---

Geological and geochcmical studies in Sinar area,
located in the north east of Khonlsan pruvince, indicate the
presence of antimony in a vast area. This cleme nt mainly
occurs as st ihni te , associated wi th na tive antimony,
kerlncsite, getchellite ('!), pyrite, chalw pyrite. arseno pyrite,
tctrahcdrite .md ga lena, in carbonate rock.'i, as veins.
veinlcts and disseminations. The gangue minerals arc
calcilc,doiomitc, barite and qua rtt. Inves tiga tions ind ica te
that thrust fllulis and brecciated zones arc the most
important channclways for migration or arc tluids, and
deposi tion of the a re assemblage and The mineralization
has occurred in seve ral physico. chcmic The strategic importance of antimony, and its
association with valu mercury and arsen ic, demand more detail inves tigat io ns in
this region.

---

The north - cast Arsanjan ophiolite complex is
part of the Neyriz ophiolite complex located 24 km north -
east of Arsanjan in the south - eastern part of the Zagros
range . In I :250,000 geologic map of Shiraz, this complex
has been conside red as an ultramalic t:umplcx, however, it is
principally represented by serpentinized harzburgite and
dunile, basalt, metadolerite, spilite, limestone, radiolarian
chert, dolos tone, sedimentary breccia, and listvenites which
arc reported fo r the first time from the outer Zagros
ophiolite belt in this article.
Economic mineral indications In this region can be
divided into two groups : 1) primary magmatic deposits
which include chromite and platinum group elements, and
2) secondary depo.c;its which are produced due to alteration,
and include listvenites and talc

---

For evaluation of the mineral potential of Sirutr area
in the north east of Khorasan, 140 stream sediment samples were
analyzed for Ni , Co, Ag, Sb, Hg and Au. Results of these
analyses ind ica te an unusual assay for most of these elemen ts,
especia lly for gold a nd ant imony. Statis tical analyses and
co mparison of geologic map with the surrace anomaly maps
indicate a posit ive re lations hip between Ni a nd Co with mafic
and ultramafic rocks in the area; while the unusual distribution
of gold, antimony and to a lesser extent mercury can be related
to the hydrotbermal processes. From this study it is concluded
th a t the statistical analyses along with the geological and
geochemical studies are very useful in recognition of the
mineralized areas and understanding of tbe mineralizing
processes.

---

Based on this study, the avcfiige gold and silver graJcs in the
SaT Chesbmeh porphyry copper deposil arc 0.06 and 1.22 gil
re.'ipcct ivcly which arc very different from the o nes repon ed previously.
In the bioti lic andes ite and a!ICrcd phyllic/potassic samples from the
siock, the high positin: correlation between the hypogene copper and
gold grades ( r=0.81 ), and gold 'lIld silw.f grades (1"=0.6 1), and gold and
si lver with the hypogene copper grade (r;:::U.72), indicatc:( I) the
contemporaneous deposition of C(lpper, gold ami silver, probably prescnt in the form of exsolution, invisihle solid solution and
nalive or elect rum within the chalcopyri te gwins.
Within the secondary sulfide enrichment zone, the gold grade is two
times more than the hypogene grade, Silver also indicates the highest
concentration within the lellched/oxidc and secondary sulfide
enrichment w nes.
This st udy indicm(:s th ~l t the Sar Chcshmeh deposit is a gold and
silver poor porphyry COPP!;;I - molybdenum deposit.

---

Gold - Polymetal mineralization of Kohe-zar area is
located alout 35 kilometers southwest of Torbat - Heydarieh
in Khorasan province. Mineralization was oeeured in quartz -
speeularite ± pyrite ± chacopyrite veins and vein lets. The main
ore minerals are specularite, chalcopyrite, pyrite, avinite (Bi -
bearing tetraedrite), acanthite, native bismuth (occurred
intergrowth with barite), native gold, electrum, coveline -
digenite and weathered minerals such as geothite,
hydrogeothite, eu-fe oxides, malachite. Ore minetalization of
Kohe - zar is related to low - sulfide, quartz - hematite type of
hydrothemal ore deposists.
On the basis of therrnobarogeochemical investigation on
quartz, medium temperature fluid with low potential
mineralization is responsible for mineralization in this area.

