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Journal of Economic Geology
Introduction The Ni-laterites were mostly derived from ultramafic rocks in ophiolite complexes during weathering in tropical climate. Lateritization processes result in leaching of some major elements (Si and Mg) from the source rocks and... more
Introduction
The Ni-laterites were mostly derived from ultramafic rocks in ophiolite complexes during weathering in tropical climate. Lateritization processes result in leaching of some major elements (Si and Mg) from the source rocks and concentration of some others (Ni, Fe, Cr and Co) in the residual soils. The Ni-bearing laterites are divided into three major subgroups including oxides, silicates and clay types (Berger et al., 2011). Hematite and goethite are the main constituents of the oxides type, whereas garnierite is the main carrier for Ni in silicates type. In the clay laterite, saponite and smectite are the main Ni-carriers.
The Bavanat region contains Ni-bearing laterites as discontinuous outcrops which have formed on ophiolite ultramafic rocks in the northeast Fars province. These ultramafics are remnants of Neo-Tethys oceanic lithosphere which have been emplaced on continental margin along the Zagros Suture Zone in the Late Cretaceous era (Rajabzadeh, 1998). These laterites have recently attracted some geologists to work on them (e.g. Khademi and Hasheminassab, 2010; Rasti and Rajabzadeh, 2017). The aim of this study is to determine the effects of pH, organic matter (OM) and weathering intensity on the geochemical and mineralogical characteristics of Ni-laterites in the Chesmeh Rostami area, Bavanat region.

Materials and methods
Sampling was carried out along three geological cross sections on undisturbed laterite profiles. The samples were studied using refracted and reflected light microscopic methods. Nine of the representative samples were analyzed using XRD and ICP-MS methods at the Iran Minerals Processing Research Center. PH and OM values of the samples from different soil horizons were determined using routine analytical methods.

Results
An undisturbed laterite profile consists of four major horizons from base to top including protolith, saprolite, transitional and oxide zones. pH values vary in a narrow range through the soil profiles. The minimum (6.82) and maximum (7.99) values were determined just in the weathering front at the top of the protolith and at the top of oxide horizon, respectively. In the same way, OM of the soils increases from protolith (0.140 wt.%) to the oxide zone (1.475 wt.%).
Protolith is generally a decomposed harzburgite that appears in dark green color. It mainly consists of lizardite with relicts of olivine and orthopyroxene and minor amounts of quartz, clinochlore and hematite. Protolith traditionally transforms to saprolite. The latter is easily discriminated by its softness in field and its light green to gray color. Lizardite and quartz are the major minerals which are accompanied with amorphous iron oxy-hydroxides and silica. Transitional zone is located as a narrow zone between saprolite below and oxide horizon above. No relicts of the source rock are preserved here. It appears as a soil of yellow to orange in color. XRD data from this horizon indicated that calcite and hematite are present as major phases along with minor lizardite and quartz. Oxide horizon is a very soft and porous dark to light red soil that has 12m thickness. This horizon mainly consists of hematite, goethite and clinochlore with variable amounts of amorphous silica and iron oxides.
Geochemically, Fe2O3 (8.31-25.75 wt.%), MnO (0.11-0.27 wt.%), Ni (1898-6793 ppm), Co (40-152 ppm) and Cr (131-3985 ppm) concentrations increase continuously from base to top of the laterites. There is good correlation between Ni and Fe2O3. On the contrary, silica (41.17 to 37.17 wt.%) and MgO (18.45 to 10.97 wt.%) contents decrease from base towards the top of laterites.
Chemical Index of Alteration (CIA), Chemical Index of Weathering (CIW) and Rate Weathering (RW) were used in determination of the weathering intensity during lateralization processes. The calculated data indicated that weathering intensity is medium to weak in the Bavanat region.

Discussion
Ni-bearing laterites in the Bavanat region were formed during weathering of the ophiolite ultramafic rocks at semi-tropical conditions. Four major horizons were formed through vertical profiles of the laterites. However, low concentration of Ni in the source rock by one side and medium to weak intensity of weathering by other side result in production of low-grade Ni-laterites. This is confirmed by pH values and remnants of chromite grains in the protolith horizon. However, weathering causes decomposition of the source rocks resulting in weak liberation of elements. Some elements such as Si and Mg have leached away, but high values of OM and pH at the top of the soils helped Fe fixation (Kabata- Pendias and Pendias, 1999; Thorne et al., 2009). Good correlation between Fe and Ni indicates that iron oxides and hydroxides play the role of scavenger for Ni. Mobility of Ni decreases in the presence of OM and high pH. It thus adsorbs on the Fe compounds. The Ni-laterites in the Bavanat are classified in oxide type clan.

