摘要
精确、可靠测定古土壤和生物化石年代是重建环境变化过程、探讨人地关系的关键.研究古土壤中不同组分年代的异同对于分析土壤中碳附存状态和碳储存库十分重要.对甘肃省榆中县境内兴隆山典型黄土剖面采集的动物化石、土壤无机质、土壤有机质3个样品进行常规14C和AMS测年,发现同一地层相同点样品不同组分的测年结果相差悬殊,样品无机质比其有机质年龄(3682±70)a偏老2624a.对其14C测年可靠性对比分析发现,常规14C和AMS对骨骼和牙齿化石测年相差仅为13a,校正为日历年后几乎相等,认为实验室产生的误差很小,而碳的来源、组成及其“死碳”混入的比例是影响测年结果的主要因素.化石年龄与土壤有机质年龄之间的差别,揭示该剖面可能存在持续时间达千年以上的沉积间断.由于同一层位骨化石、土壤有机质、土壤无机质14C测年结果差异,在进行化石年代确定、考古及古文明研究、生态植被恢复、土壤无机碳存储库研究中,年龄的界定应选择相应的测年数据.
Dating paleosol and animal remains accurately and reliably is of crucial importance in reconstructing environmental change processes and researching the relationship between natural environments and human evolution. Dating different components in the same specimen and differentiating their ages is also important for tackling problems such as carbon storage state and soil carbon sources. Conventional ^14C and AMS dating on animal remains （fossil bone and teeth） and inorganic and organic soil matter from a typical loess section at Xinglong Mountain, Yuzhong County, Gansu Province reveal that three different substances in the specimen from the same sampling position possess different ^14C ages： the age of inorganic matter is 2 624 years older than that of organic matter, which is dated at （3 682±70）a. According to the reliability analysis of these 14 C ages, laboratory error is negligible, but the 14 C resources, the component of ^14C and the proportion of “dead carbon” are the main factors influencing 14^ C dating results. It is only possible to date the geological events correctly and reliably by analyzing the reasons generating these differences and the age comparison of different substances may provide information on paleoclimate and paleoenvironmenL A 2 000 year difference between the 14^C ages of fossil and organic soil maner might indicate that a sedimem gap exists, which is very important when reconstructing paleoclimate by loess section.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2005年第5期589-596,共8页
Earth Science-Journal of China University of Geosciences
基金
国家自然科学基金项目(No.40371117)
中国科学院"百人计划"
中国科学院西安地球环境研究所黄土与第四纪地质国家重点实验室基金项目(SKLLQG0514).
