افشین اکبرپور

Saveh-Razan copper (± gold) area, with WNW direction in the northwest of Urmia-Dokhtar magmatic belt, with the highest reaction to right-sided shear zones and structural trend change during the Oligomyocene, leads to the placement of semi-deep Oligomyocene diorite massifs in shallow rock depths. It is an Eocene volcano. By creating different types of mass-related hydrothermal alteration (propylitic, intermediate-advanced argillaceous, and phyllite) along the fractures, the system concentrates the mineralizations in quartz-sulfide veins, hydrothermal incisions, and concentrated sulfide-bearing filaments. Common features of metallurgy in this area are fluid homogenization temperature between 250 to 350 ° C and salinity range of 6-28% by weight of salt, containing CO2 gas and liquid phase of liquid and the presence of sulfides such as pyrite, chalcopyrite, burnite, chalcocite and sulfosalts in related reserves. There is also more gold than silver. Therefore, these features are most similar to the mass-related intermediate-type epitermal deposits that form in calcoalkalkene magmatic arcs.

The Gheshlaghe mil deposit is located in the Urumieh-Dokhtar magmatic belt. Vein- type mineralization is concordance within the rhyodacitic and rhyolite meta-tuff with Eocene age. Alteration zones of sericite, silica, argillic and iron oxides are observed in the investigated area. Primary sulfide minerals of pyrite, fine-grained chalcopyrite and Oxidized specularite and Secondary minerals goethite, limonite, malachite and quartz in Microscopic and field studies have been identified. Based on X-ray diffraction analysis studies minerals such as chlorite, illite, kaolinite, hematite, quartz, mica group and calcite have been observed in the bearing gold veins. According litho-geochemical studies, the gold element has a positive correlation with iron, molybdenum, nickel and lead. A number of 157 fluid inclusion studies in the Gheshlaghe Mil ore mineralization area has been showed mineralization temperature of 99 to 299 °C, rate of salinity ore deposit 1.81 and 12.30 equivalent to the Nacl weight percent. Using Raman laser studies (13 points), the presence of gaseous phases (CO2, N2, H2O) in the fluid inclusions have been demonstrated. Regarding to studies have been done in this area, the Gheshlaghe Mil ore mineralization can to know to a vein type- hydrothermal bearing gold-copper ore deposit.

Anomaly XVI-B located in Central Iran Structural Zone. The oldest rock formations in this study area are related to metamorphic rocks which are included gneiss, micaschist, amphibolite and megmatite. Mineralized intruded mass distinguished by alkaline diorite-syenite that cut Bonoshorow metamorphic complex and limestone units. Metallic mineralization is occurred in syenite, gabbro and skarn rocks. Magnetite is the most abundant mineral in anomaly XVI-B and also it has been seen as stripe, mass, disseminated and filling empty space textures. The magnetite grains are shaped to shapeless. Magnetite is oxidized near the surface and converts to hematite, goethite and other iron oxides. Another metallic mineral which are associated with magnetite are pyrite, and chalcopyrite, which have been found in quartz, actinolite, calcite, and epidotite that come with various forms within host rocks, syenite, gabbro, and skarn. According to the graphs of rare earth elements in iron mineralization and intruded units indicates the possible similarity of the source of iron mineralization with intruded mass. The grade of iron oxide in ore deposit varies between 25 and 75 percent. The iron element has a negative correlation with oxide of titanium oxides, magnesium, manganese, phosphorus, potassium and sodium. Based on cobalt relationship with nickel, chromium - nickel, and chromium - vanadium, so anomaly XVI-B iron deposit is related to the hydrothermal deposits. Due to the ratio of Al / Co and Sn / Ga, anomaly XVI-B is recognized as a skarn type deposit. Based on the scattering patterns of the rare elements, anomaly XVI-B is more similar to the skarn type deposit. Geological and mineralogical evidence, as well as the geochemical properties of the magnetite, indicate that skarn deposit is source of iron mineralization. Iron is transported by the hot fluids that come from intruded units that accumulates between boundary of metamorphic and marble units. δ34S value is between 21.24% - 22.27%. The source of Sulphur isotope is meteoric and ancient marine water. As a result, the accompaniment of magnetite with pyrite can be found that the source of magnetite is identical with pyrite.

