A detailed post-IR IRSL dating study of the Niuyangzigou loess site in northeastern China

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• 作者：Shuangwen Yi ; Jan-Pieter Buylaert ; Andrew S. Murray ; Huayu Lu ; Christine Thiel and Lin Zeng
• 刊名：Boreas
• 出版年：2016
• 出版时间：October 2016
• 年：2016
• 卷：45
• 期：4
• 页码：644-657
• 全文大小：1844K
• ISSN：1502-3885

文摘

In this study, we report standard quartz SAR OSL and post-IR infrared (IR) stimulated luminescence (post-IR IRSL; pIRIR₂₉₀) measurements made on sand-sized quartz and K-feldspar extracts from the loess-palaeosol sequence at Niuyangzigou in northeastern China. The quartz OSL characteristics are satisfactory. Extensive pIRIR_50,290 dose recovery tests were performed by adding doses on top of the natural dose. We found that dose recovery ratios improve significantly when the test dose ranges between ~15 and ~80% of the total dose, and good dose recovery (within ±5% of unity) can be obtained up to ∼800 Gy. Otherwise, the dose recovery ratio deviates from unity. The D_e values also depend on the test dose size and so we conclude that the effect of test dose size should be routinely considered in pIRIR dating. First IR stimulation plateau pIRIR₂₉₀ results are compared with multiple elevated temperature -pIRIR (MET-pIRIR) data. It appears that the low temperature MET-pIRIR data are strongly affected by poor dose recovery, but this is not the case for the pIRIR₂₉₀ results. Natural signal measurements at the highest (first IR) stimulation temperature on a sample expected to be in field saturation suggest that ~10% signal loss occurs in pIRIR signals. Long-term laboratory bleaching experiments (>80 days) show that a constant (or very difficult to bleach) residual pIRIR₂₉₀ signal is reached after ~300 h, corresponding to a dose of 6.2±0.7 Gy. Quartz OSL and feldspar pIRIR_50,290 ages are in good agreement at least back to c. 70 ka. Beyond this the quartz ages begin to underestimate but the feldspar ages are in agreement with the expected Last Interglacial age palaeosol.