摘要
双核素稳态侵蚀岛投影是原地生成宇宙成因核素测年技术中判断样品是否具有复杂暴露历史和估计侵蚀速率的常用方法。暴露、侵蚀、埋藏和再暴露的投影图可依据传统核素浓度计算等式利用计算机编程绘出。利用新推出的地表持续抬升与下降过程中样品的核素浓度与生成速率(及加速率)、侵蚀速率及暴露时间的计算等式,对其26 Al/10 Be浓度比值相对于10 Be浓度/10 Be生成速率比值投影分别进行了计算机模拟,发现下降样品的投影可高于或右偏于稳态侵蚀岛,而抬升样品的投影仍然在稳态侵蚀岛内。利用持续地表下降,可以解释已往文献数据中一次性暴露样品投影高于或右偏于稳态侵蚀岛的“不合理”现象,而持续抬升对投影结果的影响类似于侵蚀,因此如果忽略抬升,计算的暴露年龄结果将偏小。
Dual-nuclide steady state erosion island projection is a common method to determine whether samples have complex exposure history(burial),and to estimate the erosion rate in the in situ produced cosmogenic nuclide dating.Projections of exposure,erosion,burial,and re-exposure can be plotted by computer programming according to traditional nuclide concentration and produce rate formulas.Using the new formula of the surface uplift and subsidence,the 26 Al/10 Be concentration ratio relative to the concentration of 10 Be projection is simulated by computer.Results show that the projection of the subsidence sample is higher than or right to the erosion island,while the projection of uplift is still in the steady erosion.Therefore,continuous surface subsidence can explain the“unreasonable”phenomenon that samples with single exposure history will be projected on higher than or right to the steady state erosion island as reported in previous work.Meanwhile,the effect of continual uplift on the projection is similar to erosion,so if ignoring the uplift,the exposure age calculated will be smaller.
作者
黄费新
程杨
李岩
李广伟
董国成
赵亮亮
HUANG Feixin;CHENG Yang;LI Yan;LI Guangwei;DONG Guocheng;ZHAO Liangliang(Research Institute of Mineral Resources,China Metallurgical Geology Bureau,Beijing 101300;School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023;Institute of Earth Environment,Chinese Academy ofSciences,Xi an,Shaanxi 710061;Xi an Accelerator Mass Spectrometry Center,Xi an,Shaanxi 710061)
出处
《地质与勘探》
CAS
CSCD
北大核心
2019年第6期1500-1509,共10页
Geology and Exploration
基金
国家自然科学基金面上项目(编号:41873064)和面上项目(编号:41176166)联合资助
关键词
抬升
下降
原地生成宇宙成因核素
浓度比值投影
稳态侵蚀岛
uplift
subsidence
in situ produced cosmogenic nuclide
concentration ratio projection
steady state erosion island
