1896年,贝克勒尔(A.H. Becquerel)观察了含铀矿物(如沥青铀矿)能使封闭的照相底片感光,这是X射线产生的作用。随后证明了铀能自然衰变,它以粒子和电磁辐射的形式放出能量(即放射性)。后来放射性衰变成为地质学家确定地球及岩石形成时代的重要手段。
康定杂岩以往被认为是扬子地块太古宇的基底,但近年来的同位素年龄测定结果表明其并不是形成于太古宙。
The complex was traditionally considered as the Archean basement of the Yangtze Block, but recent isotopic dating results indicate that it was not formed in Archean.
因为它是稀有天然放射性同位素钾衰变而产生的,所以可以用来测定十万年以上的岩石年龄和采样。
Because a radioactive form of argon is produced by decay of a naturally occurring radioactive potassium isotope, it can be used to date rocks and samples more than 100,000 years old.
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