فصلنامه زمین شناسی اقتصادی
سال دهم شماره 1 (پیاپی 18، بهار و تابستان 1397)

Kuh Zar Au-Cu deposit is located in the central part of the Torud-Chah Shirin Volcanic-Plutonic Belt, 100 km southeast of the city of Damghan. Mineralization including quartz-base metal veins are common throughout this Cenozoic volcano-plutonic belt (Liaghat et al., 2008; Mehrabi and Ghasemi Siani, 2010). The major part of the study area is covered with Cenozoic pyroclastic and volcanic rocks that are intruded by subvolcanic rocks. This paper aims to study the geological, geochemical and petrogenesis of the area using exploration keys for new mineral deposits in the Torud-Chah Shirin zone.

To better understand the geological units and identify the alteration zones of the area, 200 rock samples were collected from the field and 132 thin sections with 15 polished thin sections were prepared for petrography and mineralization studies. Ten samples of intrusions with the least alteration were analyzed using the XRF at the East Amethyst Laboratory in Mashhad, Iran. These samples were also analyzed for trace and rare earth elements using ICP-MS, following a lithium metaborate/tetraborate fusion in the Acme Analytical Laboratories Ltd, Vancouver, Canada. 137 geochemistry samples were prepared by the chip composite method of alteration and mineralization zones and were analyzed in the Acme laboratory by Aqua Regia AQ250.

The geology of the area consists of pyroclastic (crystal tuff) and volcanic rocks with andesite and latite composition, which were intruded by subvolcanic intrusive rocks with porphyritic texture and monzonitic composition. Monzonite rocks were intruded by younger subvolcanic units with dioritic composition. The intrusion of monzonitic pluton and stocks led to the formation of QSP, propylitic, carbonate and silicification-tourmaline broad alteration zones in the area. Monzonite rocks accompanied with disseminated mineralization of about 1 to 10% of pyrite and these sulfides have been converted to secondary iron oxides such as goethite, hematite and limonite. Lithogeochemical exploration revealed Au (up to 598 ppb), Ag (up to 3747 ppb), Cu (up to 679 ppm), Pb (up to 1427 ppm) and Zn (up to 1013 ppm) anomalies. Based on geochemical studies, intrusive rocks have characteristics of high-K Calc-alkaline to slightly shoshonitic and they are within metaluminous to the slightly peraluminous range. Enrichment of LREE versus HREE, enrichment of LILE and depletion in HFSE indicate that the magma was formed in the subduction zones. The negative Eu anomaly is due to the presence of plagioclase as a residual mineral in the magma source. The parent magma is probably formed by the partial melting of amphibolites. The presence of monzonite porphyry source rock, QSP and propylitic alterations, pyrite disseminated mineralization and geochemical anomalies of Au and Cu in the Kuh Zar deposit represents Au-Cu porphyry mineralization in the area.

Tectonic setting discrimination diagrams (Pearce et al., 1984) show that subvolcanic rocks plot almost on the fields of the volcanic arc granites (VAG). In the Rb/Zr vs. Nb diagram from (Brown et al., 1984), the samples are plotted in the field of primitive island arc/continental margin arc. The Torud-Chah Shirin Belt is a part of the Alborz magmatic assemblage (AMA). The AMA has been interpreted to represent the subduction of the Neo Tethyan oceanic lithosphere beneath the Central Iranian continental microplate and the subsequent continental collision of the Arabian and Iranian microplates in the late Cretaceous-early Cenozoic (Berberian and Berberian, 1981; Berberian et al., 1982; Alavi, 1994; Golonka, 2004).
Acknowledgement: This study has been supported by the Research Foundation of the Ferdowsi University of Mashhad, Iran (Project No. 27126.3). The authors would like to acknowledge the East Amethyst Laboratory for XRF analysis. We also thank the Gold Company of Iran for providing conditions for camping and accommodation.

The study area includes Alam Baghi, Vashaghan, Sar Band and Ghermez Cheshmeh and is located in the northeast of Farmahin and the southwest of Tafresh. Based on the structural subdivisions of Iran, the mentioned area is a part of Central Iran and the Urumieh-Dokhtar magmatic belt (Hajian, 1970).
The studied volcanic rocks consist of trachybasalt, trachyandesite, basaltic andesite, andesite, dacite, rhyodacite, rhyolite, ignimbrite, tuff and tuffit in composition and in terms of age they belong to the middle and upper Eocene. It seems that the volcanic activities are related to folding and faulting in the studied area. On the other hand, in addition to causing orogenic activity, at the middle and upper Eocene (Ghasemi and Talbot, 2006), locally extensional regime has played a main role in volcanic eruption. Similar to this scenario happened in other areas such as Taft and Khizrabad in Central Iran (Zarei Sahamieh et al., 2008). Porphyritic, microlite porphyritic and microlitic are the main textures in these rocks. Mineralogically, they contain plagioclase, clinopyroxene, amphibole, quartz and biotite as the main minerals and zircon, apatite, and opaque minerals as accessories.
The major and trace elements of mineral composition are determined by electron probe micro-analysis (EPMA) using a Cameca SX100 instrument in the Iran Mineral Processing Research Center (IMPRC). Moreover, the whole-rock major and some trace elements analyses for a few samples were obtained by X-ray fluorescence (XRF), using an ARL Advant-XP automated X-ray spectrometer.
Based on EPMA analyses, plagioclase mineral in basaltic andesite and trachybasalt samples range from labradorite to bytownite in andesite and trachyandesite has oligoclase- andesine and in dacite, rhyodacite, rhyolite has an albite-oligoclase composition. In the Wo-En-Fs diagram, all clinopyroxenes show augitic and a lessor amount of clinoenstatite composition and in the Q-J diagram located in the Mg-Fe-Ca (Quad) field and in the 2Tiિ肕 vs. Naɒ diagram (Morimoto et al., 1988) located above on the Fe3=0 line that indicate high oxygen fugacity during crystallization. Microscopic study on these rocks such as oscillatory zoning, resorption rims in plagioclase and the presence of basic inclusions suggest the occurrence of magmatic contamination on the parent magma. The presence of oxidized amfibool rims (in hornbelende as oxy hornbelende) indicate the high temperature of the magma at the time of eruption.
According to the classification diagrams such as total alkaline vs. SiO2 (Irvine and Baragar, 1971) TAS (Le Bas et al., 1986) and tectonic discrimination diagrams (Pearce et al., 1984) samples are plotted in sub-alkaline, basaltic-andesite, andesite, dacite and rhyodacite, subduction and volcanic arc fields, respectively.
The geochemical diagrams such as AFM are used for the identification of magma series and show that the studied rocks are calc-alkaline and A/NK vs. The A/CNK diagram shows the metaluminous to peraluminous nature. Incompatible and LIL elements such as Ba, K and Rb enrichment show that the contamination of magma with continental crust has occurred. The similarity between the REE patterns in all of the collected samples in Alam Baghi, Vashaghan, Sarban and Ghermez Cheshmeh areas suggest the same source for all of the volcanic rocks.
The tectonic setting diagrams show that these rocks belong to the continental margin which has been involved in a subduction zone.
The position of the samples on the major elements vs. SiO2 diagrams indicate that magma differentiation has occurred. Spider diagrams show a positive anomalous in Rb and a negative anomalous in Nb and Ti This phenomenon shows a contamination between the magma and the crustal rocks (Rollinson, 1993). Also, MORB-normalized incompatible element patterns of the Farmahin area show that the parent magma has been contaminated. It appears that assimilation and fractional crystallization (AFC) were the dominant processes in the genesis of the studied volcanic rocks.
As a conclusion and according to field evidence and geochemical characteristics presented in this article, the studied area is composed of lava flows and pyroclastic rocks such as andesite, dacite, rhyodacite, ignimbrite, tuff and tuffits that cross cut by younger dykes and belong to the middle to late Eocene age (middle to upper Lutetien). According to Sm/Yb vs. Sm diagram (Aldanmaz et al., 2000), all the studied samples in terms of composition are similar to enriched mantle-derived melts that are generated by varying degrees of partial melting (10% - 20%) from a spinel lherzolite to spinel-garnet lherzolite source.
Considering the evidences, all rocks in the studied area belong to the subduction zone and the parent magma originated from mantle and was contaminated with continental crust during eruption and rising.
Acknowledgments: The authors wish to thank the Journal Manager and reviewers who critically reviewed the manuscript and made valuable suggestions for its improvement.

