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岩石和矿物具有的同位素比值,如果把它们反映在~(207)pb/~(204)Pb-~(206)Pb/~(204)Pb图上,就会表现出两种类型的趋势:第一种,时代相同的样品,铅同位素成分点沿直线排列;第二种,不同时代的样品点则顺曲线分布,该曲线接近于所描述的放射性衰变的简单规律。
The isotopic ratios of rocks and minerals show two types of trends if they are reflected in the ~ (207) pb / ~ (204) Pb- ~ (206) Pb / ~ (204) Pb maps: A sample of the same age has Pb isotopic composition points arranged in a straight line. The second sample point of different ages follows a curve that is close to the simple law described for radioactive decay.