Abstract: To limit the diagenetic age of quartz diorite in the crypto-explosion breccia of the Dechang Dalucao in Sichuan Province, LA-ICP-MS zircon U-Pb chronology was carried out. The results show that the LA-ICP-MS U-Pb age of the Dalucao quartz diorite zircon is (751.7±4.6) Ma (n=39), indicating that the diagenetic age is Neoproterozoic, which is similar to the formation age of a large number of medium acid intrusions and volcanic rocks in the western and northern margins of the Yangtze Block. The Dalucao crypto-explosion breccia was formed in the shallow part of the crust, which provided a channel and favorable preservation conditions for the formation of rare earth deposits, suggesting that the deep part of the Dalucao has great potential for rare earth prospecting.