Using stream sediment geochemical exploration has been considered as a useful approach to explore the good potentials for many years. Problems might come up in the course of implementing resolving which may requires the use of more recent findings or auxiliary methods.
One of the areas which has faced special problems during the conducting geochemical exploration is the Orzooiyeh region on the border of Kerman and Hormozgan provinces. Stream sediment exploration was carried out in the area in the scale of 1: 100,000. This region includes two different geological zones that are the Sanandaj-Sirjan in the northern part and the Zagros in the southern part. During the statistical analysis and method of eliminating the effects of the upstream rock it was determined that most of the element of chromium’s anomalies are in compliance with the Bakhtiari and Aghajari units which are lacking in the economic importance in the chromium ore. Current geochemical exploration methods often extract the anomalies based on classical statistical methods (Yazdi, 2002). In these methods, the range of the anomaly is just determined based on simple numerical calculations and except for grade, any of the other parameters do not have a significant role in determining the anomaly areas. However, procedures such as fuzzy logic, neural system, regression and hierarchical analysis process enable the users to involve more parameters in data processing (Oh and Lee, 2010; Kumar and Hassan, 2013; Carranza, 2008).
For instance, using special algorithms has made parameters such as lithology and tectonic, geophysics and geochemistry effective in processing and determining the anomaly zones, and ranking each of the affective parameters in the anomaly based on their importance, and eventually achieving the maps and valuable anomaly areas possible (Bonham-carter, 1994; Carranza, 2008).
This study was conducted to identify the significant anomalies zones using AHP and GIS techniques.

AHP (Analytical Hierarchy Process) is the most comprehensive system designed for multi-criteria decision-making. This method was offered firstly by Sati in 1980, and has carried out numerous applications in different sciences until now. This technique also shows the consistency and inconsistency of the decision that is the outstanding benefit of this technique in multi-criteria decision-making and has been proposed for complex and fuzzy problems based on human brain analysis, and consists of three stages: basic, involving the creation of a hierarchy, determining priorities and logical consistency (Macharis et al., 2004).
In AHP, the factors are compared with each other in pairs and the highest weight is given to the layer that makes the maximum impact on determining the goal (Carranza, 2008). So in this research, after the detection of the effective factors in determining the anomaly areas in the study area, the factors have been weighed for prioritizing the criteria in their order of importance and the paired comparison matrix is formed based on the characteristics of the area and comparative studies for criteria and sub-criteria. After the formation of paired comparison matrices using approximate arithmetic average, the relative weight of parameters was calculated. Then, the researcher carried out the various stages of preparing and the extracting data layer deals with each of these factors in the GIS environment and finally the layers were integrated with each other and the entire range of the anomaly was ranked based on appropriate models.

The results of calculating the final weight criteria show that among the study groups, groups Geochemistry .0.45, lithology 0.45 and tectonic 0.1, respectively, are more significant. The ratio of consistency between these groups is 0.02 and is acceptable and the map prepared by the integration of these groups in the GIS environment according to calculated weights shows that a significant proportion of the false anomalies in the region have been eliminated, and the chromium anomalies associated with ophiolites and peridotites of the region show their best. Therefore, this method can be used for providing the mineral prospecting map that the abandoned mines located in the upstream of anomaly areas confirmed the efficiency of this method in the determination of the anomaly areas.

In the present study, the hierarchical process analysis method was utilized to eliminate the false anomalies caused by small and non-significant placer deposits related to the detrital formations in the region. The effective factors in determining the anomaly zones were determined and the final map was constructed by integrating groups, lithology, elemental geochemistry and tectonics that is, the anomaly zones map was drawn in the GIS environment. The results show that the region anomalies are related to ophiolite and ultrabasic and a little bit the region detrital. Therefore, a significant percentage of false anomalies associated with the regional detrital of the area was eliminated by this method and the real anomalies showed their best. This discussion indicates the efficacy of the method of AHP and GIS technique, and they can be considered to be effective methods to reduce the impact of Singenetic factors and naturally to eliminate false anomalies.

Chemical and textural zoning patterns preserved in plagioclase phenocrysts can provide useful information on parameters that constrains the changing melt compositions in the magma systems. Many studies have utilized the compositional and textural information recorded in plagioclase from igneous rocks to infer the various aspects of magma chamber dynamics and the source of copper in the copper deposits (Viccaro et al., 2010). The Zafarqand porphyry copper deposit is located at the center of the Urumieh-Dokhtar magmatic arc and is mainly composed of Eocene volcanic and sub volcanic rocks, which were intruded by Miocene granodiorite. Alteration and mineralization in this area are superimposed onto the associated porphyritic body and the surrounding country rock (Aminoroayaei Yamini et al., 2016). In this paper, the growth of the plagioclase crystals in the magma is simulated on the basis of various microtextures and their profile composition. Magma mixing, magma recharge phenomenon, and the source of copper are also examined in this area.

A total of 200 samples were collected by the variation of lithology from the volcano-plutonic unit of Zafarqand. About 60 thin sections were made and petrographic observations were carried out using a polarizing microscope. The major-element compositions of plagioclase were analyzed at EPMA Laboratories of Naruto University in Japan and the University of Oklahoma. For analyses, an accelerating voltage of 15 kV, a beam current of 20 nA, and 20s counting time was used. The EPMA data obtained from some representative samples are shown in Tables 2 and 3.

Plagioclase is the most abundant phenocryst phase in Zafarqand plutonic rocks. Based on their textures, plagioclases found in the host granodiorites fall into three populations. The most common population consists of medium grains that have oscillatory zoning. However, synneusis texture is shown in this rock. Granodiorite plagioclase phenocrysts exhibit strong resorption zones and are composed of profuse network micron-sized glass inclusions.
Plagioclases from andesitic dyke also fall into two populations: Plagioclase microlites and phenocryst grains. Phenocryst grains commonly have coarsely sieved interiors resulting from the presence of an extensive network of interconnecting inclusions that pervade the crystal periphery with oscillatory zoning.
In many rhyodacites, plagioclase phenocrysts appear broken as evidenced by their cracked morphology. Resorption surfaces are the horizons, like an unconformity surface mark a boundary between the other phases.