Acknowledgments
The authors would like to thank the Research Council of Shiraz University for financial support of this work.       

References
Berger, V.I., Singer, D.A., Bliss, J.D. and Moring, B.C., 2011. Ni- Co Laterite Deposits of the World-databaseand Grade and Tonnage Models. U.S. Geological Survey, Reston, Virginia, 30 pp.
Kabata-Pendias, A. and Pendias, H., 1999. Biogeochemistry of trace elements. Polish Scientific Publishing Company (PWN), Warsaw, Poland, 400 pp.
Khademi, A. and Hasheminassab, M., 2010. Study on mining potential of Ni-laterites from Ghader Abad, Fars province. 29th symposium of Earth Sciences, Tarbiat Moallem University Tehran, Tehran, Iran. (in Persian with English abstract)
Rajabzadeh, M.A., 1998. Mineralisation en chromite et elements du groupe du platine dans les ophiolites d’Assemion et de Neyriz centrure du Zagros, Iran. Ph.D. Thesis, Institue National Polytechnique de Lorraine, Nancy, France, 358 pp.
Rasti, S. and Rajabzadeh, M.A., 2017. Mineralogical and Geochemical Characteristics of Serpentinite-Derived Ni-Bearing Laterites from Fars Province, Iran: Implications for the Lateritization Process and Classification of Ni-Laterites. International Journal of Environmental, Chemical, Ecological, Geological and Geophysical Engineering, 11(7): 541–546.
Thorne, R., Herrington, R. and Roberts, S., 2009. Composition and origin of the Çaldağ oxide nickel laterite, W. Turkey. Mineralium Deposita, 44(5): 565–581.
Introduction The Robaie copper area is located 95 kilometers South of Damghan in the Semnan province. The study area has coordinates between 54˚30΄37˝to 54˚30΄42.71˝ latitude and 35˚22΄29.41˝ to 35˚23΄47.54˝ longitude. Geotectonically,... more
Introduction
The Robaie copper area is located 95 kilometers South of Damghan in the Semnan province. The study area has coordinates between 54˚30΄37˝to 54˚30΄42.71˝ latitude and 35˚22΄29.41˝ to 35˚23΄47.54˝ longitude. Geotectonically, the study area is located in the central Iran and in the northern part of the Torud-Chahshirin volcanic-plutonic belt (Houshmandzadeh et al., 1978). The Torud-Chahshirin volcanic-plutonic belt is a Tertiary magmatism in central Iran which is composed of volcanic rocks with dominant andesite composition and granodiorite intrusive with dominant diorite composition (Fard et al., 2001). Torud-Chahshirin volcanic-plutonic belt has created a favorable geological situation for base metals such as copper, lead, zinc, gold, silver and other precious and base metals, such as the Robaie copper area, Chah Messi (Cu±Pb-Zn; Imamjome et al., 2009), Kuh-Zar (Cu-Au; Rohbakhsh et al., 2018) and other instances. The main objective of this study is geology, petrography, U-Pb zircon dating and Sr-Nd isotope and also alteration, mineralization, geochemistry and fluid inclusion in the study area.

Materials and methods
60 samples were collected from the study area. Petrographic studies were done on 40 thin sections. Mineralization and paragnesis of the system were studied based on 10 polished-thin sections and 6 polished sections. The measurements were conducted on a Linkam THMSG 600 at the Ferdowsi University of Mashhad. REE (ICP-MS method-ACME Laboratory in Vancouver, Canada) elements were analyzed for 3 samples of diorite dykes. Eight  sampels for geochemistry and four samples for fire assay were analyzed at the Zar Azma Company. U-Pb dating in zircon of diorite dyke was conducted by the ICP-MS method in the Arizona LaserChron Center. Sr and Nd isotopic compositions were determined at the Laboratório de Geologia Isotópica da Universidade de Aveiro, Portugal.

