Journal of Mining and Metallurgy, 48 A (1) (2012) 1 - 11 # Corresponding author: P_Afzal@azad.ac.ir SEPARATION OF URANIUM ANOMALIES BASED ON GEOPHYSICAL AIRBORNE ANALYSIS BY USING CONCENTRATION-AREA (C-A) FRACTAL MODEL, MAHNESHAN 1:50000 SHEET, NW IRAN Peyman Afzal *#, Afshar Zia Zarifi ** , Sasan Farhadi Khankandi * , Andy Wetherelt *** and Amir Bijan Yasrebi *** * Department of Mining Engineering, South Tehran branch, Islamic Azad University, Tehran, Iran ** Department of Mining Engineering, Lahijan Branch, Islamic Azad University, Lahijan, Iran *** Camborne School of Mines, University of Exeter, Penryn, UK (Received 7 June 2012; Accepted 12 September 2012) Abstract The aim of this study is separation of uranium anomalies based on geophysical airborne data by utilizing the Concentration-Area (C-A) fractal model in Mahneshan 1:50000 sheet, NW Iran. Threshold values for the different anomalies of uranium were computed with the statistical method which shows that uranium anomaly commences from 282.1 eppm. Furthermore, the C-A log-log plot of uranium shows existence of two stages of uranium enrichment in this area. The major enrichment for U starts from 331.1 eppm. High intensity anomalies (>562.3 eppm) in the area are located in the central and northern parts of the area. The comparison between achieved results and fault’s position patterns shows a positive correlation between uranium anomalies and the faults system in the area. However, mica-schists host high intensive uranium anomalies in the central part of the area. Results analyzed by the C–A fractal model certify that the interpreted anomalies based on the fractal model are accurate in comparison with the chemical analysis of lithogeochemical samples collected from the geophysical airborne anomalies. Key words: Concentration-Area (C-A) fractal model; Uranium; Airborne geophysical data; Mahneshan; Iran. 1. Introduction Airborne geophysical data especially radiometric data are used for identification of radioactive anomalies specifically for uranium exploration. Interpretation of this data is important for mineral exploration specifically radioactive elements [1, 2]. Several methods and models have been used for interpretation of radiometric airborne data [3, 4, 5]. Statistical methods are commonly utilised to identify uranium J o u r n a l o f M i n i n g a n d M e t a l l u r g y