The magmatism of the “Zafarqand” district is often typified by the occurrence of mafic enclaves (cognate xenoliths) indicative of comagmatism and geochemical mixing trends (Aminoroayaei Yamini et al., 2016). This area corresponds to an intrusion that would be linked to a subduction-related geodynamic context. The overall similarity in the REE patterns of the volcano-plutonic rocks exhibits a common source and same geological features for them but different age (Aminoroayaei Yamini et al., 2016).
However, from the plagioclase textural observations a simplified magma plumbing model is envisaged for the studied crystals. At the initial stage, water saturated high temperature magmas have undergone extensive crystallization at lower-crustal chamber depth (Deeper MASH Zone) where optically clear An-rich plagioclase is produced. When this crystal-rich magma ascends to shallow depths, the crystals have undergone varying rates of dissolution that causes the development of CS morphologies. Variation in dissolution intensity may be due to differences in the rate of decompression or H2O content dissolved in the magma (Viccaro et al., 2010). The crust chamber was dynamically active by the input of Shallow MASH Zone pulses. Consequently, the growth of both pre-existing and newly brought crystals was constrained by the heterogeneous superheating and convection processes. As a result, they developed OZ and RS textures. Dissolution happens during magma mixing. However, the presence of microgranolar mafic enclaves and OZ texture in granodiorite from Zafarqand precludes the possibility of end-member magma mixing in these rocks. Thus, RS is the result of superheating and intense dissolution by mafic magma recharge event. Such recharge events could be like a cryptic-mixing process in which the magma chamber experiences repeated addition of small pulses of primitive and hotter and more mafic magma with different ƒ(O2) or H2O contents (Ginibre et al., 2002). After the recharge event, the pre-existing crystals in the crust chamber interacted with new magma causing intense dissolution in the form of RS morphology. In addition to the heating and intense dissolution, crystals in the crust chamber also experienced repeated movements across the magmatic gradients by convection or turbulence as evidenced from the OZ domains in the plagioclase (Ginibre et al., 2002). Then, the magma chamber might have experienced under-cooling by degassing or water exsolution followed by violent aerial eruption producing microlites, broken crystals. The occurrence of sulfide melt in the grandmas of biotite and amphyole phenocrists, mafic enclaves and magma mixing feature, suggests that, similar to the Bajo de la Alumbrera deposit, the injection of more mafic magma may also contribute a large amount of ore metal to the magma chamber and generate Cu mineralization at the Zafarqand deposit.

In the regional prospecting of ore minerals, geologists usually utilize remote sensing images for hydrothermal alteration mineral mapping as a kind of lithological anomaly, which may be linked to mineral deposits (Carranza, 2002).
Compared to the multispectral remote sensing images, composed of few spectral bands, the hyperspectral data prepare much more spectral details of the surface materials in many bands. These high spectral resolution images provide subtle spectral data for identifying similar materials of the surface (Camps-Valls et al., 2014). This ability could greatly promote the potential of hyperspectral based mineral mapping (Wang and Zheng, 2010). As in the two last decades, hyperspectral remote sensing has been an important tool for studying earth’s minerals and rocks (Zhang and Peijun, 2014).
Although, the high number of spectral bands is an important advantage for hyperspectral images, many of those bands are usually irrelevant and redundant and, therefore, cause just the size and complexity of the band space to be increased. This complexity can lead to an ill-posed problem in supervised classification, namely the curse of dimensionality and the Hughes phenomenon, which negatively affect the accuracy of the classification (Camps-Valls, 2014).
Feature reduction methods can be applied to overcome these problems and to eliminate those spectral bands in the classification of hyperspectral images that provide no further useful information. These methods produce an efficient subset of features (spectral bands in remote sensing field) from the original feature space. The decrease in complexity obtained as a result of the feature space reduction can increase the ability of classifiers to efficiently capture the classification rules. Consequently, the speed, generalization, and predictive classification accuracy are increased (Gheyas and Smith, 2010; Camps-Valls et al., 2014).
This study is aimed at evaluation and management of the curse of dimensionality risk in hyper spectral data classification by means of a feature reduction method. The method is utilized to select more informative spectral bands of Hyperion hyperspectral data, which are more effective for the classification of hydrothermal alteration zones. The well-known study area here is the Darrehzar porphyry copper mine located 8 km from the southeast of the giant Sarcheshmeh mine.

1. Hyperion data
The Hyperion hyperspectral image with 242 spectral bands acquired on July 26, 2004 was available and it was used in this study.
2. Train and test datasets
Two datasets were utilized. The first dataset that resulted from the Mixture Tuned Matched Filtering (MTMF) method was applied to feed the feature reduction method and the second dataset containing 17 rock samples collected from the study area was used to carry out the classification by SVM.
3. The feature reduction

In this study, we applied a hybrid Feature Subset Selection (FSS) method to reduce the number of spectral bands of Hyperion data. Extensive details may be found in Moradkhani et al. (2015).
Discussion and

The Feature Subset Selection (FSS) algorithm was applied to reduce the size of the spectral bands of Hyperion data. The implementation of this algorithm resulted in the selection of 9 bands among all 165 spectral bands (i.e. 5% of all useable spectral bands of Hyperion) as the more influential bands for the identification of clay minerals. These bands belong to the two spectral ranges, 2125-2250 nm and 2250-2400 nm, respectively. On the other hand, it is believed that the Short-Wave Infrared (SWIR) electromagnetic range (2000-2500 nm) is an important spectral range for distinguishing clay minerals of the hydrothermal alteration systems (Hosseinjani Zadeh et al., 2014). This implies that two ranges introduced by FSS were accurately selected, because both of them coincide with the SWIR range. Clearly speaking, bands 201, 202, 204, and 205 in the range of 2125-2250 nm are used for muskovit, kaolinit and alunit enhancement. Moreover, bands 217, 220, 222, 223, and 224 in the 2250-2400 nm are appropriate for chlorite classification.
A comparison between the maps of SVM based classification of the alteration zones using 9 (selected by feature selection method) and 165 (all useable bands of Hyperion data) spectral bands confirmed a significant improvement in the output results when 9 more informative bands are utilized for classification instead of all 165 bands. In fact, the classification based on 9 selected bands is comparable and even more effective than the full band classification. This is because the decrease in spectral bands makes SVM learn the rules of classification more accurately.

The Kolah-Ghazi granitoid assemblage is located in the south of Esfahan and in the Sanandaj-Sirjan magmatic-metamorphic zone. The Sanandaj-Sirjan zone is extended for 1500 km from Sirjan in the southeast to Sanandaj in the northwest of Iran and is situated in the west of Central Iranian terrane.
The Sanandaj-Sirjan zone represents the metamorphic belt of the Zagros orogeny which is part of the Alpine- Himalayan orogenic belt. The Kolah-Ghazi granitoid assemblage consists of granodiorite, granites, quartz-rich granitoid and minor tonalite. The aim of this paper is to represent the mineralogy, geochemistry, petrogenesis and tectonic setting of this plutonic assemblage.

More than 60 samples representing all of the rock units in the study area were chosen for microscopic studies. Then, 22 samples were selected for geochemical studies. The major elements were determined with XRF in the Naruto University, Japan. The trace and rare earth elements were analyzed by ICP-MS in the Acmelab, Canada. The geochemical results are presented in Table 1.