Results
The geology of the area is dominated by volcanic rocks (andesite and trachyandesite), which were intruded by diorite dykes. Alteration zones are propylitic, argillic, sericitic and carbonate. The Copper deposit in the study area occurs as ore veins situated along fault zone with NS-SW trending. Vein thickness varies from 1-5m. Vein thickness varies from 1-5m. The primary minerals are chalcopyrite, pyrite and chalcocite, covellite, bornite, malachite, azurite, hematite, goethite and limonite are secondary minerals. The amount of Cu is between 0.01 to 5.6 % and amount of Ag, Sb, Pb, Zn, As elements is low. The homogenization temperature (Th) values ranged from 165 to 300 oC. Salinities of ore-forming fluids ranged from 7 to 16 wt. % NaCl equivalents. Diorite dykes in the Robaie area have characteristics of enrichment in LREE versus HREE, enrichment of LILE and depletion in HFSE. The initial 87Sr/86Sr and 143Nd/144Nd ratios of biotite-hornblende diorite are 0.705664 and 0.512486, respectively. The εNdI value is -1.7. In the εNdI versus initial 87Sr/86Sr diagram diorite dykes of the Robaie area plot to the right part of the mantle array. The mean age of diorite dyke is 50.49±0.49 Ma. Therefore, the U-Th-Pb zircon dating indicates that diorite dyke formed in the early Eocene (Ypresian) era.

Discussion
Diorite dykes originated from mantle-derived magmas. The parental melt would have originated in a non-depleted mantle source. Isotopic data from diorite dykes show that subduction source with contamination to continental crust. In tectonic setting diagrams (Pearce et al., 1984) diorite dykes plot on the fields of the volcanic arc granites (VAG). In the Dy/Yb vs. Dy system (Shaw, 1970) diorite dykes of Robaie area were formed by 15-20% partial melting of spinel-phlogopite lherzolite. According to Yh/Yb vs. Ta/Yb (Pearce et al., 1984) and Ba/La vs. Th/Nd diagrams (Shaw, 1970) diorite dykes were formed from slab-drive fluid in the active continental margins.
Fluid inclusions data of the Robaie area manifest that the ore-forming fluids were medium to low temperature and medium to low salinity. The pressure determined for the Robaie area was approximately < 10 MPa, which is equivalent to a depth of approximately < 1 km assuming lithostatic pressure. Fluid inclusion studies indicate that there is a positive correlation between homogenization temperature and fluid salinity, similar to the process of fluid mixing. The decrease in salinity has been the most important factor in the precipitation of copper in the area. All of evidence shows that mineralization in the Robaie area is of epithermal type deposit.
Introduction The study area is located in the Khorasan Razavi Province, NW of Gonabad between 58° 33˝- 58 ° 38˝ to the east and 25° 34˝ - 25° 38˝ to the north. Geotectonically, the area is located in the northern part of the Lut Block.... more
Introduction
The study area is located in the Khorasan Razavi Province, NW of Gonabad between 58° 33˝- 58 ° 38˝ to the east and 25° 34˝ - 25° 38˝ to the north. Geotectonically, the area is located in the northern part of the Lut Block. The Lut Block is the main metallogenic province in the east of Iran (Karimpour et al., 2012). There is a significant outcrop of Tertiary intermediate volcanic and pyroclastic rocks in the northwest of Gonabad. This region is rich in clay (kaolin) mineralization. The source of these kaolin deposits (argillic alteration) is related to a granitic dyke that intruded into the Shemshak Formation.

Geology
According to studies most of the rocks in this region are volcanic rocks which mainly consist of trachyte, andesite, trachyandesite, dacite, rhyodacite, pyroclastics rocks of agglomerate and tuff and some subvolcanic masses and dykes of acidic to intermediate compositions. Sedimentary rocks in the study area are slightly metamorphosed. The oldest metamorphic rock is exposed in the south- east of the study area which consists of Jurassic slates and quartzite. At this area green schist facies have led to the formation of slate and quartzite. The intrusive bodies, composition are monzogranite porphyry to diorite porphyry. The main fault zones which make specific types of structure are strike-slip.

