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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。
The concentration of the nuclide in the exposed rock is related to the age of exposure and the erosion rate. The exposure age and the erosion rate can be verified with each other. However, when both are unknown, the maximum erosion rate and the minimum exposure time can be calculated. It is concluded that the maximum erosion rate in Zhangbaling area is 712m / Ma and the minimum exposure time is (85700 ± 1500) a, which is much smaller than the formation age of the unified flat surface (7 ~ 36Ma) The main reasons are as follows: (1) The erosion rate in Zhangbaling area is large and the concentration of the nuclide in the rock equilibrates earlier, reaching the upper limit of the year in the area; (2) The sampling area has been covered with soil, resulting in the calculated age value being too young.