^(10)Be和^(26)Al就地产率与在地表岩石中浓度积累的定量模型

PRODUCTION RATES AND ACCUMULATIONMODELS OF IN-SITU PRPDUCED10Be and26AlIN SURFACE ROCKS

就地产生的１０Ｂｅ和２６Ａｌ是宇宙射线与地表岩石发生核反应而生成的长寿命放射性核素，半衰期分别为１５和０７Ｍａ．它们的地表产率随海拔高度和地磁纬度的不同而变化．在高纬度的海平面，１０Ｂｅ和２６Ａｌ在纯石英中的就地产率分别为６和３６（原子／ｇ）．产率一定时，它们在岩石中的浓度积累将主要取决于样品的暴露条件（埋藏深度和侵蚀速率）和暴露时间．因此，通过测量它们在岩石中的含量，可以定量估计岩石的暴露条件和暴露年龄．本文详细描述了不同暴露情况１０Ｂｅ和２６Ａｌ在岩石中随时间积累的定量模型．

おn situ produced10Be and 26Al are long-life radioactive nuclides produced by the interactions between cosmic rays and rocks,the half-lives are 15 and 07 Ma respectively. The production rates vary at the surface vary with altitude,magnetic latitude for the shielding effects of magnetic field and the atmosphere. At the sea level in the higher latitudes (>60°),the in situ production rates of10Be and 26Al in pure quartz are 6 and 36 atoms/g. yr. respectively. Their contents in rocks are mainly dependent upon the exposure age and exposure conditions (burial depth and erosion rate ) of the samples when the production rates are not varying notably with time. Therefore,it is possible to determine the exposure age and erosion rate of a rock by measuring the 10Be and 26Al concentrations in the rock. The quantitative models of10Be and26Al concentration variation with time for the different exposure cases are described in detail in this paper. 