The Kolah-Ghazi granitoid assemblage intruded into the Jurassic sedimentary units and overlaid by lower Cretaceous sandstone and conglomerate which suggest Upper Jurassic as the possible age of the Kolah-Ghazi intrusion. Based on the modal studies, this granitoid assemblage is comprised of granite, granodiorite, quartz-rock granitoid and tonalite with different igneous textures including symplectic, myrmekitic, rapakivi, poikilitic and porphyroid. There are some xenoliths, microgranular enclaves and sur micaceous enclaves in the Kolah-Ghazi granitoid assemblage. Xenoliths are mostly derived from Jurassic shale and sandstones which have been trapped in the magma. The sur micaceousenclaves have tonalite composition. The sur micaceous enclaves are biotite-rich rock fragments which display metamorphic texture. The sur micaceous enclaves are classified as restite since they are poor in quartz. The essential minerals in this magmatic assemblage are quartz, plagioclase, alkali-feldspar and biotite as the only ferromagnesian mineral. There was no hornblende in the studied samples. The presence of andalusite, sillimanite and garnet in these rocks point to the sedimentary source of these granitoid melts. Zircon, apatite and opaque minerals occurred as accessory minerals. The secondary minerals included sphene, tourmaline, clay minerals, chlorite and opaque minerals. The Kolah-Ghazi rock samples plot on the granite and granodiorite fields on the geochemical classification diagrams. The geochemistry of these plutonic rocks show peralunimous, high K-calc alkaline features. On the Harker variation diagrams, it can be observed that the Al2O3, FeO, MgO, TiO2 and CaO contents decrease with the increase in SiO2, whereas K2O and Na2O show an ascending trend with increasing SiO2. Moreover, the fractionation of plagioclase and the crystallization of alkali-feldspar caused the observed trends of Rb and Sr in the Harker diagrams. Ba contents decrease with increasing SiO2 which is relevant to the biotite fractionation. All of the analyzed samples show similar patterns in the chondrite-normalized trace elements and the REE diagrams. All samples show LILE and LREE enrichment and HFSE and HREE depletion. The negative anomaly of Sr may be related to the lack of calcic-plagioclase in these samples or suggest the plagioclase rich restite during partial melting of the parental rock. The latter is in agreement with the Eu anomaly that appeared in the REE diagram. All of the Kolah-Ghazi samples show linear trends in the major and trace elements versus SiO2 diagrams and display similar REE patterns suggesting close relationship in the source and magmatic history.
The field, petrography and geochemical evidences such as pegmatit veins in the pluton, biotite rich enclaves, lack of hornblende and titanite, occurrence of metamorphic minerals (e.g., garnet, andalusite and sillimanite), the predominance of ilmenite, A/CNK values (A/CNK >1), and crondom contents (more than 3% in norm) suggest that the Kolah-Ghazi plutonic assemblage can be classified as S-type granitoids. Moreover, all of the Kolah-Ghazi samples plot on the S-type field of the granite classification diagrams (Whalen et al., 1987; Chappell and White, 1992) which is in good agreement with mineralogical evidences.
The sedimentary source, mostly shale and greywacke, can be suggested for Kolah-Ghazi melts according to the Rb/Sr vs. Rb/Ba diagram (Sylvester, 1998). Several discrimination diagrams such as Rb vs. Ta (Pearce et al., 1984) and R1-R2 (Batchelor and Bowden, 1985) were used to determine the tectonic setting of the Kolah-Ghazi granitoids. The Kolah-Ghazi samples lied between the fields of magmatic arc and syn-collisional granitoids in the discrimination diagrams.
The geochemistry of the studied samples suggest a syntectonic environment for the Kolah-Ghazi granitoids which may be related to the late Cimmerian orogenic phase.

The Hamech prospect area is located in the eastern Iran, 85 kilometers southwest of Birjand. The study area coordinates between 58¬¬˚¬53΄¬00 ˝ to 59˚¬00΄¬00˝ latitude and 32˚¬22΄¬30 ˝ to 32˚¬26΄¬00˝ longitude. Due to the high volume of magmatism and the presence of geo-structure special condition in the Lut Block at a different time, a variety of metal (copper, lead, zinc, gold, etc.) and non-metallic mineralization has been formed (Karimpour et al., 2012). The studied area (Hamech) includes Paleocene-Eocene igneous outcrops which contain a wide range of subvolcanic bodies (diorite to monzonite porphyry) associated with mafic intrusives, volcanic units (andesite), volcaniclastic and sedimentary rocks.
Material and This study was done in two parts including field and laboratory works. Sampling and structural studies were done during field work. Geological and alteration maps for the study area were also prepared. 200 thin and 60 polished sections for petrographic purpose were studied. The number of 200 thin sections and 60 polished sections were prepared and studied in order to investigate petrography and mineralogy. Major oxides (XRF method- East Amethyst Laboratory in Mashhad), rare earth elements and trace (ICP-MS method-ACME Laboratory in Vancouver, Canada) elements were analyzed for 13 samples that included subvolcanic units and intrusive bodies. Data processing and geological and alteration mapping is done by the GCD.kit and Arcgis software.
Discussion and Based on lab work and XRF analysis, the rocks in the area are composed of intrusive-subvolcanic bodies and volcanic rocks (andesite, trachyandesite and dacite) together with volcano-classic and sedimentary rocks. Also, alteration zones consist of a variety of argillic, silicified, quartz-sericite-pyrite (QSP), propylitic and carbonate. Igneous rock textures are mainly porphyritic for sub-volcanic and granular for intrusive bodies. Phenocrysts mainly consist of plagioclase and hornblende dominated with minor of biotite and pyroxene. XRF studies and output charts show that rocks include monzonite, diorite, gabbro and gabbroic diorite. Intermediate subvolcanic units (monzonite, diorite) and mafic intrusives (gabbro and gabbroic-diorite) are related to high-potassium calc-alkaline (K2O between 2.42 to 4%) and tholeiitic (K2O between 0.15 to 0.27%) series, respectively. Subvolcanic units belong to the I-type granitoid (Chappell and White, 2001).
Mantle normalized , trace-element spider diagrams display enrichment in LREE, such as Rb, Sr, K, and Cs, and depletion in HREE, e.g., Nb, Ti, Zr that indicate magma formed in the subduction zone. Nb depletion (less than 6 ppm, between 0.5 to 5.2 ppm) in subvolcanic bodies represents a volcanic arc granitoids (VAG) tectonic setting that is related to the subduction zone (Pearce et al., 1984). Also, this reduction shows that these rocks are derived of oceanic crust (Wilson, 1989). Enrichment in LREE and depletion of HREE with a low (La/Yb)N ratio in the Hamech subvolcanic rocks (6/85 to 8/13) could represent a low degree of mantle partial melting (Wass and Rogers, 1980). Zr/Nb ratio of more than 10 for Hamech rocks (between 21 and 35 for intermediate subvolcanic and 67 to 72 for mafic bodies) indicates that parental magma has minimal crustal contamination (Karimpour et al., 2012). Sr enrichment (between 646 to 1124) and low negative Eu anomaly (Eu/Eu* ratio between 0.81 to 1/02) show that plagioclase is rare (or is not present) as residue mineral in the source and melt conditions have been in oxidation state (Tepper et al., 1993). Based on Sm/Yb vs. La/Sm (Shaw, 1970) and Ce/Yb vs. Sm/Yb (Wang et al., 2002) diagrams, parent magma is composed of 1 to 5% spinel-garnet lherzolite partial melting (with small amounts of garnet) at a depth between 65 to 67 km (upper mantle) for subvolcanic units and 5 to 20% spinel lherzolite partial melting (depletion mantle-NMORB) with a depth of less than 55 km for mafic bodies.
Suitable tectonic setting, existence of subvolcanic units with intermediate composition, magnetic activity with the nature of calc-alkaline and oxidants, data from major and REE studies, mineralization as disseminated and veinlets with high secondary iron oxides in surface show suitable conditions of porphyry and epithermal mineralization in the Hamech prospect area.