---

Exposed rocks at Hired gold-tin prospecting area are mainly Mesozoic and Paleocene sedimentary and Eocene volcanic rocks. Oligo-Miocene Granitoids are intruded the Eocene and older rocks. Based on petrology and physical characteristics of rocks, granitoids are two types: 1) S-type and 2) I-type. Mineralization is seen as stockwork, fault mineralized zone, skarn and in replacement. Stockwork mineralization is exposed in the eastern part of target (1) and it is found within S-type granite and silicified – tourmaline rich shale. Hypogene minerals are: pyrite, arsenopyrite, pyrrhotite, chalcopyrite, ± galena, ± sphalerite, tourmaline, quartz, chlorite, calcite and sericite. Gold is mainly found in veinlets contain sulfide, quartz and tourmaline. Based on S-type granite, stockwork mineralization, tourmaline alteration and Sn anomalies (581 ppm), Hired is a Tin – Gold mineralized system. Geochemical data from drill holes in target (1) and (3) indicate that the high value of Au, Ag, Cu, Zn, Pb, As and Sb are found mainly between depth of 50 to 100m in eastern part of target (1), therefore this area is close to the source of fluid. Tin – Gold mineralized system at Hired is associated with S-type granite.

---

Detailed studies are done in order to investigate the ore body in Sangan mine. Analyses results showed very low amount of gold in mineralized zone, (max 32 ppb). It is indicated that there is a positive relation between Au, S and As whereas there was no special relation between Au and Cu. Therefore Au can not be found along with Cu sulfides such as chalcopyrite. The LREE elements are higher than HREE in the ore body. Pyrrhotite has two generations which are distinguishable under the microscope: It might be formed either with or after magnetite formation. Careful XRD studies indicate that these two generations have different amounts of Fe and S.

---

Kuh – e- Zar gold deposit located in central part of Khaf – Bardaskan volcano-platonic belt and about 40 km west of Torbat-e-Heydariyeh area in Khorassan-e-Razavi province. The extensive exploration of the last decade done in the above belt has been caused the exploration of several Iron oxide copper – gold deposits, such as Kuh-e-Zar deposit. Several types of Tuff and Acide to intermediate lavas (lover tertiary) are widespread all over in the area. Mineralization appeared in different type such as vein, stockwork and Hydrothermal breccia in strike sleep fault zone which are hidden inside volcano plutonic rocks.The average gold grade is between 3.02 ppm and ore reserve is estimated more than 3 million tons (cut off grade = 0.7 ppm). The copper grade in mineralized zone located in intrusive bodies between 0.3 to 1.1 %. The main mineralized zones are Quartz and specularite (more than 30%). However, the various types of sulfides are very rare on surface. Pure gold can be observed together with Quartz and Specularits. Based on consideration of oxygen stable isotope () in Quartz and siderite as well as sulfur () in chalcopyrite, geochemical investigation and micro thermometric study has caused the gold mineralization through magmatic fluid with low sulfide content and high oxidation state. It is clear that the kuh-e-zar mineralization in case of paragenesis, alteration and dimension has been the only case all over the world. Regarding the lack of recognized and similar sample in the world, this deposit is a new and different variety of Iron Oxide Cu-Au (IOCG) deposit. It is introduced and named as Iron Oxide Gold deposit (IOG) or Specularite rich Gold deposits. This deposit has unusual richness in gold and LREE and is poor in copper.

