CL and FTIR analysis on the diamonds in Wafangdian, Liaoning Province

The CL images show that the internal structures of the diamonds in Wafangdian, Liaoning Province is classified as three types: simple growth girdle zone, multi-stage growth complex girdle zone, and rare agate-like structure. These internal features reflect the complexity of growth processes of the diamonds. The FTIR analyses in micro area on diamond plates reveal the heterogeneity of the impurities of nitrogen and hydrogen. The variety of nitrogen contents and nitrogen aggregation states have been revealed not only in different diamonds from one kimberlite pipe but also in different zones of one diamond. The extent of conversion A defects to the aggregated B form is a function of the nitrogen aggregation temperature (T_NA), mantle residence time (t_MR), and nitrogen concentration of diamond. The interval of0.6-0.7Ga from core to rim of diamond growth is obtained by using the FTIR curves and some geological data. The long period of diamond growth is identical with the feature in CL image.