The Qarachilar Cu-Mo-Au occurrence is located in the Arasbaran ore zone (AZ), NW Iran, some 70 km north of Tabriz. The AZ is characterized by occurrence of different types of mineralization and hosts many Cu-Mo porphyry (PCD), Cu skarn, and epithermal Au deposits (Jamali et al., 2010; Jamali and Mehrabi, 2015). The main rock unit exposed in the area is Qaradagh batholith (QDB). A variety of porphyry and vein-type Cu–Mo–Au mineralization are associated with QDB. The most pronounced occurrences are in Qarachilar, Qara-Dareh, Zarli-Dareh, Aniq and Pirbolagh. This type of mineralization can be followed in other parts of northwest Iran, such as Masjed-Daghi porphyry Cu–Au deposit and Mivehrood vein-type Au mineralization in the southwest of the QDB, the Sungun PCD and the related skarn in its southeast, and Astamal Fe skarn deposit in the south of the QDB. To date, no detailed study has been undertaken to understand the characteristics of the Qarachilar occurrence and its mineralization type is controversial. The recent work by Simmonds and Moazzen (2015) also did not present relevant information for an understanding of the Qarachilar occurrence. The Re–Os age data obtained in their work were compared with similar events along the Urumieh-Dokhtar magmatic arc (UDMA) and southern Lesser Caucasus in order to elucidate the temporal pattern of mineralization across the whole QDB and the UDMA. The present paper provides an overview of the geological framework, the mineralization characteristics, and the results of geochemistry and fluid inclusion studies of the Qarachilar Cu-Mo-Au occurrence with an application to the ore genesis.

More than 37 polished thin sections from Qarachilar host rocks and mineralized and altered zones were studied by conventional petrographic and mineralogic methods at the University of Zanjan. In addition, 9 samples from non-altered and altered host rocks and mineralized veins were analyzed by ICP-MS for trace elements and REE at the Zarazma Co., Tehran, Iran. Microthermometric data were performed on primary fluid inclusions using the Linkam THMS600 heating–freezing stage at the Iranian Mineral Processing Research Center (IMPRC), Tehran, Iran.

The rock units exposed in the Qarachilar area are different sets of magmatic phases of QDB including granodiorite-quartz monzodiorite, porphyritic granite, quartz monzonite and acidic-intermediate dikes. Granodiorite-quartz monzodiorite is the dominant phase which hosts the Qarachilar quartz-sulfide veins. Mineralization at Qarachilar occurs as three quartz-sulfide veins. The veins reach up to 700-m in length and average 1-m in width, reaching a maximum of 2-m. They are generally steeply-dipping to the NE at 80°. The reported grades of Mo, Cu and Au range from 20 ppm to 3.6 wt%, 0.7 wt% to 5 wt%, and 0.23 to 37.2 g/t, respectively.
Four stages of mineralization can be distinguished at Qarachilar. Stage-1 is represented by quartz veins (ranging from centimeters up to ≤1-m width) that contain variable amounts of chalcopyrite and pyrite. Stage-2 is marked by Tm-h) and type-2 (Tm-h>Th) inclusions are homogenized in the range of 197-530°C and 203-375°C, respectively. They have a calculated bulk salinity of 29.5 to 55.1 and 32.4 to 45.6 wt% NaCl equiv., respectively. The variations in salinity and Th could be explained by a combination of mixing and boiling hydrothermal fluids. These processes led to the deposition of Cu, Mo and Au in the veins. Geology, ore mineralogy, textures, geochemistry and microthermometric data of Qarachilar occurrence are comparable with vein-type Cu-Mo-Au mineralization related to Cu-Mo porphyry and intrusion related gold deposits.

The Urmia-Naqadeh-Mahabad basin is a part of the south and west Urmia Lake drainage basin that covers some parts of East-and-West Azerbaijan and northern Kurdistan. This study is the integration of geological, hydrological, remote sensing, geochemical and airborne geophysical data classifying promising areas that are related to sandstone type uranium (U) mineralization in Iran. Based on positive factors such as favorable source, host rocks and suitable hydrological pattern, this basin is a favorable basin in Iran. According to the characteristics of lithology, tectonic, sedimentary environment, geotectonics and etc. the basin could be classified into favorable, promising and possible subbasins for mineralization of U sandstone type.
Material and Geological data show that this region is a part of the Sanandaj-Sirjan zone and consists of Precambrian metamorphic rocks which are covered by younger sedimentary and volcano-sedimentary rocks that are influenced by different metamorphic phases. More than 7597 stream sediment samples from the area have been analyzed for Se¡V¡ Mo¡ As¡Cu¡ Ag¡ Zn¡ Co¡ Ni¡ Pb¡ Ti¡ Th¡ Zr¡ P and Sn. The basin is divided into 11 individual sub-basins. Radiometric data of the basin have been acquisitioned during 1976-1978 by an Australian-German- French Company with line separation of 500 meters and 120 meters of nominal terrain clearance.
Remote sensing data reveals that the western subbasin is suitable for sandstone type uranium mineralization. Based on geochemical evidences, the Au, Zn, Sn, As and Pb elements were enriched. Geophysical investigation reveals that the Eastern basin includes high amounts of U and low amounts of Th. Hydrogeological study demonstrates that the trend of groundwater is from the west to the east.
Geochemical data revealed that we can divide the basin into 11 subbasins which are characterized as follows: 1. Ghara Aghaj (126 Km2), North to south trend is situated at the northern part of the basin. At this basin Ni, Co, Cu and V are reported but it is not related to mineralization.
2. Ghoma – Bezrgah (36 Km2). The East to the West trend is situated at the western part of the basin. At this basin Pb, As, Sn, Zn and Au are reported which can be related to skarn mineralization.
3. Piram – Shilan (342 Km2). At this basin Pb, Zn, As and Mo are reported which contain source rocks of uranium mineralization but there is no evidence of host rock and mineralization.
4. Pirestan1 (28 Km2). According to geological data a granitic body which can be the source of uranium mineralization and cretaceous volcanic rock outcropped. The fault system is weak by the north to the south trend. The anomalies of Pb, Mo, As and Sn are reported but there is no evidence of mineralization.
5. Kooh-e sabz poosh (34 Km2). Based on geological data half of the area is covered by granodioritic body which can be the source of uranium mineralization. The fault system has two trends (NE-SW and N-S). The anomalies of V, As, Mo and Co are reported but there is no evidence of mineralization.
6. Pirestan2 ((83 Km2). According to geological data a granitic and granodioritic body can be the source of uranium mineralization. The anomalies of Mo, Sn, Co, As and Zn are reported but there is no evidence of mineralization.
7. Chahar Taq (36 Km2). The fault system has the NE to SW trend and trusted mechanism. The anomalies of Zn, Ni and Au are reported but there is no evidence of mineralization.
8. Zaveh Kooh (111 Km2). The rock units have the NW to SE trend according to the Sanadaj-Sirjan trend. The anomalies of Pb, As, Sn, Mo, Ti, Cu, Ni and Au are reported but there is no evidence of uranium mineralization but there is some evidence of orogenic gold mineralization.
9. Saqqez-Baneh (465 Km2). The rock units have the NW to SE trend according to the Sanadaj-Sirjan trend. The anomalies of Co, Ti, Cu, Zn, Pb, Ni, Mo, Sn, Ag, Au and As are reported but there is no evidence of uranium mineralization and the same as the 8th subbasin there are known deposits of orogenic gold mineralization.
10. Charkeh (104 Km2). The rock units have the NW to SE trend. The anomalies of Zn, Mo, Sn, V, Ni, Au, As and Pb are reported but there is no evidence of mineralization.
11. Sheikh Ebrahim (38 Km2). The anomalies of Mo, Au, As and Pb are reported.
The integration of the different layers shows that the prospecting area is suitable for future exploration of blind deposits.
Geophysical data was processed and revealed those areas which have data. They can be classified into 5 different classes based on U and Th concentrations.
The Hydrogeological data consist of EC, pH, Eh, DO and salinity. And the temperature was measured at the field by Sension 156 multimeter and was sent for ICP-MS analysis to the AMDEL and Applied Geological Research Center (Karaj) laboratories. Two samples were obtained from each well by Widel et al.’s (1998) method. One sample was analyzed for Ca2¡ Mg2¡ Na¡ K¡ CO32-¡ HCO3-¡ SO42-and Cl- and the other samples were analyzed for major and trace elements. At each basin charge, the discharge and the trend of underground water were defined.
The results revealed that this basin contains alkaline magmatic rocks such as alkaline rhyolite and tuff which are situated in reduced shale and continental volcanic clastic rocks and can be the source of uranium at the study area. Besides these rocks, tuffaceous sandstone, metamorphose sandstone and young alluvial by the reduction condition can be the suitable hosts for mineralization.
Based on geological, geochemical, hydrogeological and geophysical data, the western basin is suitable for sandstone type uranium deposit and also there is some evidence of mineralization.