---

Barika gold mineralization occurred in a Cretaceous metavolcano-sedimentary sequence at northwestern Sanandaj-Sirjan zone. Gold-rich volcanogenic massive sulfide mineralization occurred in a rhyolite to rhyolitic tuff unit which is completely in Barika shear zone. Based on electron microprobe studies, gold is observed to form electrum mostly, and in lattice of other minerals, such as pyrite, galena, tetrahedrite- tenantite, bournonite- boulangerite, twinte- vinnite. The main effect of deformation on the gold mineralization is migration of submicroscopic gold to cracks and crystal defects in minerals to form electrum under low to moderate strain and release of electrum from fractured mineral under higher strain. This behavior of gold can increase recovery of gold in Au-bearing ore deposits (Huston et al., 1992).    

---

The Muteh gold district is located about 70 km northeast of Golpaygan within Sanandaj-Sirjan metamorphic zone of Zagros Structural Belt. Geological studies show that the area had been under poly - phase metamorphism. Gold mineralization occurs in metamorphic complex which consists mainly of green schists, meta-volcanics, and gneisses. Shear zones are the host of gold mineralization, and intense alterations occur along the normal faults. Gold paragenesis minerals include pyrite, chalcopyrite, pyrrhotite and secondary minerals. There is three generation of pyrites. This contribution is aimed to improve our knowledge of understanding the source of the ore-bearing fluids in this area. In this regard, fifteen samples were selected for hydrogen, oxygen and sulfur isotope studies. The mean values of 12.4‰ and -42‰ for δ¹⁸O, and δD isotopes with the mean value of 7.75‰ of calculated fractionation factors for δ¹⁸O_H2O from quartz veins indicate that metamorphic host rocks are the most important source for the fluids and gold mineralization in the Muteh area. Gold mineralization is closely associated with intense hydrothermal alteration along the ductile shear zones. However, our observation shows that the characteristics of the gold mineralization in the study area are also similar to that of other hydrothermal with magmatic origin. Five available sulfur isotope (δ³⁴S) data are highly variable (+2.2, 6.6, 9.1, 13.9, and 16.9‰) even from the same type of hosted rocks. The isotope data, suggest that the source of sulphurs were not homogenous. Based on sulfur isotope compositions at Muteh gold district, it can be concluded that several different sources or processes could account for the sulphide fluids. The δ³⁴S values in the studied area demonstrate that source of sulphides are mainly derived from the metamorphism fluids though   hydrothermal fluids related to magmatic activities.

---

The variety of lithologies from Late Precambrian to Quaternary and suitable conditions for mineralization caused formation of Zarshuran gold and arsenic deposit in black schists, shale, limestone and dolomite. The ore paragenesis include As, Sb, Fe, Pb, Zn, Hg sulfides and gold along with fluorite, barite and quartz. The most important alteration is silicification which is more obvious in the ore zone and formed jasperoid. The gold in this deposit is found as very fine grains and is rarely visible. The rare Getchellite occurred in arsenic ore zone of Zarshuran as a red mineral with (001) cleavage. Paragenetically, this mineral is intermediate between As and Sb sulfides. Getchellite found in some epithermal gold deposits, can be used as a gold tracer.

---

MA-II area is one of the most important parts of Cu-Au porphyry mineralization at Maherabad prospect area. Subvolcanic intermediate intrusive rocks (Upper Eocene), monzonite to diorite in compositions, intruded telescopically and are mostly altered. Monzonitic porphyries had major role in mineralization. These intrusive rocks are highly altered, have dense stockwork veinlets, and show highest geochemical anomalies. Hydrothermal alteration zones are: Quartz-sericite-pyrite, silicified-propylitic, propylitic, carbonate and silicified zone. Mineralization occurs as stockwork, disseminated, and hydrothermal breccia. Stockwork is the most important type of mineralization. Veinlets found within quartz-sericite-pyrite zone are: quartz, quartz-pyrite, quartz-pyrite-chalcopyrite and pyrite-chalcopyrite ± quartz.  Veinlets within silicified-propylitic are: quartz-pyrite ± chalcopyrite, quartz-pyrite ± magnetite, quartz-pyrite-chlorite and quartz-magnetite. The density of quartz-sulfide veinlets is about 30 per m² (in center of MA-II in quartz-sericite-pyrite alteration zone). Most of sulfide minerals were oxidized. Secondary Fe-oxides are seen up to 15% in some places. Compositional variations of elements within MA-II area are as follow: Cu = 22-1073 (ppm), Au =16-886 (ppb), Mo = 5-54 (ppm), Zn = 40-754 (ppm), Pb = 14- 148 (ppm), As = 8-128 (ppm), Sb = 0.1-9 (ppm). High concentration of Cu and Au associated with high density of veinlets in quartz-sericite-pyrite zone in the center of MA-II area. There is positive correlation is between Cu and Au anomalies and veinlet density. Based on the obtained data, MA-II area is a part of porphyry Cu-Au deposit.