The Ebrahim-Abad iron deposit, consisting of Paleozoic metamorphic rocks, Mesozoic plutonic bodies and metasomatic rocks, occurred in the northwest of Divandere and the Sanandaj- Sirjan structural zone.The metamorphic rocks including micaschist and marble are cut by plutonic intrusive rocks (granodiorite to milonitic and cataclastic granite). Mica schist and associated detrital sediments have been changed in the low- grade greenschist facies. Marbles and plutonic rocks have also undergone cataclastic metamorphism along shear zones. Metasomatic rocks are garnet- amphibolite to garnititic skarn composition crosscutting by magnetic veins. Iron mineralization as magnetite, chiefly occurred as lenses, veins and veinlets as well as dissimented grains. Massive, dissiminated, replacement, and network textures are the main textures of this deposit. Magnetite developed as amorphous, fine (less than 1 mm), or dissiminated. Chlorite, trermolite- actinolite, epidote, garnet, and quartz with minor clay minerals and calcite are the gangue minerals of the studied ore deposit. Iron oxide grade varies from 14 to 47 FeO%. Fe shows a negative correlation with S, and Si, Al, Mg, Mn, Ca, K oxides but positive correlation with Cr and Co. Ti/Ni+Cr and Ni/Cr diagrams point to the hydrothermal origin of the iron ore under study. The variations in the cobalt, nickel, vanadium, and titanium contents indicate that the skarn- hydrothermal origin of the Ebrahim- Abad iron deposit. It seems that the iron oxide remobilized by hot hydrothermal fluids originated from intrusive bodies and redeposited in marble, mica schist, greenschist, and skarn.

Yapal iron ore body is located in northwest of Sanandaj-Sirjan zone. A complex of Paleozoic metamorphed rocks including green schist, mica schist, chlorite schist with green schist facies degree, plus skarn and marble outcrop in this area.. Iron mineralization generally occurs as magnetite with the shapes of lentoid, veins, veinlets and dots in garnet schist and greenschist and near marble outcrop in area. Ore textures are observed as dispersed, stock, replacement and network like. The iron oxide grade varies between 30 to 60 percent. Iron element negatively correlates with sulfur and positively correlates with titanium, magnesium, manganese and the other main oxides. Based on the relation between cobalt and nickel, this ore body is located within hydrothermal-originated category. Some samples are located in the hydrothermal-volcanogenic boundary. Based on distribution patterns of rare earth elements, Yapal iron ore has more similarities with skarn type mineralizations. Geochemical evidences of magnetite and the variations of cobalt, nickel, silica and aluminum suggest the skarn origin for Yapal iron ore. That means the iron has been mobilized by the hot fluids originated by intrusive stocks and precipitated in contact of metamorphic and marble units.

The Darreh Rahim Iron deposit occurred in 2km northwest of Ghohroud village, 25 km south of Kashan city, in Ghamsar county suburb, Isfahan province, on Urumyeh-Dokhtar magmatic belt. . Based on the petrography data, the main intrusive body of the district has medium to coarse granular texture and granodiorite rock composition. Injection of this intrusive body in the Cretaceous age limestone caused the formation of skarn processes and related Iron mineralization. An assemblage of pyroxene, chlorite, garnet, calcite and quartz are the main components of skarn and also gang minerals of the ore. Also all evidences of mineralogy, structure and texture, geochemistry and tectonic setting and Ni/(Cr+Mn)toTi+V andCa+Al+Mn toTi+V diagrams showed a similarity of the DarrehRhim ore deposit to Iron-Copper mineralization.

