The U-Pb concordia-discordia method the most effective and reliable methods that are dating.

It really is specially resistant to heating and events that are metamorphic therefore is very beneficial in stones with complex records. Very often this process is used with the K-Ar plus the isochron that is rb-Sr to unravel a brief history of metamorphic stones, because all these techniques reacts differently to metamorphism and heating. For instance, the U-Pb discordia age might supply the chronilogical age of initial formation associated with the stone, whereas the K-Ar technique, which can be specially responsive to argon loss by heating, might supply the chronilogical age of the latest heating occasion.

A good example of A u-pb discordia age is shown in Figure 5.

This example shows a chronilogical age of 3.56 billion years when it comes to earliest rocks yet found in united states, and a chronilogical age of 1.85 billion years when it comes to heating event experience that is latest by these stones. The K-Ar many years on stones and minerals out of this rematch coffee meets bagel area in southwestern Minnesota also record this 1.85-billion-year warming event.

Figure 5: U-Pb concordia-discordia diagram for nine types of the 3.56 Morton that is billion-year-old Gneiss Minn. After Goldich among others (56).