Alteration and mineralization
The volcanic and subvolcanic rocks have been affected by hydrothermal fluids via the phenomenon which has caused alteration in the rocks. The alteration zones are propylitic, silicification, argillic, and quartz-sericite-pyrite. The silicification has occurred with higher intensity in the northern and central parts of the investigated area. Propylitic alteration has spread all over the area with higher intensity in the northwest and southern parts of the study area. The clay mineral deposits (argillic zones) have been mined. The mineralogical compositions of this clay deposits are quartz, kaolinite, dickite, montmorillonite and hematite.

Materials and Methods
Ten doubly polished wafers (0.3mm thick) of fluorite, barite and quartz crystals were prepared for fluid inclusion studies, and examined petrographically. They were studied using standard techniques (Roedder, 1984, 1992) and Linkam THM 600 heating–freezing stage (from -190 to 600 °C) mounted on an Olympus TH4–200 microscope stage at the Ferdowsi University of Mashhad, Iran.
The accuracy is estimated to be ±0.2 °C on freezing, ±2 °C below 350 °C and about ±4 above 350 °C on heating. The salinity of the fluids trapped in fluid inclusions is calculated based on the temperature of final ice melting (Tm) and the equation of Bodnar (1993). Densities are calculated using the Flincor software according to microthermometric data (Brown and Lamb, 1989).

Discussion
Microthermometeric investigations were conducted on 126 fluid inclusions in two types of liquid-rich (L+V) fluids in silicified cap of Rokhsefid and Baghsia kaolin mines. Homogenization experiments revealed a temperature range of 186–326 °C for the studied inclusion. Salinity variations could not be determined because of the small amount of fluids. The homogenization temperature and depth of formation from the first type of inclusions are 186- 256°C and 250 meters, respectively. The second type of inclusions have Th between 275 to 326°C and are 500 meter in depth. Microthermometric study of fluid inclusions on quartz-sericite-pyrite and sulfide- silicified mineralization in Kalatehno indicates that two types of hydrothermal fluids were important in the formation of mineralization. These two types are involved. First, Th between 289- 354 °C, salinity range from 10.86 to 10.98 wt.% NaCl equivalent, and the average depth of about 600 meters. Second, Th between 266- 377°C, salinity ranges from 11.7 to 13.07 wt.% NaCl equivalent, and average depth of about 600 meters. Microthermometric study of the fluid inclusions in fluorite veins were conducted on fluorite, barite and quartz minerals. The results obtained from the fluorites indicate Th between 184- 360°C, and Salinity ranges from 0 to 3.2 wt.% NaCl equivalent. Fluid inclusion studies consisting of quartz veins and quartz- sulfide- copper carbonate in Kalatehno copper mineralization involve two types of fluids with homogenization temperatures and salinity range from 260- 300 °C and 1.5- 3.23 wt.% NaCl equivalent and 193- 240 °C and 4.1- 5.86 wt.% NaCl equivalent.

Conclusion
Fluid inclusion studies on fluorite samples have shown a temperature homogenizations (Th) between 186-326 °C. These studies indicate the average formation temperature of 280°C for argillic alteration. Fluid inclusion studies on Kalateno Cu mineralization show two types of mineralization fluids with the temperatures of 193 to 240 and 260 to 300°C with salinity between 1.5-3.23 wt. % 4.1- 5.86 wt.% NaCl equivalent, respectively. The temperature ranges obtained are similar to those of epithermal systems.
Introduction The Iranian plateau is part of the Alpine-Himalayan orogenic belt, which consists of several continental fragments separated from each other by major boundary faults and/or ophiolitic suture zones (Gansser, 1981). Generally,... more
Introduction
The Iranian plateau is part of the Alpine-Himalayan orogenic belt, which consists of several continental fragments separated from each other by major boundary faults and/or ophiolitic suture zones (Gansser, 1981). Generally, the tectonic evolution of Iran has been controlled by the opening and closure of the Proto-Tethys, Paleo-Tethys and the Neo-Tethys during the Precambrian-Cambrian, Paleozoic and Cenozoic, respectively.
The study area is located in the northwest of Iran (the Kurdistan province) and 20 km northeast of the city of Saqez. This area is a part of the northern Sanandaj-Sirjan Zone (Aghanabati, 2005). This belt is response to opening and subduction of Neo-Tethyan oceanic crust beneath the Central Iran (Alavi, 1994). During Cretaceous-Tertiary eras, numerous granitoid bodies were formed in this belt. The Saheb granitoid is one of these granitoid bodies which mainly consists of monzogranite, quartz monzonite and quartz monzodiorite. The aim of this research study is to discuss the evolution of the Late Cretaceous-Early Paleocene Saheb granitoids in the Sanandaj-Sirjan zone based on geology, petrography and geochronology results.

