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锕系核素~(232)Th、~(235)U、~(238)U和~(244)Pu对太阳系年代学和银河系“宇宙年代学”具有重要的意义,因为太阳系中锕系元素的平均丰度取决于太阳系形成之前银河系中r过程核合成的性质。1970年以前,一般假定陨石中锕系元素的化学分馏不明显,特别是球粒陨石,在全岩范围内其难熔亲石元素的分馏较小。然而现在证明这种假设是错误的,现讨论如下。
Actinides ~ (232) Th, ~ (235) U, ~ (238) U and ~ (244) Pu are of great importance for solar system chronology and galactic “chronology.” Because the actinides The average abundance depends on the nature of the r-process nuclear synthesis in the galaxy prior to the formation of the solar system. Before 1970, it was generally assumed that there was no obvious chemical fractionation of actinides in meteorites, especially chondrites. Fractionation of refractory pegmatites was less in the whole rock. However, it is wrong to prove this assumption now, and the discussion is as follows.