Study on the K-Ar Dating of Diagenetic Illite in Sedimentary Rock Samples——Question and Discussion

The diagenetic I/S of P-T boundary in Changxing,Zhejiang province was dated using K-Ar method. The results show that the K-Ar ages of pure diagenetic L/S is younger than the age of the P-T boundary.The rea- sons for this result are that(1)the diagenetic illite in mudstone is formed through the sluggish smectite illitiza- tion,and(2)the loss of the radiogenic~(40)Ar exists in the fine clay minerals during the smectite illitization.