萨拉乌苏河流域现代沙丘沙钾长石单颗粒释光测年  

K-feldspar single-grain post-IR IRSL dating of modern dune sand in the Salawusu River Valley

作　　者：谢佳容 温小浩[1] 欧先交[2] 牛东风 王双双 邱明昆 Jiarong Xie;Xiaohao Wen;Xianjiao Ou;Dongfeng Niu;Shuangshuang Wang;Mingkun Qiu(School of Geography,South China Normal University,Guangzhou 510631,China;School of Geography and Tourism,Jiaying University,Meizhou 514015,Guangdong,China;School of Geography,Lingnan Normal University,Zhanjiang 524048,Guangdong,China)

机构地区：[1]华南师范大学地理科学学院,广东广州510631 [2]嘉应学院地理科学与旅游学院,广东梅州514015 [3]岭南师范学院地理科学学院,广东湛江524048

出　　处：《中国沙漠》2024年第6期135-145,共11页Journal of Desert Research

基　　金：国家自然科学基金项目(41771003,42171005,41301004);中国国家留学基金项目(202008440603);校地合作项目(slws20230508)。

摘　　要：沙漠沉积序列是重建过去气候环境变化的重要材料。本研究利用释光单颗粒测年技术对毛乌素沙地萨拉乌苏河流域的现代沙丘沙进行了石英和钾长石的年代测试。对采集的3个样品分别提取石英和钾长石矿物组分,应用单颗粒测片SAR测试流程测试了样品中石英的等效剂量,应用两步红外激发的单片再生剂量流程(post-infrared infrared-stimulated luminescence,pIRIR流程)测试样品中钾长石的等效剂量,剂量恢复试验和释光特性等各项检验均符合要求。结果表明:(1)样品中石英信号很弱,不适用于该区域的年轻样品的释光测年。(2)采用pIRIR170测试程序对3个现代样品LJB-MD-01、SCHGCMD-01和M01中的钾长石进行等效剂量测试,循环比大部分为0.9~1.1,热转移大多小于10%,结果可靠。(3)IRSL50信号的异常衰退系数(单位为%/10a)为1.99±0.20~2.72±0.73;pIRIR170异常衰退系数为0.02±0.03~0.69±0.31,指示钾长石pIRIR170信号的异常衰减可以忽略。(4)3个地表沙丘沙的钾长石pIRIR170最小年龄模型年代结果分别为115±15、150±20、25±5 a,与理论年龄基本吻合;中值年龄模型年代结果分别为455±65、420±55、30±25 a,比理论年龄稍老。这说明单颗粒钾长石pIRIR170技术适用于该地区的沉积物测年,为包括毛乌素沙地在内的一些沉积物因石英信号弱而无法进行释光测年提供新的思路。Sedimentary records in the deserts are important archives for reconstructing the paleoclimate and paleoenvironmental change.In this study,three samples(LJB-MD-01,SCHGCMD-01,and M01)were collected from modern dunes in the Salawusu River Valley in the Mu Us Desert.Quartz single-grain optically stimulated luminescence(OSL)dating and K-feldspar single-grain post-infrared infrared stimulated luminescence dating(pIRIR)was used to determine the chronology of the sand dunes.The OSL and IRSL characteristics of the samples and the dose recovery test validate the dating protocols.The results suggest that:(1)the quartz OSL signal is very weak and is not suitable for OSL dating of young samples in the study area.(2)equivalent dose(De)determination of K-feldspar using pIRIR170 protocol is reliable,with recycling ratio mostly ranging from 0.9-1.1,and recuperation less than 10%.(3)the anomalous fading rate(g-value)of IRSL50 signals are 1.99±0.20 to 2.72±0.73%per decade and the g-value of pIRIR170 are 0.02±0.03 to 0.69±0.31%per decade,suggesting that the low anomalous fading of pIRIR170 can be neglected.(4)The K-feldspar pIRIR170 ages for the three surface sand dunes,determined using the minimum age model,are 115±15 years,150±20 years,and 25±5 years,respectively.These values align closely with the theoretical ages.The central age model estimates for the same dunes are 455±65 years,420±55 years,and 30±25 years,respectively.These estimates are older than the theoretical ages.Thus,the current work suggests that K-feldspar single-grain pIRIR dating is applicable in the study area and provides a new approach for dating sediments,including the Mu Us Desert sediments,where OSL dating technology is not feasible due to the weak quartz signal.

关 键 词：毛乌素沙地 现代沙丘沙 释光测年 单颗粒 钾长石 

分 类 号：P597.3[天文地球—地球化学]