The crust granites have higher lead isotope ratios and are richer in uranium lead but poorer in thoriumlead.
壳型花岗岩具较高的铅同位素比值和富铀铅贫钍铅的特点；
2
Since the unstable nuclei exist between actinides, including thorium and stable nuclei like lead and bismuth, explosive events such as supernovae are required to produce actinides.