The Zendan salt dome is located at 80 Km north of Bandar-Lengeh and 110 Km west of Bandar-Khamir cities in the Hormozgan province. Based on the structural geology of Iran, the Zendan salt dome is placed in the southeastern part of the Zagros zone (Stocklin, 1968). Important units in this area are Hormuz, Mishan, Aghajari and Bakhtiari formations with the Precambrian age (Alian and Bazamad, 2014). The Hormuz formation with the four members of H1, H2, H3, and H4 is the oldest formation (Ahmadzadeh Heravi et al., 1991). Basalt and diabase rocks are mostly rocks that are exposed in the Zendan salt dome. Magnetite and hematite iron mineralization happened in all the building rocks of salt dome, and is not a uniform mineralization. Iron mineralization contains hematite, spicularite, magnetite, goethite, and iron hydroxides. Magnetite-hematite-oligist layers (red soil) are the most iron mineralization in the Zendan salt dome, which are usually broken and scattered with gypsum layers (mostly anhydrite), respectively. Another form of iron mineralization is a mixture of hematite and magnetite (about 10 to 15%) in diabase rocks. Copper mineralization consists of pyrite and chalcopyrite minerals that are mostly in tuff and shale units. The presence of low immobile trace elements in the Zendan salt dome and type of alteration shows that maybe the origin of this iron is deposited from brine fluid. Therefore, this deposit can be classified into VMS deposits.

We have taken 60 samples rocks from the Zendan salt dome, and then prepared 20 thin and polished sections. Petrographic studies were done and 9 samples were selected for analysis. These samples were sent to the Zarzma laboratory and the amount of FeO was determined by the wet chemical method and other amounts of oxides were determined by XRF. Six samples were analyzed for determining the major elements with the XRF method in the Binalood laboratory. Nine samples from vines mineralization were sent to the Zarzma laboratory and were analyzed with Inductively Coupled Plasma (ICP-OES). Two samples of igneous rocks were analyzed for determining major, minor and trace elements with ICP in Zarzma laboratory.

Magmatic and evaporate fluids are sources of hydrothermal iron mineralization (Barton and Johnson, 2004). Sodic-calcic, semi sub deep pottasic, low silicific and sericitic alterations are related to magmatic fluids (Barton and Johnson, 2004). In the Zendan salt dome it seems that plutonic rocks prepared the source of temperature and made brine liquids evaporate and then moved the metals. Sodic alteration is one of the frequency alterations in the hydrothermal iron deposits related to high brain liquids (Arencibia and Clark, 1996). Immobile elements such as Ni, P and V show a high amount of magmatic iron deposit (Nystrom and Henriquiz, 1994). There is a significant relationship between the amount of Fe and the frequency elements. With an increase in the Fe content, the amount of TiO2, K2O, SiO2 and Al2O3 oxides decrease and the amounts of Ni and Cr2O3 increase. Low immobile elements’ contents and alteration type in the Zendan salt dome show the iron mineralization effect of brines fluids. On the other hand, this deposit can be classified into VMS deposits.

Iron mineralization in Zendan salt dome is often magnetite, hematite, pyrite and chalcopyrite. Iron mineralization in the Zendan salt dome consists mostly of hematite, limonite and oligist (red soil) layers. They are usually found as scattered discontinuous layers and are alternated with gypsum layers. Hematite is the most abundant and dominant. There is a significant relationship between the amount of Fe and frequency elements. With increasing the Fe content, the amounts of TiO2, K2O, SiO2 and Al2O3 oxides decrease and the amounts of Ni and Cr2O3 increase . Low immobile element's contents and alteration type in the Zendan salt dome shows the iron mineralization effect on brines fluids. On the other hand, this deposit can be classified into the VMS deposits.
Acknowledgements: The authors would like to thank the Ashrafpour, Hagheghe and all miners.

Complete recognition of exploration criteria is considered as an important step in the systematic and scientific analysis of mineral potential mapping. The starting point of this analysis is recognition of the mineral potentials and the mechanism of their formation in different geological areas. In order to achieve such goals we can benefit from the known mineralization information. Integrating and analyzing all the data in the geographic information systems (GIS) can lead to the identification of promising mineral areas for future studies (San Soleimani et al., 2011). GIS can be used to organize, process, analyze and integrate the results of geological, geochemical and geophysical, tectonic and alteration studies in order to identify and evaluate the potential of different minerals (Bonham Carter, 1998). The aim of this paper is to apply the fuzzy integration method in GIS with using all the information, without the need to simplify them, in less time and with acceptable accuracy in order to recognize mineral potentials in the Ramand region. Investigation of mineral potentials in this area with using fuzzy logic in addition to the scientific-research aspects, can provide the discovery of appropriate patterns for other mineral resources in Iran.

The first step in any exploration project is that mapping is done with the aim of optimal potential to provide a model for the exploration of possible deposits in the region. This process in next steps will be continued with an extraction of useful information from various data that are contained in the database and this done work is done based on the properties of the elements under prospecting and the relevant exploration models. However, in the final stage, the combination of these maps is based on different models (Bonham Carter, 1998). The pre-requisite for the production of the mineral potential map, is to determine the weight and value which reflects the relative importance of the data classification (Hosseinali and Alesheikh, 2008). According to the study's default that is modeling with using fuzzy logic, a range of values between zero and one can be used to express the degree or the value of a collection (Novriadi and Darijanto, 2006) This is such that zero means lack of full membership and value of one is meant to be a full member of the collection. So, other set members can also be allocated values between zero and one and based on the degree of their membership to the set. So, it can be said that in the mining exploration, membership values are used to indicate the relative importance of each map as well as the relative importance of each class of a single map (Bonham Carter, 1998). Exploratory layers produced in GIS (in the fuzzy theory section), appear in the role of fuzzy sets and are combined by fuzzy operators (Table 1). The combining layers in the fuzzy method express the concept from the optimal options.