IntroductionThe Qahr-abad fluorite deposit is located in the area of 36°10′ 3′′ N and 46°34′ 21′′E within the Sanandaj-Sirjan district east of the Kurdistan province , Iran and it is located ~57 km southeast of the city of Saqqez (Kholghi Khasraghi, 1999). This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks of Elika formation and controlled by the regional NW–SE trending Zagross thrust nappe system. Fault trends in this area are perpendicular to fault trends in the Zagros zone. The fault dips are nearly vertical and mineralization has occurred in the brecciation fault zone (Talaii, 2010). The rough geological instruction of the deposit has indicated that it is similar to worldwide Epithermal deposits.
The mineralization occurs as replacement (type I)/ open-space (type II) vein fillings and bodies within Mesozoic lime stones (mostly Upper Triassic and Lower Jurassic members of the Elika Formation), where they crop out to form horst structures. The mineralization is typically associated with post Pliocene disjunctive faults, which in part appear to have served as channel ways for the fluorite forming fluids that are representative of the geological setting of the mineralized area.
Fluorite occurs in several color variations such as green, violet, blue, white or colorless, and is accompanied by quartz, barite and calcite (Moslehi, 2013).
Materials and methodsThe minerals sampled for the fluid inclusion study include fluorite from mineralization stages. Samples covered all ore types. Micro thermometry analyses for 23 samples were performed after careful microscopic observation of 35 sections and 30 doubly polished sections. Micro thermometry was undertaken using a Linkam THS600 heating-freezing stage, with a measurable temperature range of between −196 and  °C (precision of freezing data and homogenization temperature of ±0.2 °C). Micro thermometry was undertaken in the Department of geology of the Karazmy University.
ResultsPetrography and classification of inclusions:The samples used for the inclusion study were doubly polished sections of fluorite from mineralization stages 1 to 2. A number of inclusion types were identified. These include negative crystals and elongate round, polygonal or irregular shapes with a size range from

The Chahmora copper deposit is located at South west of Shahrud, within the Torud-Chahshirin magmatic arc. Mineralization in the Chahmora area occurred within volcanic units of Eocene. Based on field and laboratory investigations, the outcropped rocks in the Chahmora deposit are andesite, andesite – basalt, trachy andesite, trachy andesite basalt and several small exposures of pyroclastic rocks such as agglomerate.­ Basic to intermediate sub-volcanic bodies intruded Eocene volcanic-pyroclastic sequences. The rocks are high-K, calc-alkaline to shoshonitic in nature, and are formed at a magmatic arc setting in a subduction zone. The host rocks have been affected by silicification, carbonatization, sericitization and chloritization. The textures and structures of mineralization are vein-veinlet, replacement and open space filling. According to the mineralography studies, main minerals of copper are chalcocite, chalcopyrite, covellite, digenite, cuprite, malachite and rare native copper together with hematite. Chalcocite and malachite are the most abundant minerals. Geochemical studies indicate that copper has only relative correlation with silver (R=0.894) and arsenic (R=0.520).Since silver has not founded as an independent crystalline phase, therefore copper was replaced by silver in chalcocite. . Fluid inclusion studies on trapped fluids in quartz and calcite show average homogenization temperature of 200-220ºC and fluids salinity degree of 0/97-1/37 and 3/67-4/07 %wt NaCl. Copper mineralization in the Chahmora deposit has similarities in mineralogy, host rock, texture, structure and geometry with manto-type and volcanic red bed copper deposits.

The Qahr-abad fluorite deposit is located ~58 km southeast of Saqqez city, Kurdistan province. This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks. Violet, green and colorless fluorites are recognized. Quartz, dolomite, calcite and barite are gangues. REE geochemistry of the depositshows that the REE content of the fluorites lies between 20.18 and 48.38 ppm. The relatively higher concentration of LREEs in violet and colorless fluorites suggests that they formed at the first stages of mineralization. Calculation of Eu anomalies indicates that the fluorites formed in an alkaline to neutral and to some extent oxidizing conditions because the Eu anomaly cover a narrow range around 1. Negative Ceanomaly also confirms the oxidizing conditions for mineralizing fluids. Finally, by the studies of REE geochemistry it can be concluded that the Qahr-Abad fluorite deposit is a product of hydrothermal activity of epithermal type and the mineralizing fluids were of magmatic or a basin fossil fluids origin.Magmatic activities in this district, can explain the hydrothermal nature for the deposit.

