【作者】 尹金辉；

【导师】 卢演俦；

【作者基本信息】 中国地震局地质研究所 ， 构造地质学， 2006， 博士

【摘要】 提高样品测定年龄的精度和可靠性一直是同位素年代学研究的重要课题。目前已有20余种方法被应用和有可能用来测定第四纪地层及地质灾害事件的年龄或年代,但14C测年法是测定晚第四纪特别是全新世地质灾害事件年代的优先使用方法,其理论严格完整,技术成熟,而且适用于14C法测年的样品品种多并容易找到。然而土质样品高精度14C年龄测定和可靠的全新世地层年代学是全新世地质灾害研究中一个非常突出且亟待解决的问题,一直困扰着地质灾害事件的深入研究的挑战性问题。如准确地建立古气候、古环境变化的时间过程,对于预测未来环境变化有着重要意义,特别是以十年、百年乃至千年尺度的气候变化和快速气候突变事件对气候和环境变化的预测以及社会可持续发展尤为重要。因此,本论文将试图开展古土壤不同组分的14C测年对比研究,提高这类样品的14C年龄的可靠性;另一方面把时序已知系列样品的高精度14C测年技术应用在地质灾害事件研究中,期望获得高精度14C日历年龄,减小地质灾害事件年代的不确定性。本论文在这两个重要方面进行了一系列相关的研究工作,获得的主要成果和认识如下。一、Quantulua–1220低本底液闪仪的性能测定本文是依托所在工作单位中国地震局地质研究所14C实验室拥有的Quantulua-1220低本底高灵敏度液闪仪测年手段,开展地质事件年代学研究工作。为检验实验室测年流程的可靠性,使用中国糖碳、合成本底、已知年龄样品来评估实验室的本底、样品淬灭、液闪仪探测效率及仪器的长期稳定性等重要性能指标是否满足14C测年要求,保证测试的14C数据可靠,经过上述的比对测试结果表明:(1)在一般工作环境下,液闪仪的本底低于0.5cpm,最大可测年14C年龄估计值为48 Ka BP;(2)根据系列糖碳测量出的计数率和猝灭参数SQP(E),并采用测量相对效率变化方法建立液闪仪的猝灭校正曲线方程为C=0.002630040912*X+10.99101753,然后对本实验室引进液闪仪测量的261个14C样品的猝灭参数统计后,认为液闪仪由于猝灭因素引起的年龄偏差不超过80年;(3)已知年龄树轮样品的14C年龄比对结果表明,建立的14C测年工作方法和流程合理可靠。二、古土壤不同组分14C测年古土壤样品在陆相沉积物中出露比较普遍,经常被用来确定全新世地质事件14C测年的主要材料,以便建立起古地震和断层活动的时间序列,确定其运动速率、频率以及活动断层更多还原

【Abstract】 Nowadays more than 20 kinds of dating methods have been applied to determine Quaternary strata and geological events. Among them radiocarbon dating has been widely accepted for numerical dating the late Quaternary and particularly Holocene geological events. However, high resolution of decades or hundreds years for geological samples and reliable ages of geologic strata chronology are an urgent problem to be resolved which challenges for further studies of geological disaster events. Therefore it is very vital to improve the precision and accuracy of numerical dating methods. This thesis presents a series of experimental results, focusing on two important aspects of radiocarbon dating.1. The performance test of Quantulus-1220 liquid scintillation counter The Chinese Sucrose standard, synthetical benzene and the known ages of dendro-dated tree ring sample were used to assess the performance of Quantulua-1220. The results indicate that:(1) The background is below 0.5 cpm and the fluctuation does not exceed 4‰in the measuring surrounding, thus it is inferred that the maximum datable age for this instrument is expected to reach about 48 Ka BP;(2) The quench calibration curve was established by determining the relative efficiency variety of Chinese Suguar with the quench parameter SQP (E). The experience formula is: C=0.002630040912*X+10.99101753. The quench SQP (E) parameter of 261 radiocarbon samples varies from 700 to 758 in this study. The average value is 735.5 with standard deviation of 9.2. The maximum age error caused by quenching factor is less than 80 years, as calculated from the quench formula;(3) A set of growth rings, up to 45 rings, 60 g weigh, 6.5 cm long, were used to test the reliability of the dating procedure in our lab. This ring sample was dated to be 5458±54 a BP and the calibrated age is 4355 BC (68.2%) 4255 BC, converting in OxCasl 3.10 program. This dating result agrees well with the dendro-dated age of 4249~4294 BC. This proves that the sample pretreatments and its radiocarbon dating results in the laboratory are reliable.2. Radiocarbon dating of different components isolated from paleosol Radiocarbon dating is usually used to estimate the date of paleoearthquakes because the paleosol is ubiquitous in trenches. Five paleosol samples and a piece of pottery were collected from a trench wall at the Shangdalai village, near Tumotezuo county, located in the southern margin fault of the Daqing Mountain, Inner Mongolia. They were dated by radiocarbon dating and thermoluminensence dating, respectively. The更多还原