早期遗址化石ESR测年等效剂量拟合函数的选择  

The choice of equivalent dose fitting function in ESR dating of old fossil samples

作　　者：谢君绮 韩非 柳华霖 黄曼琛 高峰 XIE Junqi;HAN Fei;LIU Hualin;HUANG Manchen;GAO Feng(Key Laboratory of Earth System Science,Yunnan University,Kunming 650500,China;Yunnan Institute of Cultural Relics and Archaeology,Kunming 650118,China)

机构地区：[1]云南大学地球系统科学重点实验室,昆明650500 [2]云南省文物考古研究所,昆明650118

出　　处：《核技术》2025年第1期122-131,共10页Nuclear Techniques

基　　金：国家自然科学基金(No.42172022);云南省基础研究专项计划面上项目(No.202201AT070211)资助。

摘　　要：在动物牙齿化石样品电子自旋共振测年(Electron Spin Resonance Dating,ESR)中辐照剂量点拟合函数的选择对等效剂量D_(E)的确定至关重要。目前,早期遗址老化石(>1 Ma)的D_(E)拟合常采用双饱和指数(Double Saturation Exponential,DSE)函数,使用该函数时一般需要15个以上剂量点和大于20 kGy的最大辐照剂量(D_(max))才能保证D_(E)值的拟合精度。但在实际应用中存在部分老化石的样品量较少,且缺乏大剂量辐照的准确标定情况,导致无法满足上述DSE函数的适用条件。本研究对涵盖晚中新世至早更新世的化石样品进行了不同拟合函数的对比分析,着重探讨单饱和指数(Single Saturation Exponential,SSE)函数在老化石样品D_(E)拟合中的适用性。研究表明:对11~15个剂量点进行拟合时,对于2000 GyE<4500 Gy和D_(E)>4500 Gy的样品,分别在1.9×D_(E)max<3.5×D_(E)和D_(max)≥6.5×D_(E)条件下采用SSE函数拟合,可以获得与使用DSE函数基本一致的D_(E)结果。[Background]In electron spin resonance dating(ESR)of old fossils,the double saturation exponential(DSE)function is often used for the equivalent dose(D_(E))determination,it generally requires more than 15 dose points and the maximum irradiation dose(D_(max))greater than 20 kGy to ensure the fitting accuracy,which limit the practical application of dating old fossils by ESR method with insufficient sample size.[Purpose]This study aims to explore the feasibility and reliability of using the single saturation exponential(SSE)fitting function to fit fewer dose points with lower D_(max)to obtain the D_(E)values of the fossil teeth from the late Miocene to the early Pleistocene,and compared with the ones determined by DSE function.[Methods]Firstly,17 fossil samples were taken from seven fossil sites in different regions of China and Myanmar,and their ages covered the late Miocene to early Pleistocene.Then,three fitting functions,i.e.,DSE,SSE and EPL-exponential plus linear,were employed to obtain the D_(E)values of ESR using the additional dose method.Finally,the influence of different D_(max)on the D_(E)results of three fitting functions was investigated by comparative analysis.[Results]Comparison results show that:(1)The SSE and DSE function are used to fit the 15 dose points with D_(max)=50 kGy,and the D_(E)-SSE results of 11 samples are basically consistent with the D_(E)-DSE results,meanwhile the precision of the fitting results of SSE function is generally higher than DSE cases.(2)For samples with D_(E)>4500 Gy and 2000 Gy<D_(E)<4500 Gy,the results of SSE and DSE are basically consistent within the error range under the conditions of D_(max)≥6.5×D_(E)and 1.9×D_(E)<D_(max)<3.5×D_(E),respectively,which can provide the recommended dose value of D_(max)for samples with D_(E)>2000 Gy when using SSE function.(3)For fossil samples with 2000 Gy<D_(E)<4500 Gy,the SSE function can be used to fit the 11 dose points with D_(max)≤10 kGy,and the D_(E)results are generally consistent with the DSE function within the erro

关 键 词：牙化石 ESR测年 等效剂量 拟合函数 

分 类 号：P534.6[天文地球—古生物学与地层学] P597.3[天文地球—地质学]