Single-grain luminescence dating of K-feldspar based on the pre-dose MET-pIRIR protocol

Abstract

Potassium-rich feldspar (K-feldspar) is widely used in luminescence dating due to its high saturation dose, allowing the determination of ages for older sediments. Previous studies have shown that the ‘sensitivity’ of the post-infrared infrared stimulated luminescence (pIRIR) signal can retain a ‘memory’ of the pre-dose received but can be reset by sunlight bleaching. Building on the development of multi-aliquot and single-aliquot pre-dose multi-elevated-temperature post-IR IRSL (pMET-pIRIR) procedures, we investigate the performance of the single-aliquot regenerative-dose (SAR) pMET-pIRIR procedure for K-feldspar at the single-grain level. Solar bleaching experiments demonstrate that the sensitivity of the IRSL and MET-pIRIR signals can be effectively reset by a 3 h solar simulator bleaching step applied after each regenerative cycle. Integrating the SAR pMET-pIRIR procedure with the standardised growth curve (SGC)-based L_nT_n method successfully overcomes sensitivity carry-over, mitigates anomalous fading, extends the dating range and improves measurement efficiency for K-feldspar luminescence dating. Equivalent doses (D_e) can be determined using the sensitivity-corrected signal (L_x/T_x), regenerative signal (L_x) and test dose signal (T_x), providing flexibility across different dose ranges and improving dating reliability through cross-validation. Application to three sediment samples from China, including samples with independent known ages, confirms the method's ability to obtain accurate D_e values up to ∼1600 Gy (∼440 ka), with the potential to date samples approaching ∼1 Ma using the L_x and T_x signals. The single-grain SAR pMET-pIRIR method offers a promising approach for dating older sediments and investigating heterogeneous luminescence behaviours among grains or post-depositionally disturbed deposits.