钾长石矿物在全新世样品光释光测年中的应用与校正问题

使用钾长石进行释光测年时，由于长石的释光信号存在异常衰减，会导致沉积事件年龄的低估。对中国北方4个全新世样品分别使用石英和钾长石矿物组分释光测年，通过测量钾长石的衰退系数(g值)对钾长石使用再生剂量法获得的表征年龄进行了校正。发现对于本文所研究的年轻样品钾长石表征年龄与石英年龄相比系统偏小约2％～9％，钾长石校正年龄与石英年龄相比则严重偏大约16％～40％，表明使用g值无法校正年轻样品的钾长石年龄。对于年轻样品，钾长石IRSL信号异常衰减现象对测年结果的影响是可以忽略的。

IRSL DATING AND CORRECTION FOR HOLOCENE SAMPLES WITH K-FELDSPAR

The K-feldspar bearing samples studied in this paper was collected from Section QJD-1（39°54′23.9″N，105°54′9.4″E；    elevation 1022.9m）which is located in the Northern Ulan  Buh Desert，Inner Mongolia，China. Because the anomalous fading of inferred stimulated luminescence(IRSL)signal leads to underestimation of the burial age by using K feldspar，so in this study，optical stimulated luminescence（OSL）by quartz and K feldspar respectively dated four Holocene samples from section QJD-1.Samples QJD-1-6，QJD-1-26，and QJD-1-50 are aeolian fine sand；sample QJD-1-32 is lacustrine silty clay；    and all of these samples suffered complete bleaching before deposit. Quartz ages and K feldspar demonstrated ages were obtained using double single aliquot regenerative dose protocol(Double SAR). The luminescence measurements were completed on a RisoDA-15-OSL/TL reader and the measurements of radioactive elements were completed by means of neutron active analysis(NAA). The quartz ages of samples QJD-1-26，QJD-1-32 and QJD-1-50 are 7.06±0.37ka，7.81±0.61ka and 8.09±0.44ka，respectively and K feldspar demonstrated ages of them are 6.52±0.57ka； 7.64±0.57ka and 7.62±0.64ka，respectively. It was found that for these samples，their K feldspar demonstrated ages are about 2％～9％ lower than their quartz ages. But the ages obtained by correcting the K fledspar demonstrated ages by the  g value，which is measured in laboratory，are about 16％～40％higher than the quartz ages. Why？ The main reason might be that thermal transfer to exist and the signal delay with time too small at laboratory time scale. It is indicated that the g correction dating by K feldspar is not accurate for Holocene samples，but the impact of anomalous fading on IRSL dating by K-feldspar could be ignorable for Holocene samples. Therefore，the routine IRSL dating by K-feldspar can be used to establish an age framework if there is not available OSL ages from quartz.