摘要
暴露岩石中宇生核素的浓度与暴露年代、侵蚀速率相关,暴露年代和侵蚀速率可相互求证,但两者均为未知数时,可求算出最大侵蚀速率和最小暴露年代。据此得出张八岭地区的最大侵蚀速率为7 12m/Ma,最小暴露年代为(85700±1500)a,这一年代远小于统一夷平面的形成年代(7～3 6Ma),造成这种差距的主要原因是:①张八岭地区侵蚀速率大,岩石中宇生核素的浓度较早达到平衡,即达到该地区的测年上限;②采样地区曾被土壤覆盖,造成计算年代值过于年轻。
Because of the production of cosmogenic isotopes, the concentration of cosmogenic isotope in surface layer of the exposed rocks accumulates increasingly, and at the same time, it becomes less and less with isotope radiation and surface erosion. According to this principle and under the condition of cosmogenic isotopes production rate being well known, the correlation between the concentrations of cosmogenic isotopes and time and erosion can be calculated. By means ot this model, we use 10Be in a surface sample of Zhangbaling to calculate the minimum exposure age to be (85 700±1 500)a and the maximum erosion rate to be 712 m/Ma. The time is much shorter than the time when the planation surface was formed(7～36 Ma).The difference is caused by ①the erosion rate here was so large that the concentration of the cosmogenic radionuclide 10Be could reach its steady state much earlier; ②we ignore the inherited 10Be.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2003年第1期77-79,共3页
Marine Geology & Quaternary Geology
基金
教育部"教育振兴计划"青年教师奖励基金资助项目(2001DLXSBJBC12)
江苏教育学院科学研究"十五"规划资助项目
