Geological dates are usually obtained by using the rates of decay of various radioactive elements found in minerals.

地质年代通常是通过矿物中发现的各种放射性元素的衰变率来获得的。

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These minerals can be dated by radioactive decay techniques because of the very small quantities of radioactive trace elements they, in turn, contain.

这些矿物可以用放射性衰变技术测定年代，因为它们所含的放射性微量元素非常少。

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Helium is the by product of millennia of radioactive decay from the elements thorium and uranium.

氦是钍和铀元素数千年放射性衰变的副产品。

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Alpha particles are these helium nuclei, and they are the result of radioactive decay.

阿尔法粒子是氦核，它们是放射性衰变的产物。

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