论文部分内容阅读
天然放射性同位素 U~(238)、U~(235)、Th~(232)衰变后形成稳定产物 Pb~(206)、Pb~(207)、Pb~(208)。因此,准确测定放射性矿物中 U、Th、Pb 及共同位素的含量,就可以根据 Pb/U、Pb/Th 的比例,计算出该矿物的绝对地质年龄。从复杂成分的矿物中析出铅的方法,在文献中记载不多。一般多利用硫酸氢钾熔融,然后用硫酸钡共沉淀,或者用氟氢酸溶解矿样,并以希土元素与铅共沉淀的方法。上述这些方法,铅的析出率都不甚高,只有70—80%,因此必须加入放射性同位素 Pb~(210)作内标来测定铅含量。
The natural radioactive isotopes Pb ~ (206), Pb ~ (207) and Pb ~ (208) formed after the decay of U ~ (238), U ~ (235) and Th ~ (232). Therefore, accurate determination of radioactive mineral U, Th, Pb and isotope content, based on the ratio of Pb / U, Pb / Th, calculate the absolute geological age of the mineral. The method of depositing lead from minerals of complex composition is not much documented in the literature. Generally more use of potassium hydrogen sulfate melting, and then coprecipitation with barium sulfate, or dissolved with hydrofluoric acid mineral sample, and the method of co-precipitation of rare earth elements and lead. These methods, the precipitation rate of lead is not very high, only 70-80%, it is necessary to add the radioactive isotope Pb ~ (210) as an internal standard to determine the lead content.