---

Tarikdarreh prospect area is situated in northeastern Iran at the boundary between Central Iran and Kopet-Dagh structural zones. Torbat-e-Jam granitoid intrusion of Triassic age is the main magmatic display in the district. These plutonic rocks with NW-SE trending intruded Miankouhi Formation (Upper Triassic) consisting of coaly shale, siltstone and sandstone converting those to hornfels for tens of meters around the plutons. Heavy mineral studies resulted in detecting minerals such as gold, scheelite, arsenopyrite, malachite, barite, jarosite, hematite, magnetite, specularite, galena, pyrite and garnet. Stream sediment analysis have shown anomalies of As, Cu, Bi, Co, W, Fe and Ti and a positive relationship between gold and As, Bi and Cu. Further exploration based on systematic sampling of soils around the plutonic rocks through determining statistical parameters for distribution of elements and fitting variogram of logarithmic data, has determined the anomaly threshold and quantified possible and probable anomalies. According to multi-variable statistics and factor analysis, the As, Cu, Au, Co, Fe, Mn and Ti, (W, Sb) package has a meaningful relationship with gold mineralization. The accomplished studies, as well as findings from heavy mineral, stream sediment and soil sampling show an interesting display of As, Au and to some extent Cu anomalies. Secondary dispersion halo maps for gold and its pathfinder elements such as As, Cu and Bi as well as factor analysis and additive index imply a high potential for gold in the Tarikdarreh prospect area.

---

Khunik area is located in eastern Iran, about 106 km south of Birjand. Preliminary prospecting in the area, using ASTER mineral mapping (SAM) for locating possible alteration zone in the area provided satisfactory results when checked with field observation. The area comprises outcrops of Paleocene to Eocene volcanics, which was intruded telescopically by several subvolcanic intermediate bodies. Alteration is related to some of these units. The main alteration types are propylitic, argillic and sericitic. Mineralization observed at the surface as disseminated and hydrothermal breccia. Maximum amount for distribution of gold, silver and arsenic are in places within stream sediments where upstreams alteration zone of  propylitic, argillic-silicified and hydrothermal breccia are located. The range of variation for elements in the lithogeochemistry samples are as follows: Au from 2 to 46000 ppb, Ag from 40 to 9080 ppb, As from 7 to 134 ppm, Cu from 21 to 601 ppm, Pb from 4 to 1485 ppm. The highest Au and Ag anomalies are associated with hornblende monzodiorite porphyry and monzonite porphyry. Type of the mineralization, as disseminated and associated with hydrothermal breccia, the extent of alteration and its relation with lithology and structural geology indicate the presence of an epithermal gold deposit.