In this study, some of the geo-referenced data consisting of geological data, remote sensing, tectonic and geophysical data have been used. Geological data for separate lithological units in the region and the identification of faults, remote sensing data to identify hydrothermal alterations and fault lineaments and airborne geophysical data in order to detect magnetic fault lineaments and check the changes of magnetic susceptibility related to hydrothermal alterations are used so that after collecting and entering data, processing the necessary studies has been carried out on them. Finally, by combining the results of each layer and giving the fuzzy weighting to them based on their importance in mineralization and the use of the fuzzy algorithm and gamma (the fuzzy operator) in GIS, the final map is obtained to identify the potential areas with using it in the Ramand region. The possibility to acquire the exploration pattern of base and precious metals is provided in the mineral-prone areas.

In this study, there was a lot of exploration of information such that the decision to determine the potential points and continuing the exploration activities had been made very difficult. Thus, with use of the fuzzy integration method in GIS, all of the information were managed without any need to simplify them, in less time and with acceptable accuracy. Fuzzy logic is a method based on expert knowledge that is used for integration of exploration data and producing the optimal potential map of the Ramand regional reserves. It points to promising and priority areas for accurate and detailed information. Therefore, it is better to carry out exploration operations and reduces the cost and time as well as expedition to decision-making. And accuracy is very effective.

Remote sensing has shown tremendous potential in the identification of alteration zones. The importance of this science for mineral exploration and recognition of alteration zones with lower cost, time, and manpower is confirmed in many studies (Amer et al., 2012; Hosseinjani Zadeh et al., 2014; Tayebi and Tangestani, 2015; Shahriari et al., 2015). Gold is one of the byproducts in most of the porphyry copper deposits (PCDs). Although the gold assay is partly low and reaches between 0.012- 0.38 g/t in these deposits, the high tonnage of copper deposits provides a considerable source of gold which has an important economic value (Kerrich et al., 2000). Extension, intensity of alteration, assays and the type of mineralization vary in different deposits. For instance, many Au-poor porphyry copper deposits in southwest USA, Central Asia, and west of South America are associated with widespread phyllic alteration (Kesler et al., 2002). In addition, there is a positive correlation between gold and magnetite in PCDs (Kesler et al., 2002; Shafiei and Shahabpour, 2008; Sillitoe, 1979). Therefore, aeromagnetic investigation could be useful in identification of these deposits. The aim of this research is discrimination of alteration zones and investigation areas with high concentration of gold through processing of remote sensing and aeromagnetic data.
A number of prone areas with different concentrations of gold in Dehaj-Sarduiyeh copper belt including Sar Kuh, Abdar, Meiduk, Sarcheshmeh, Darrehzar, Sara, Iju and Seridune were investigated using the processing of Advanced space borne thermal emission and reflection radiometer (ASTER), and aeromagnetic data. Pre-processing acts such as crosstalk correction and Internal Average Relative Reflection (IARR) calibration were implemented on the ASTER data in order to remove noise and acquire surface reflectance. The alteration minerals were discriminated by implementation of appropriate algorithms such as color composite and partial sub-pixel method, and Mixture tuned matched filtering (MTMF) on a pre-processed and calibrated ASTER data. The results were verified by field surveys and laboratory analyses such as spectroscopic studies, optical microscopy, and XRD. The boundary of each deposit was determined by the results obtained from ASTER data. The aeromagnetic data were also processed using different filters like the reduced to the pole first and second vertical derivatives. Then the aeromagnetic data were clipped according to the boundaries determined with ASTER data and were exported into the GIS environment along with the determined abundances of altered minerals for the investigation of the characteristics of areas with a high concentration of gold.
The results of ASTER image processing revealed that the distribution of phyllic alteration is high in the area. It is shown that most of the poor-Gold porphyry copper deposits are associated with widespread phyllic (Kesler et al., 2002). Therefore, the high exposure of phyllic confirms the low amount of gold in the study area. According to aeromagnetic results, the maximum and minimum differences in magnetic intensity were observed at Abdar- Sarkuh and Iju- Seridun, respectively which have high and low concentrations of gold in these deposits. In addition, the results which were obtained from reduced to pole transform revealed most correspondence with gold differences in the deposits.
ASTER datasets were conducted on the eight porphyry copper deposits (PCDs) of Urumieh–Dokhtar magmatic belt including Sar Kuh, Abdar, Meiduk, Sarcheshmeh, Darrehzar, Sara, Iju and Seridune to investigate and detect the high potential areas for gold mineralization. ASTER false color composite image of bands 4, 6, and 8 in red green, and blue determined argillic and sericite altered rocks, as light red to pink, and propylitic altered rocks, as dark to light green. The results obtained from MTMF revealed that sericite is the dominant alteration mineral in the area. The discriminated minerals at most occurrences, including Sarcheshmeh, Meiduk, Sereidun, Darrehzar, Abdar and Iju showed a circular to elliptical pattern with sericite as dominant zone, scattered kaolinite and sparse alunite–pyrophyllite, surrounded by a combination of epidote, chlorite, and calcite. Investigation of aeromagnetic data by applying different filters showed that the magnetic intensity is high in areas with a high concentration of gold. For example, the maximum differences in magnetic intensity were observed at the Sar Kuh and Abdar which contain a higher concentration of gold.
Acknowledgements : The authors would like to acknowledge the Institute of science and high technology and environmental sciences, Graduate University of Advanced Technology, Kerman, Iran for their financial support during this study under the contract number 7.395.

The Tabriz basin is an intra-mountain basin (Reichenbacher et al., 2011), which includes the Qom Red Bed Formation along with the Miocene Upper Red Formation. The lower unit of the Upper Red formation, M2mg unit, which hosts copper deposits includes an alternation of green grey sandstone and red marl with the interlayer of gypsiferous and saltiferous sediments (Sadati et al., 2013). Based on paleontological evidence, this unit is middle Miocene in age and is overlain by red sandstone, marl, shale (M3ms, M4sm) and locally up to red conglomerate (M5sc). In addition, this unit has considerable evaporitic layers, such as gypsum and salt.
On the basis of field study all mineralization is distributed in the light-colored layers of the red sedimentary sequence, especially at the boundary between a red layer and a light-colored layer and is mostly restricted to within palaeo channels which consist of greenish-grey, well-sorted coarse- to very coarse-grained sandstones to microconglomerates.
Both pyrite and copper-bearing minerals usually occur in the stratification of the organic matter- bearing host rocks which are mainly composed of gray sandstone.
The size of organic matter varies from a few millimeters to 5-10 cm in length; almost all fragments are flattened and oriented conformably to bedding planes of host sedimentary rocks. Also,
fine-grained sulfides are disseminated along the bedding planes in the sandstone. Copper precipitation in these places was possibly promoted by reduction from such organic materials.
Sampling and analytical

Investigations on mineralized samples showed that pyrite is the first sulfide mineral precipitated in the selected samples, followed by chalcopyrite, bornite, chalcocite, digenit, and covellite. The intergrown nature of sulphur-bearing minerals, along with their small grain size and their inter locking with detrital grains and calcite cement, make physical separation extremely difficult, although microdrilling techniques can achieve spatial resolutions for these samples. In the laboratory 25 to 100 µg (weight depends on the mineral analyzed) of the samples derived from microdrilling was combusted in a Eurovector 3000 elemental analyzer, yielding sulfur dioxide that was delivered to an Isoprime mass spectrometer using continuous-flow techniques, with helium as the carrier gas.
Also, sulfide mineral powder was analyzed for the sulfur isotope compositions. Some samples were crushed to 40 to 60 meshes and the sulfide mineral separates were handpicked under a binocular microscope. The sulfur isotopes were analyzed at the Stable Isotope Laboratory, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing. The isotopic data are reported using the δ notation in units of per mil, relative to the Cañón Diablo troilite (CDT) standard.
Organic carbon (TOC) was determined by treating powdered samples with 6 M HCl to remove the carbonate. The sample was then rinsed to remove the acid. The mass difference between the original sample and the acid-treated residue was used to determine the carbonate content.
The dried sample was then combusted and the evolved CO2 was analyzed on the mass spectrometer. During the mass spectrometric analysis the sample peak height was calibrated against organic carbon standards to estimate the organic carbon content.
Result and

