1Introduction Due to its special properties and ubiquitous occurrence,zircon can be found in the crust,mantle,lunar rocks,meteorites,etc.And it is the ideal mineral to test the formation age of rocks(Xie et al.,2001).However,zircons are an exceptionally rare component of kimberlites.They have various sources and courses of formation.Zircons crystallized from kimberlitic magma are usually have large sizes and a maximum diameter of20mm was reported.Typically,they have low contents of U and Th,…