperatures is mainly from the deep traps. The kinetics parameters obtained using pulse annealing test indicate that the shallow IRSL traps are probably associated with the ∼300-350 °C TL peak and the deep traps are probably associated with the ∼400 °C TL peak. The shallow traps (∼350 °C TL peak) are associated with those easy-to-fade traps and the deep traps (∼400 °C TL peak) are associated with hard-to-fade traps.

On the dose dependency of the bleachable and non-bleachable components of IRSL from K-feldspar: Improved procedures for luminescence dating of Quaternary sediments

“…6a that the residual signals measured at higher temperatures are more thermally stable than those measured at lower temperatures: for example, the residual signal stimulated at 100°C starts to decrease from an annealing temperature of 350°C, whereas the 250 and 300°C residual signals are stable up to an annealing temperature of almost 400°C although the residual signal at 300°C appears to decrease at a slightly lower temperature than 200°C signal. A similar trend was observed by Li and Li (2011b) for the total MET-pIRIR signals of a sand dune sample from China, but the pulse annealing curves for the total MET-pIRIR signals from the same set of aliquots of sample LC10-07 exhibit a different pattern. As shown in Fig.…”

Review and assessment of the potential of post-IR IRSL dating methods to circumvent the problem of anomalous fading in feldspar luminescence

“…Based on the reduction of TL from IR bleaching, they suggested that the IRSL traps of their K-feldspar sample mainly originated from deep traps associated with the ~410°C TL peak. In a later study on the effect of IR bleaching on the TL of Kfeldspar from sediments from North China, Li and Li (2011b) found that the IRSL are associated with the 350 and 400°C TL peaks, which led them to suggest that at least two groups of traps (shallow and deep) are associated with the IRSL signals. All these studies suggest that the IRSL signal from K-feldspar is thermally stable over the datable period (e.g., <1 Ma).…”

“…The thermal stability of the pIRIR signal was investigated in several studies (Li and Li, 2011b;Thomsen et al, 2011;Fu et al, 2012b;. Based on a pulse anneal study of the IRSL and pIRIR signals on the K-feldspar grains from several sedimentary samples, Thomsen et al (2011) showed that the pIRIR signal has a greater thermal stability than the 50°C IRSL signal (e.g., heating to ~400°C can erase most of the 50°C IRSL signal, whereas the pIRIR(50,290) signal is still not completely erased by heating to ~550°C).…”

“…Based on a pulse anneal study of the IRSL and pIRIR signals on the K-feldspar grains from several sedimentary samples, Thomsen et al (2011) showed that the pIRIR signal has a greater thermal stability than the 50°C IRSL signal (e.g., heating to ~400°C can erase most of the 50°C IRSL signal, whereas the pIRIR(50,290) signal is still not completely erased by heating to ~550°C). Li and Li (2011b) studied the thermal stability of the IRSL and MET-pIRIR signals from K-feldspar grains. Based on their pulse anneal studies, they suggested that the MET-pIRIR signals at elevated temperatures (>100°C) are more thermally stable than the IRSL signal at 50°C, due to the presence of deeper traps in the MET-pIRIR signals.…”

Determining the cooling age using luminescence-thermochronology

“…Furthermore, the pIRIR and the MET-pIRIR signals from feldspars have been found to be thermally stable up to 400 °C in pulse annealing tests (e.g. Li and Li, 2011b;Thomsen et al, 2011), suggesting that these signals are more thermally stable than the quartz OSL. It is thus expected that the closure temperature of feldspar IRSL is higher than that of quartz OSL.…”