---

Firouzkuh prospect area is located about 35 km northeast of Torbat-e- Jam, Khorasan Razavi Province. Geology of the area includes metamorphosed rocks of Miankouhi Formation, which has intruded by monzogranitic to dioritic intrusions. The magnetic susceptibility of the intrusive rocks varies from 0 to 43 ´ 10^-5 SI and they belong to reduced granitoids of ilmenite series. These rocks are affected by sericitic, silicification, and propylitic alterations in some places. Geochemistry of intrusive rocks indicates that they vary from metaluminous to peraluminous and belong to medium-K to high-K calc-alkalin and shoshonite series. Tectonic setting of intrusions is pre-plate collision to post-collision uplift. Mineralization has controlled by fault zone and formed in the contact between intrusive rocks and metasandstones or in metamorphosed units. Primary minerals consist of gold, arsenopyrite, pyrite, chalcopyrite, and pyrrhotite and secondary minerals include covellite, hematite, and goethite. Geochemical exploration, using chip composite method, shows anomalies of Au (up to 8942ppb), As (up to 74500 ppm), Cu (up to 357 ppm), Pb (up to 45 ppm), and Zn (up to 97 ppm) in the surface samples of the area, which are related to vein mineralization. Core drilling geochemistry indicates that maximum contents of Au (30732 ppb) and Cu (3200 ppm) exist in OBH-7 and high anomaly of As (98670 ppm) and W (133 ppm) are in OBH-2. Au often shows a positive correlation with As in most samples. It mainly exists in arsenopyrite and less as native gold or pyrrhotite and pyrite minerals. Based on presence of reduced intrusive rocks of ilmenite series, reduced mineral assemblages (arsenopryrite and pyrrhotite), type and development of alteration, mineralization form and high concentrations of Au, Cu, As, and W, the area can be part of a reduced intrusion-related gold system, which requires further investigations.

---

Shurchah antimony deposit is located in flysch zone of eastern Iran. The antimony mineralization was formed in silicic veins that hosted by highly silicified and brecciated granitoids and low-grade metamorphic rocks which are rich in phyllosilicate minerals. Stibnite is the most aboundant Sb-bearing ore mineral in the veins and is associated with pyrite, chalcopyrite, arsenopyrite and gold. Senarmontite and cervantite are antimony oxides present in the deposit. The host rocks were potentially able to cause the acidification needed to induce stibnite-gold mineral precipitation. Based on paragenetic relations and thermodynamic data, stibnite is the stable antimony phase in the study deposit and its deposition is controlled by temperature decrease and reduction, except under alkaline conditions where acidification is the principal cause of mineralization. Both stibnite and gold can be transported in appreciable concentrations in the form of bisulfide complexes and their deposition occurred by pH decreases. Homogenization temperature and salinity of fluid inclusions in quartz crystals associated with mineralized veins, are 146.5 to 327.9˚C and 0.21 to 5.71 wt.% NaCl eq. respectively suggesting a meteoric origin for ore-bearing fluid and these values confirm  the epithermal to mesothermal type of mineralization.

---

Keybarkuh is located about 70 Km southwest of Khaf city (Khorasan Razavi Province) in the northeast of the Lut block. Rock units in the area comprises of slate, phyllite, schist and recrystalized limestone with Paleozoic age that was intruded by granite to diorite as dikes and stocks of Cretaceous to Tertiary age. Based on magnetic susceptibility, intrusive bodies are oxidant and reducing which the oxidant bodies mostly having alteration and mineralization. The eastern Keybarkuh oxidant bodies are of Midlle Eocen, related to subduction environment of continental margin, often high-K to shoshonitic and metaluminous. Propylitic alteration zones with broader area and sericitic, argillic and silicic with less distribution were observed in the southern area. Mineralization is seen in the contact of intrusive bodies or in joint and fractures of them as veins and veinlets in south of the area. Veins and veinlets with northwest to southeast strike, 70 to 80 degrees dip to the northeast have thickness upto half meter. They can be divided into two sets: 1-Veins and veinlets associated with galena, sphalerite and barite as primary minerals, which formed the first generation of mineralization. 2- Veins and veinlets associated with pyrite, chalcopyrite and quartz as primary minerals; covellite, bornite, chalcocite, malachite, azurite and iron oxides (magnetite, hematite and limonite) as secondary minerals which is the second generation of mineralization. Paragenetic sequences of minerals and relationship between minerals are indicative of a hydrothermal activity and deposition of the above mentioned minerals in at least two stages in the upper part of oxidant intrusive bodies. Geochemical exploration of stream sediment show anomalous Cu (68 ppm), lead (1691 ppm), zinc (320 ppm), barium (5003 ppm) and the rock also show anomalous Cu (3%), gold (2657 ppb), silver (ppm 160), lead (4%), zinc (2159 ppm), barium (1466 ppm) bismuth (1767 ppm) and Mo (66 ppm) in the southern parts of the area which are relatively high.

