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对燕山地区蓟县剖面铁岭组条带状燧石进行Ar - Ar 阶段加热实验,获得一个马鞍形年龄谱。通过对各温度阶段K、Ca 、Cl 质量分数及Cl/K、Ca/K 比值变化特征的分析,笔者认为马鞍形谱线左侧视年龄的变化与燧石中流体包裹体含过剩Ar 有直接关系;而右侧的变化则与燧石晶格中过剩Ar 的释放有关。马鞍形谱线往往意味着样品含过剩Ar;但含过剩Ar 的样品不一定都呈马鞍形。当燧石纯度很高,加热阶段划分得很细时,马鞍形谱线中温区间最小视年龄具有某种年代学意义。
The Argon - Ar stage heating experiment was carried out on Tieling Formation banded flint in Jixian section of Yanshan area to obtain a saddle - shaped age spectrum. Based on the analysis of the change of K, Ca, Cl and Cl / K, Ca / K ratio in each temperature stage, the author thinks that the change of the left side of the saddle-shaped line is related to the excess Ar in fluid inclusions in chert ; While the change on the right is related to the release of excess Ar in the chert lattice. The saddle line often means that the sample contains excess Ar; however, samples with excess Ar are not necessarily saddle-shaped. When the flint is of high purity and the heating stage is finely graded, the minimum age of the saddle-shaped spectral line has some chronological significance.