Material and methods
In this study, 70 rock samples were collected from different types of intrusive rocks from which 30 thin sections were prepared for petrographic studies. Furthermore, four samples from the granitoid bodies (quartz monzonite, quartz monzodiorite and monzogranite) were selected for U-Pb dating. Approximately 100 to 150 zircon grains were hand-picked by a binocular microscope from each sample. Cathodo-luminescence imaging and dating of zircon grains were examined at the China University Geosciences (Wuhan branch). Geochronological analysis were performed by using the (LA)-ICP-MS method at the China University Geosciences (Wuhan branch). The detailed analytical method is presented in Liu et al. (2010a, 2010b).

Geology of the study area
The Saheb granitoid body is located in the Sanandaj-Sirjan zone. According to the geological map of Chapan (scale: 1/100000, Kholghi khosraghi, 1999), the Precambrian to Quaternary units are exposed in the study area. The oldest units are the Kahar, Bayandor and Soltanieh Formations with Precambrian to Cambrian age. The Permian sediments, the Ruteh and Doroud Formations, include sandstone, shale and carbonate. The Jurassic units are found in the northwest of the region, and include sandstones and shale. The Cretaceous sedimentary units are located in the south of the study area. These sediments contain sandstone, limestone, silty-limestone, shale and dolomitic limestone. During Late Cretaceous-Early Paleocene era the Saheb granitoid intruded within the oldest units and caused Fe skarn type deposits in the Saheb area. The Saheb granitoid have been cut by a series of diabasic dikes.

Results
The Saheb granitoid consists of several intrusive bodies containing quartz monzonite, quartz monzodiorite and monzogranite. The major minerals in the quartz monzodiorite consist of plagioclase (35- 40%), quartz (15- 20%), orthoclase (20- 25%), and mafic minerals such as biotite and amphibole (10-15%) with granular texture. The quartz monzonitic rocks show granular and poikilitic textures. Plagioclase (25- 35%), quartz, orthoclase (30- 40%), biotite and amphibole (10-15%) are the main important minerals in the quartz monzonite. Plagioclase (20-25%), quartz (20-30%), orthoclase (30-40%), biotite and amphibole (15%) are the major minerals in the monzogranite.
Zoning in zircon crystals from all four samples is well developed representing their magmatic origin (Hancar and Miller, 1993). Measurements of U-Pb in the Saheb granitoid zircon grains of quartz monzonite samples show their ages to be 62.03±0.56 Ma and 58.9±0.9 Ma. The age of monzogranite is 67.9±1.3 Ma and the age of quartz monzodiorite is 61.1±0.56 Ma. Generally, the age of this granitoid body indicates that the Saheb granitoid has occurred during the Cretaceous- Paleocene time.

Discussion
Based on field and microscopic studies, the Saheb granitoid bodies have been divided into three types of quartz-monzonite, quartz-monzodiorite and monzogranite. The field and mineralogical studies suggest that the Saheb granitoid is an I-type granitoid. The mineralogical variations in this granitoid suggest that the fractional crystallization has played an important role in differentiation of different compositional phases in the Saheb granitoid.
According to the geochronological results, during Late Cretaceous to Early Paleocene, the Saheb granitoid intruded within the Permian and Cretaceous units in the magmatic-metamorphic Sanandaj-Sirjan zone. These granitoids were formed by subduction of Neo-Tethys Ocean beneath the Iranian plateau. It should be mentioned that the intrusion of these granitoids into the Permian carbonates and Cretaceous carbonate and shale caused formation of skarn type iron oxide mineralization.

