腾格里沙漠南缘风积物快组分光释光信号选择研究

摘要

Selections of different signal intervals affect the precision of equivalent dose calculation. Six dune samples from Gulang at the southern edge of Tengger Desert were dated using optically stimulated luminescence (OSL) by employing various signal intervals, and a total of 193 aliquots were obtained. Fast-component based equivalent dose (De) analysis was performed by decomposing OSL signals to fast, middle, slow plus background signal. The comparison of SAR De values with fast-component based De values shows that De values of these samples are sensitive to selections of OSL signal intervals, that using the‘early background’ method with channel 1~2(0~0.32 s) as the interval for fast-component signal and channel 3~7(0.32~1.12 s) as the interval for background signal obtains De values that is consistent with fast-component based De values, and that significant differences exist between De values calculated using ‘late background’ method and those calculated using fast-component method, suggesting that ‘late background’ based OSL signal is affected strongly by middle component.%光释光(OSL)信号衰减曲线不同时段信号积分的选择，直接影响到能否有效提取快组分信号，从而影响等效剂量(De)计算的准确性。本文根据腾格里沙漠南缘古浪县附近的两个剖面的6个风成沉积物的共193个单片的单片再生剂量法(SAR)测试结果，将石英OSL衰减曲线分解成快、中、慢与背景信号三个组分。利用分解出的 OSL快组分信号建立再生曲线，求取每个单片对应的 De值，并与4组选择 OSL衰减曲线上不同时段信号积分的SAR法所计算的De值对比。结果表明，腾格里沙漠南缘风成沉积物的De值对信号区间选择方式较为敏感；使用通道1~2(0~0.32 s)作为快组分信号区间，通道3~7(0.32~1.12 s)作为背景信号区间的早期背景信号扣除法获得的 De 值与快组分法计算的 De 值较一致；晚期背景信号扣除法由于受中组分信号的显著影响，计算的De值与真实De值之间存在较大差异。