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如果将Stacey和Kramers(1975)或Cumming和Richards(1975)的模型作为计算模型年龄的基础,那么加拿大科迪勒拉(图1)古生代页岩型矿床的方铅矿-铅同位素(表2)将给出不真实的年轻的年龄。可是,赫利克到泥盆-密西西比期矿床的这些相同的同位素数据在图2和图3的~(208)Pb/~(204)Pb-~(206)Pb/~(204)Pb或~(207)Pb/~(204)Pb-~(206)Pb/~(204)Pb图上却形成独特的组,并且按年龄形成有规律的排列。页岩型矿床(图1)中所有这些同位素数据以这样一种方式作图,是为了表明类似地壳
If the models of Stacey and Kramers (1975) or Cumming and Richards (1975) are used as the basis for calculating the age of the model, the galena-Pb isotopes of the Paleozoic shale deposits in Cordillera, Canada (Figure 1) Will give unrealistic young age. However, these same isotope data from the Hurlik to Devonian-Mississippi deposits are shown in Fig. 2 and Fig. 3 at 208 Pb / 204 Pb- 206 Pb / 204 Pb or ~ 207) Pb / ~ (204) Pb- ~ (206) Pb / ~ (204) Pb shows the formation of a unique group, and the formation of a regular order by age. All of these isotopic data in shale deposits (Figure 1) are plotted in such a way as to indicate that similar crust