Acknowledgements
The authors are grateful to the authorities at the University of Zanjan for their financial support. We also thank the authorities at the China University Geosciences (Wuhan branch) for their financial support to perform U-Pb zircon analysis.
Introduction The Chah-Mesi polymetallic vein-type ore deposit, located 40 km north of Shahre-Babak city and 1.5 km southwest of Miduk porphyry copper deposit, is situated in the Dehaj-Sarduieh belt as a part of the Urumieh–Dokhtar... more
Introduction
The Chah-Mesi polymetallic vein-type ore deposit, located 40 km north of Shahre-Babak city and 1.5 km southwest of Miduk porphyry copper deposit, is situated in the Dehaj-Sarduieh belt as a part of the Urumieh–Dokhtar magmatic Arc  (UDMA) (Figure 1).
The main objectives of this research study are to investigate: (1) characterization of multi-element distribution associated with Cu mineralization, in order to demonstrate prediction of elemental concentration applied to identify high-grade ore bodies, (2) evaluating the interrelationships between copper, molybdenum, iron, led, zinc, gold and silver.

Materials and methods
Petrography and mineralography of the Chah-Mesi ore deposit were carried out using thin and polished sections. More than 980 chemical analyses of samples collected from 35 boreholes of the National Iranian Copper Industry Company (NICICO) were implemented to evaluate the statistical as well as spatial distribution and dispersion of multi-element halos. Geochemical data processing was performed by applying Excel (2010), SPSS (19), Datamine (Studio3.22.84.0) and Surfer10 (2011) software packages.

Results
The Chah-Mesi ore deposit consists of four main and some minor polymetalic (Cu-Pb-Zn-Ag) quartz-sulfide veins, with NE-SW and N-S trending and 65-80 degree dipping, which intersected the Eocene volcanic and pyroclastic sequences (Figure 2). It seems that mineralization has mainly occurred along these quartz-sulfide veins overlaid by Quaternary alluvium. Based on rock outcrops, the prominent mineralization has been controlled by structural features including faults and fractures that provided proper conditions for reaction of hydrothermal fluids with the host rocks.
In the Chah-Mesi ore deposit, silicified veins containing poly-metallic mineralization have predominantly occurred along the main faults and shear zones. The intensity of argillic alteration dramatically decreases outward from the mineralized quartz veins (Figure 3). Propylitic alteration which is composed of calcite and chlorite minerals has extended in the peripheral zones and does not represent a clear relationship with Cu mineralization.
The main host rocks in the Chah-Mesi ore deposit consist of basalt to basaltic andesite, with porphyry to glomeroporphyry textures, and to a lesser extent of pyroclastic rocks (Figure 4). The ore bodies are mainly composed of pyrite, chalcopyrite, sphalerite and galena. The ore minerals are accompanied with chalcocite, malachite, covellite, azurite and iron hydroxides that have been formed during supergene and weathering processes (Figure 5). According to field surveys, structural controls have played an important role in the mineralization of the Chah-Mesi ore deposit.
Discussion
Geochemical investigation in the Chah-Mesi ore deposit, using Pearson correlation coefficient of trace elements (Table 1), indicated the highest correlation coefficient (more than 0.7) between Pb-Zn and Ag-Au elements, due to their similar geochemical affinities during epigenetic mineralization. Other significant correlations were observed between Cu-Ag, Cu-Fe, Cu-Au and Fe-Ag with a correlation coefficient of more than 0.6; while the Mo shows weak correlation with other elements. 
Based on cluster analysis, the trace elements that are associated with mineralization can be classified into four main clusters of Pb-Zn, Mo, Cu-Fe-Ag and Au (Figure 6). Noteworthy, despite the fact that Mo and Au each separately form their individual clusters, Au still shows some proximities with the Cu-Fe-Ag cluster that indicate their genetic relationship. However, Mo displays the most dissimilarity with other clusters, which indicates the role of different processes in its distribution. The results of this analysis are well in line with correlation coefficients.
The geochemical vertical zonality of trace elements in the Chah-Mesi ore deposit were studied using four borehole data from different parts of the ore deposit (Figures 7 and 8). This demonstrated that variation of elements at different depths does not follow a uniform pattern due to differences in the type and amount of ore minerals in the veins.
The veins containing lead, zinc and gold mineralization are highly abundant at the shallower levels based on geochemical maps of the Chah-Mesi ore deposit (Figure 9). In contrast, the veins containing copper and silver mineralization have been considerably developed in both shallow and deeper levels. The high degree of Mo at shallow levels seems to occur due to either superimposition of primary geochemical haloes of various veins (Li et al., 1995, 2016) and/or the effect of amount of pyrite, pH, and alkalinity contents of hydrothermal fluids (Leanderson et al., 1987).
The average value of different elements in intervals of 50 meters from the shallow (2500 meters) to the deep (2300 meters) levels are determined by existence of maximum abundance of lead, zinc and gold elements at surface levels. However, the highest average abundance of copper occurs in the deepest level. The highest average value of silver is also located in the 2450, 2350, and 2500 meters levels, which is economically valuable (Table 2). Therefore, the continuation of drilling in the southern part of the Chah-Mesi ore deposit into deeper levels is strongly recommended as there may still exist more concentrations of copper and silver there.