---

The Simorgh area is located about 113 km southwest of Nehbandan. Initial prospecting conducted by satellite data ASTER sensor with spectral angle mapper method, in order to identify probable alteration zones. The data, compared with field observations, have provided satisfactory results. This area consists of Eocene volcanic units in which various sub volcanic rocks have intruded in them. The major alteration includes propylitic, argillic, silicified and sericitic. Mineralzation at the surface is observed in the form of disseminated and hydrothermal breccias. The maximum distributed gold element is 93 ppb, Arsenic 35 ppm and molybdenum 33 ppm. Disseminated mineralization, associated with hydrothermal breccias, widespread alteration and their relationship with lithology and structural geology indicates the presence of a type of epithermal gold deposit hosted breccia.

---

The Baghuo gold mine (Kuhzar) is located about 100 km S-SE of Damghan. The area is part of Torud- Chahshirin volcano- plutonic belt. The hosts of quartz – tourmaline veins are mainly granite, granodiorite and volcanic rocks such as andesite and dacite.  Mineralization occurs as a copper- gold bearing silica vein. Quartz, pyrite, chalcopyrite, gold, hematite, malachite, azurite, covellite and Fe- hydroxides ore are main constituents of mineralized veins. Gold grains with <50 µm in diameter commonly occurr within quartz grains. Based on petrography studies, six types of fluid inclusions in quartz were distinguished: (1) monophase liquid inclusions; (2) monophase vapor inclusions (3) two- phase inclusions of liquid-rich; (4) two- phase inclusions of vapor-rich; (5) three- phase halite-bearing inclusions; (6) poly-phase inclusions. Fluid inclusion studies show homogenization temperatures ranging from 250 to 400 °C with salinities from 4 to 30 wt% equivalent NaCl. Data shows that the evolution of mineralizing fluid occurred at a depth of more than 600 m below the surface and pressure about 100 bar. Evidences suggest that Baghu area mineralization may have occurred at the epithermal condition related to a porphyry system.

---

The Zarshuran Carlin-type gold deposit is located about 30 km north of Takab, West-Azarbaidjan Province, NW Iran. Interaction between the ore-forming fluids and the host carbonates and shales resulted in development of the decarbonatization, argillic, alunite, silicic, and sulfide alteration zones in the study area. Based on mesoscopic and microscopic studies on drill core samples, gold mineralization is mainly associated with Au-bearing pyrite and arsenic-containing pyrite generated during two stages. The mineral assemblages associated with these stages are As-bearing pyrite, realgar, orpiment, cinnabar, stibnite, and colloform sphalerite together with lesser amounts of sulfosalts (tetrahedrite and getchellite) intergrown with jasperoid and quartz. The microthermometric studies on liquid-rich 2-phase fluid inclusions in euhedral quartz crystals intergrown with the Au-bearing sulfides showed that the ore-forming fluids had an average  homogenization temperature (T_h) and salinity of about  260°C and 9.2 wt% NaCl equivalent, respectively. The variation trends in salinity and T_h of fluid inclusions could be explained by a combination of mixing and dilution of ore-bearing fluids with subsurface waters of meteoric origin. These processes were likely the principal cause for instability of Au-bearing complexes and hence gold deposition in the veins/veinlets. In addition, on the basis of the obtained pressures from microthermometric data the estimated depths for ore formation were within the range of 160 to 300 meters correlated with 40 to 75 bars, which is in agreement with some known Carlin-type gold deposits. In general, the geological, mineralogical, textural, and microthermometric data provided sufficient evidence to categorize the gold mineralization at Zarshuran as ­­­­­­­Carlin-type