BLEGmethod is one ofmodern methodsusedfor goldgeochemicalexplorationstudies.Themethod has helped to locate many low grade gold deposits. The significant change of the method compared to common geochemical exploration methods is to use of large volumes ofsamples regardless of their sizeandlow densityof sampling.In order to evaluate the efficiency of the BLEG geochemical method with stream sediment method, 1:100000 SiahRud sheet was chosen in geological region of Azarbaijan in a district that geological map and geochemical exploration has already been carried out.The study area is 1850 km2, located in a mountainous area of northwest Iran in the Eastern-Azarbaijan province (NW of Ahar city).The rock units of the area consist mainly of the Upper Cretaceous limestone and flysch complex, Oligocene intrusive bodies and Eocene volcanic-sedimentary rocks. The Oligocene intrusive bodies are the most important igneous unit in the area.In this project, 168 BLEG samples and 103 stream sediment samples (silt samples) were prepared and studied. The range gold values in BLEG samples are from 0.1 to20 ppb, and in the stream sediment samples from 3 to459 ppb.The results ofsampling and analysis present four districts with high anomalous degrees: 1) Anigh-GharehChilar district, 2) Namnegh district, 3) Eshtobin district, and 4) Andrian or MiveRud district. Analysis ofthe stream sedimentsamplesrepresentshigh value of Cu andAu. Correlation of the elements in stream sediments taken from the Anigh-GharehChilar district represents high correlation of gold with arsenic, copper and leads elements. Copper also shows a high correlation with molybdenum, which is in accordance with mineralization of this area.

Mineral exploration is a complex task that often requires the use of satellite imagery, geochemical and geophysical data in order to achieve a better result. The following study is a result of a research about Artificial Neural Network (Back propagation) in GIS environment to determine areas of Cr anomalies in Baneh (Kurdistan). Images of Landsat TM (the date 11/2002) has been used to determine rock alterations in the region. For determination of rock alterations and pyrite oxidation, we used band ratios 1 +2 +3 / 4 +3 and 2-3 +1 / 8 +4. Also field observations and petrography of thin section were used to control the results. GIS data and the results of the geochemical analysis were used in neural network data processing. Four types of neurons were used in the first layer. Also, 50 neurons in the second layer and 1 neuron in output layer were used. By using of the network, Cr potential maps with high accuracy of 86% were estimated (compared to ground data). This method is based on the numerical data and compared to conventional techniques (knowledge base) which has more advantages. The results showed that the use of satellite imagery and neural cells may play a significant role in geochemical mapping of mineral potential.

The aims of present study are investigation of endemic plants in Masjed-Daghi area introducing hyperaccumulator and indicator plants for gold and copper, and also describe the biogeochemical response pattern over a known mineralized site, namely the “Au- Cu” mineralization at Masjed-Daghi area. Masjed_Daghi is located in Jolfa sheet and it is underlain by Eocene flysch, andesite, trachyandesite, dacite, rhyodacite, Oligocene agglomerate and Quaternary deposits. Pervious researches reported copper porphyry mineralization in this area.Considering variety of vegetation in Jolfa and Masjed_Daghi, indicator plants for Cu, Pb and Zn mineralization in the study area were investigated. Mean metal contents (ppm) and mean biological absorption coefficients for Stachys inflata are: Cd 0.13- 1.18, Cu 14.8- 1.10, Pb 5.67- 0.52, Re 0.033- 4.4 and Zn 57.4- 2.50; for Artemisia sp.: Cd 0.373-1.40, Cu 22.06- 0.19, Pb 5.801- 0.12, Re 0.197- 97 and Zn 35.51- 0.48; for Moltkia coerulea: Cd 0.15- 5, Cu 24.6- 0.78, Pb 0.48- 0.06, Re 0.348- 116 and Zn 125.5- 9.65; for Astragalus sp.: Cd 0.033- 0.37, Cu 11.44- 0.21, Pb 0.513- 0.04, Re 0.089- 53 and Zn 21.8- 0.83; for Salvia sp.: Cd 0.047- 0.55, Cu 11.04- 0.46, Pb 2.6 0.19, Re 0.091- 19 and Zn 70.43- 3.42. This study presents that plants with high metal intake enabled us to obtain invaluable information about natural concentrations of chemical elements in the substrate, and to recognize new potential areas for mineral prospecting. In this study most of these plants have mean biological absorption coefficients exceeding or near to hyperaccumulating criterion >1 for most of the elements investigated. Most of the hyperaccumulator values belong to Stachys inflata and the indicating values belong to Stachys inflata, Artemisia sp., and Salvia sp.

