Abstract

The aim of this study is to map orogenic gold prospecting areas in the region of Saqez, NW of Iran. In order to achieve this task geological, geochemical and airborne geophysical data are analyzed and integrated using index overlay and fuzzy logic methods. Geological map of Saqez (1:100000 scale) is used to assign lithological weights based on their favo- rability for hosting orogenic Au mineralization. Also a fault density map is produced and assigned based on the structural map which is included in the geological map. For prepa- ring geochemical evidence maps, data from 535 stream sediment samples are examined using Number-Size multifractal method for Au, As, Bi and Hg. The detected thresholds are used to assign the catchment basins of the stream sediment samples. Aeromagnetic data is employed to detect the edges of magnetic anomalies based on an enhanced edge detection method. Extracted lineaments are then converted to a density map and assigned properly. Airborne radiometric data is also used to produce two evidence maps. Potassium count grid independently and K/Th ratio map are employed to distinguish locations with hydrother- mal activity. Finally after integrating evidence maps, new locations with high potentials of Au mineralization are identified considering that the gold indications of the study area (Qolqoleh, Kervian and Ghabaghloujeh) are placed in the first priority of the fuzzy logic prospectivity map.

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