Alteration maps processed from the remotely sensed data may contain a large amount of information critical for mineral exploration. An alteration photomap is however not a type of "ready-to-use" data to determination of anomalies and the trends of enrichment required for predicting of mineral resources only if the different components of the digital numbers have been clearly divided. The fractal filtering technique, as recently-developed tool for decomposing different signatures, is able to separate the anomalous values from background and extract frequencies associate with mineralization processes as indirect digital indicators to altered sequences using concentration-area and spectrum-area models respectively. The fractal filter formed by applying the concentration model to the power spectrum of the processed images, often is a group irregularly shaped filters. Applying these types of filters in frequency domain can separate the following the same of similar power-law or fractal property. Being transformed to spatial domain, the corresponding patterns of the separated components can be obtained. In other word, the fractal filter can be applied to decompose the original remotely sensed data into a series of electromagnetic self-similar signatures with distinct scaling range and anisotropic peculiarities. The analysis to the relationships among these decomposed images can provide useful information for the evaluation of alterations and spatial distribution assessments around mineralized formations. This paper briefly introduces the theory of the fractal filtering technique; So it is going on with case study of most important gold-bearing anomaly in Sarigunny area, Kurdistan province, NW of Iran, will be used to illustrate application of this technique to process ETM images for regional determining of the epithermal alteration units within volcanic features as favorite targets of precious metals in the study area.

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Kamoo region (northeast of Isfahan) has an anticline structure with a northwest-southeast trend. The exposed part of this anticline consists of siltstone-sandstone and Jurassic shale, which is located below the Cretaceous formation as an unconformity. Penetration by magmatic masses (dikes) and mineralization events are mainly related to fault systems and fractures in the region and follow the trend of the anticline. In addition, the intensity and variety of alterations are affected by tectonic factors, with alteration and metasomatic haloes having developed next to crushed areas. The alteration process is the main controller of mineral mass grade in the study area; therefore, iron grade in the Kamoo ore has increased by the effects of alteration. The alteration effects include propylitic haloes, iron hydroxides (limonite), and clay mineralization (argillic). The host rock consists of Jurassic shales with siltstone, sandstone, and Cretaceous limestone. Calcareous formations adjacent to granodiorite masses are the main hosts of iron skarns. The results of this study showed that the mineral samples from Kamoo were relatively rich in Light Rare Earth Elements (LREEs); the average La/Yb ratio is about 18.61 and Eu anomaly is between 0.52 and 1.94. Based on the findings of this study, the origin for Kamoo skarn was consistent with the model presented by Meinert, and the region’s mineralization and alteration characteristics correspond to the conditions prevailing in oceanic subduction and back-arc basin environments.

The study area is located 5.5 km north-east of Kamo County and 30 km north-east of Meymeh, Isfahan. Kamo Index comprises an anticline with a northwest-southeast trend, the outcrop of which consists of siltstone-sandstone and Jurassic shale rocks that lie along a cretaceous unit. Based on field studies as well as petrographic and geochemical investigations, mineral assemblages and minerals in the area include chalcopyrite, pyrite, marcasite, and magnetite as primary ores and malachite, bornite, covellite, chalcocite, hematite, goethite, and hydrous iron oxides as secondary ores. The secondary ores have been formed by oxidation and biogenic processes. The primary textures are granular, disseminated, vein-shaped, and layered and the secondary textures are boxed and martitized, shear zones, replacements, and veins. Tectonic, metamorphic, and oxidation factors are involved in the formation of these textures. Due to tectonic activity in this area and the presence of faults, replacement, vein, and shear textures, which have developed after mineralization, are observed. Among alterations, hematite, propylitic, sericitic, limonitic, and kaolinitic are highly prevalent and they are important in the formation of iron deposits. The sub-alkaline granitoids of the region are related to the continental subduction-zone orogenic series. Studies on the decomposed iron samples from Kamo show that most of the samples are in the sub-alkaline series and the chemical and mineralogical composition of the magma derived from this series is calc-alkaline with a large amount of iron. According to mineralogical, lithological, and geochemical evidence and based on isotopic results, Kamo deposit is a skarn-type deposit.