Abstract: Based on the multifractal theory, the C-A method of Multifractal model is used to study stream sediment geochemical data of 1∶200 000 scale in Nanjing-Zhenjiang copper-polymetallic metallogenic belt, and the regional anomaly lower limit and local anomaly lower limit of the elements are obtained by analyzing area-concentration double logarithmic chart of the ore-forming elements.The research results show that the local anomaly lower limit and the corresponding anomaly area obtained by the C-A method of multifractal model is more reasonable than that obtained by the method of cumulative percentage of 85% and the method of Mean plus 2 times the standard deviation and it is also consistent with the principle of maximum potential rate with minimum area through comparing with the local anomaly lower limit of different methods and comparing with the relationship between mineral and the anomaly area of different methods.The result of multi-phase of mineralization in this region is also recognized by the multifractal theory, and the mineralization potential of Cu, Pb, Zn is adequate, followed by Ag and then Au.

Key words: Multifractal theory, C-A multifractal model, Local anomaly lower limit, Geochemical anomaly, Mineralization potential, Nanjing-Zhenjiang region