Volcanic rocks with mainly andesite composition and lenzoid form outcropped in the Eocene sedimentary host rocks in the east of Sanandaj. Field studies confirm that they are intercalation with the sedimentary host rocks. In thin section, those have porphyritic, glomoroporphyric microlithic and microlithic porphyric textures. Some texture evidences such as glassy inclusion in the center of plagioclase phenocrysts, displacement of plagioclase and mafic phenocrysts with mafic hydrate minerals imply amalgamation of volcanic activity with soft sediments in shallow water; also cracking of plagioclase phenocrysts confirms this subject. Geochemical study shows that these rocks are enriched in incompatible elements such as U, Th, Pb and depleted in Nb, and Ti elements compared with chondrites, primitive mantle and NMORB. If crustal contamination can be responsible for these changes, but as usual these anomalies imply the primary magma generated above the subduction zone. This volcanic rock may have a unique origin the same as Urumieh-Dokhtar volcanic belt.

The masjeddaghi area with 8.5 km2 extent is located in 35 km for east of jolfa.The geological exploration started in this area in 2003 and soil sample method was chosen due to the geological situation topography and weathering, The sampling network was 100m*100m and 100m*200m and all samples were analyzed for 13 elements. including Au,Cr,Co,Ba,Cu,Pb,Zn,Ag, Be, Mo,Sn,Mn.The geological studies shows that the oldest rock unit outcropped is Eocene flysh widely distributed in southern and north eastern part of the area. Another outcrops are mainly volcanic, subvolcanic complex of andesite and trachyandesite, quartz monzonite and agglomerate(oligomiocene). In this area brecciated veins of barite - silicious and Cu,Pb,Zn sulfids and various pyrite type of mineralization have been identified. data processing have been carried out for analytical results(comparing main and duplicated samples data),and indicate normal distribution for Ni,Be, Mn log distribution for other elements.That these two analysis method s,factor analysis and correlation matrix analysis (using standardizing the datas (x-x/s))have been consictent. Regarding The composite haloes,the result of studies indicate Au,Ag,Be anomalies in eastern part of the area and Cu,Mo anomalies in western part of ARPACHAI valley. considering the lithology and its relation to geochemical anomalies of the area, probable presence of porphyric Cu mineralization in eastern part and epithermal high sulfide Au mineralization in quartz-barite veins are identifid,

The Masjeddaghi area is a part of Alborz-Azarbaijan Zone and located in the Jolfa 1:100000 geological map sheet. The oldest rock units cropped out widely in the south and northeast of the area belong to the Eocene flysch-type sediments. The other outcrops consist mainly of volcanic rock complex of andesites and trachyandesites affected by quartz monzonite intrusion and caused alteration of phyllic and carbonate phyllic type. The mineralization in volcanic complex is also accompanied by quartz and barite veins. The study of alterated zone around veins shows sericite, silicified, prophillitic, chloritic and alunite (jarosite) alterations. Investigation of alteration zones around mineralized veins shows epithermal gold ore in which alunitic alteration (jarocite) is the most important characteristics. The result of the study on alteration and extension of altered zones in the whole study area give rise to the probability of porphyry type copper deposit (potassic, phyllic, argillic and prophylitic alteration zone).

The Masjeddaghi area, located in the Jolfa 1/100000 geological map sheet, is a part of West Alborz zone - Azarbaijan. The oldest rock unit outcropped belongs to the Eocene flysh, widely distributed in the southern and north eastern part of the area. The other outcrops are mainly volcanic rock complex of andesite and trachyandesite affected by quartz monzonite intrusives and produced phyllic and carbonate phyllic alteration. The mineralization in volcanic complex is mainly silicic and barite veins. SEM and mineralography studies indicate the occurrence of sulphide mineralization especially Cu, Pb, and Zn sulphides. In addition, various pyrites occur as primary and secondary minerals. The galena and sphalerite mineralization can be observed in the main vein but not in the altrated area. SEM study indicates absence of gold in sulphide minerals. On the other hand fluid inclusion studies shows low temperature gold formation (120 - 150 °C) and very low salinity which specify probably that the gold is not carried along with chloridric complex in this stage. Evidences like parageneses, elements, gangue and alteration around silicified veins all indicate the presence of a polymetal gold - copper vein ore deposit of epithermal origin with high sulphide values.