Abstract.Airborne geophysical anomaly separation using conventional statistics and the fractal/multifractal concentration-area (C-A) method has been applied to the Tark and Avanligh 1:50 000 sheets in NW Iran. The geophysical survey that resulted in the airborne geophysical data was conducted for uranium exploration in both areas. Selected anomalies were further investigated by using surface radiometric data. Firstly, threshold values to define anomalies were determined and compared by means of conventional statistical methods. Several relatively large anomalies were identified with uranium (U) equal to 1.7 eppm and 1.9 eppm in the Tark and Avanligh areas, respectively; locally these U anomalies have magnitudes exceeding 3.5 eppm in both areas. Log-log plots obtained for the C-A method indicate existence of two separate stages of U enrichment, with a major event being the cause of U concentration values above 6.1 and 3.4 eppm in the Tark and Avanligh areas, respectively. These higher intensity anomalies are located in the northwestern part of the Tark and in the southern part of the Avanligh sheets. In both areas, the C-A anomalies were further investigated using ground radiometric data and XRF analysis revealing higher than 150 and 280 ppm U concentration values in the two areas, respectively. Correlation between the anomalies and geological units show that the anomalies are associated with limestone and sandstone units.
The Kehdolan area is located at 20 kilometers to the southeast of Dozdozan Town (Eastern Azarbaijan Province). According to structural geology, volconic rocks are situated in Alborz-Azarbyjan zone, and faults are observed in the same direction to this system with SE-NW trend. The results show that kaolinite alteration trend with Argilic and propylitic veins is the same direction with SW-NE faults in this area. Therefore, these faults with these trends can be considered as the mineralization control for determination of the alterations. Different image processing techniques, such as false color composite (FCC), band ratios, color ratio composite (CRC), principal component analysis (PCA), Crosta technique, supervised spectral angle mapping (SAM), are used for identification of the alteration zones associated with copper mineralization. In this project ASTER data are process and spectral analysis to fit for recognizing intensity and kind of argillic, propylitic, philic, and ETM+ data which are process and to fit for iron oxide and relation to metal mineralization of the area. For recognizing different alterations of the study area, some chemical and mineralogical analysis data from the samples showed that ASTER data and ETM+ data were capable of hydrothermal alteration mapping with copper mineralization. Copper mineralization in the region is in agreement with argillic alteration. SW-NE trending faults controlled the minerali-G. Hajibapir et al. 583 zation process.
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