Framboidal pyrite is the most common typical byproduct of bacterial sulfate reduction (BSR), a process that occurs at temperatures from 0°C up to about 60–80°C (Donahue et al., 2008).
The metabolic activity of the sulfate reducing bacteria generally depletes (or fractionates) the resulting sulfide in 34S, by up to 70% (Kalender, 2011).
The availability of S content is consistent with controlling δ34Ssulfide in some portions of this study area, but not all. Total organic carbon (TOC) is above 4% for one mineralized sample of the Upper red Formation.
Sulfide sulphur and organic carbon distribution shows that pyrite-rich sandstones are the copper ore precursor, and that mineralizing the processes provoked the depletion of both reduced S and organic C as a consequence of interaction with an oxidized Cu-bearing fluid. On the other hand, lowed 34S values are consistent with bacteriogenic derivation of sulphur.

Taking into account the sedimentary environment, the abundant presence of the former evaporit layers in the host rock, the presence of evaporit layers below and above the mineralized rocks, and the absence of a widespread magmatic sulfur source, it is concluded that the Cu-Co sulfides of the Nahand-Ivand deposits obtained their sulfur by either bacterial or thermochemical reduction of sedimentary sulfate. The examined samples preserved original sedimentary textures (i.e. immature organic matter and sedimentary bedding). These geological evidences point to the fact that a biological (thermochemical) sulfate reduction is unlikely. Therefore, the sulfate-reducing bacteria were responsible for pyrite formation in the examined sample.
The S isotope composition of pyrite in this study is related to organic C abundance. Most of the samples show a correlation between S and C, but mineralized samples are relatively enriched in S and TOC content.

There is an iron mining complex called Shahrak 60 km east of the Takab town, NW Iran. The exploration in the Shahrak deposit (general name for all iron deposits of the area) started in 1992 by the Foolad Saba Noor Co. and continued in several periods until 2008. The Shahrak deposit is comprised of 10 ore deposits including Sarab-1, Sarab-2, Sarab-3, Korkora-1, Korkora-2, Shahrak-1, Shahrak-2, Shahrak-3, Cheshmeh and Golezar deposits (Sheikhi, 1995) with a total 60 million tons of proven ore reserves. The Fe grade ranges from 45 to 65% (average 50%). The ore reserves of these deposits are different. Sarab-3 ore deposit with 9 million tons of 54% Fe and 8.95% S is located at the northeast of Kurdistan and in the Sanandaj-Sirjan structural zone at the latitude of 36°20´ and longitude of 47°32´.
Sixty thin-polished, polished and thin sections are made for the study of mineralogy and petrology, and among them six thin-polished sections were selected for EPMA (Electron Probe Micro Analysis) on magnetite and hematite. EPMA was performed using the Cameca Sx100 electron microprobe at the Iran Mineral Processing Research Center (IMPRC) with wavelength-dispersive spectrometers.
Based on field observations and petrographic studies, lithologic composition of intrusion (Miocene age) ranges within the diorite-leucodiorite, monzodiorite-quartz monzodiorite, granodiorite-granite. With the intrusion of those igneous bodies into carbonate rocks of the Qom Formation, contact metamorphism was formed. The formation of Sarab-3 iron deposit occurred at the three stages of metamorphism, skarnification and supergene. Based on field geology of the deposit, it is composed of endoskarn, exoskarn including Fe ore±sulfides. At the metamorphic stage, after intrusion of intrusive bodies in carbonate rocks, recrystallization took place and marble was formed. With more crystallization of magma, evolved hydrothermal fluids intruded into host rocks. Skarnification occurred at the two stages of progressive and regressive. At the progressive stage, the reaction of fluids and host rocks turned to the formation of anhydrous calc-silicate minerals such as garnet and clinopyroxene. At the regressive stage with the change of physicochemical conditions like decreasing temperature, these minerals converted to hydrous silicates (tremolite-actinolite, epidote) and phyllosilcates (chlorite, serpentine, talk, and phlogopite). Also, minerals such as oxides (magnetite and hematite), sulfides (pyrite and chalcopyrite) and calcite were formed. At a late stage, with activations of fluids, quartz-calcite mineralized veins formed. At the supergene stage, the oxidation process leads to the formation of alteration minerals from the main mineralization. Although there are magnesian minerals in the skarn, its main composition is calcic. The shape of the deposit is lentoid to horizontal and in some places bed formed along with some alteration halos. The ore minerals include low Ti-magnetite (with an average of 0.02 wt % Ti), hematite and sulfide minerals such as pyrite, pyrrhotite and chalcopyrite. Magnetite is the most important mineral with disseminated, vein, open-space filling, aggregate, accumulation, island and cataclastic textures. The magnetite at Sarab-3 is generated in 2 stages: At the first stage, magnetite has mass to mosaic textures that indicate the first phase of deposition in the area and at the second stage magnetite is gray magnetites that are placed as narrow bands around hematite or on the primary magnetite. Hematite in the area is formed either as hypogene hematite with plate or blade texture that is formed before the formation of early magnetite or supergene hematite that itself is formed due to alteration and weathering of magnetite in the superficial and shallow part of the deposit. In the surface area of the deposit, ore minerals are strongly altered to mixtures of oxide and hydroxide minerals like hematite, limonite and goethite which changed the color of the ore body to yellow, deep orange, red and brown. Pyrites are the most important sulfide minerals in the area that are formed in five stages respectively, mass texture (Py1), Melnikovity (py2), vein-veinlet (py3), inclusion (py4), and mineralized veins (py5). Sericitization, calcitization, serpentinization, chloritization, epidotization, uralitization, argilitization, propylitization and actinolitizion are the important alterations in the area from which chloritization-epidotization and calcitization in the ore and propylitic and argilitization alteration in the plutonic rocks are dominant. The EPMA analytical results on 23 points on magnetite and hematite mineral suggest that the amounts of TiO2 and V2O5 (0.03 wt % and 0.01 wt % in average, respectively) are low in contrast to MnO and Al2O3 (0.09 wt % and 1.59 wt % on the average, respectively). Therefore, it fits in the skarn ore deposit domain on Ni/(Cr) versus Ti and Caɟ versus Ti discrimination diagrams of iron ore deposits (Dupuis and Beaudoin, 2011). High Mn in the rock samples of Sarab-3 may have resulted from the substitution of Fe by Mn in magnetite and hematite structure that can be a sign of hydrothermal skarn. Manganes, Al, Cu, Mg, and Ca show a negative correlation with Fe that may have resulted from the concentration and the substitution of these elements in tremolite-actinolite, epidote, chlorite, calcite, phlogopite and chalcopyrite. According to the chemistry of magnetite and plotting them on V2O5 versus TiO2 and V2O5 versus Cr2O3 diagrams, it can be recognized that the samples of the Sarab-3 deposit resemble to exoskarn magnetite of Goto and endoskarn Karakaen deposit of Senegal. Mineralographical and geochemical evidence from ore, the occurrence of iron in contact with the carbonates and calc silicates such as garnet, pyroxene, secondary calcite, epidote and chlorite suggest iron skarn genesis for the Sarab-3 deposit.