Acknowledgment
The authors are grateful to the honorable personnel of the Miduk Copper Mine for their efforts in providing field studies and access to geochemical analyses.
Introduction The Seh Qaleh agates, located at 120 km NW Birjand, are parts of Central Iranian (Lut block) (Aghanabati, 2004) with geographic coordinates of 58˚ 00′ to 58˚ 30′ longitudes and 33˚ 00′ to 34˚ 00′ latitudes. The host rocks of... more
Introduction
The Seh Qaleh agates, located at 120 km NW Birjand, are parts of Central Iranian (Lut block) (Aghanabati, 2004) with geographic coordinates of 58˚ 00′ to 58˚ 30′ longitudes and 33˚ 00′ to 34˚ 00′ latitudes. The host rocks of the agates are Eocene-Oligocene tuff, andesite and basalt. Silica mineralization in the area has occurred inside the volcanic units in the form of filling cavity and fractures. Here, the agates have very attractive textures such as concentric, flow and dogtooth textures that are accompanied with jasper, amethyst, opal, calcite and gypsum.
Although Seh Qaleh agates are attractive and delightful, with high economical values, there is no scientific research about them. Therefore, their petrography, geochemistry and Raman spectroscopic characteristics are reported in the present paper for the first time.

Materials and methods
More than 400 samples of agates have been collected for this research study and five of these samples were in yellow, white, green, red and black colors. Moreover, four of these rocks were selected for major and trace elements analysis by XRF and ICP-MS. The samples were powdered in Tehran University by a tungsten carbide mill and analyzed in the Zarazma Company (Mashhad). XRD analyses and Raman spectroscopic studies on the agate of the Seh Qaleh area were done in Damghan and Shahrood University of Technology, respectively.

Petrography and Raman spectroscopy
The combination of different analytical techniques such as polarizing microscope, XRD and Raman spectroscopy provided information about the distribution of silica phases in the Seh Qaleh agates. Polarizing microscopy was used here to distinguish between the chalcedony and quartzine fibrous varieties. Moganite has similar optical properties with chalcedony, whose presence in agate is difficult to reveal. Thus, Raman studies were used to investigate these structural disparities. Raman spectroscopic studies showed that moganite and chalcedony can be distinguished based on their different spectral characteristics (Fig. 4, B, C). The use of a focused laser beam (diameter 1 μm) enabled us to analyze the variations in phase composition in the μm-range.
The measurement of Seh Qaleh agates by Raman spectroscopy provided an overview of the quantitative distribution of moganite in the studied samples, in which the fibrous chalcedonies contain more moganite in comparison with nodule chalcedonies (Fig. 4, B, C). The presence and spatial distribution of different silica phases in the Seh Qaleh agates is a result of the primary crystallization processes such as temperature and chemistry conditions (Götze, 2011). Moreover, the presence of moganite and calcite in the Seh Qaleh, confirmed by petrography and XRD studies suggest that the agates had formed in an arid, alkaline environment.

Geochemistry of the agates
Major and trace elements can be incorporated into the agates by substitution of Si by Al, Fe, Na, and Ca and as inclusions or fluid inclusions. The substitution of these elements are limited due to the small number of ions that have similar ionic radii and valence and can substitute for Si4+ in the crystal structure. The Seh Qaleh agates have 95.78 to 98.9 wt.% SiO2 with minor amounts of Al2O3 (0.01-0.34 wt.%), Fe2O3 (0.01-1.07 wt.%), Na2O (0.11-0.15 wt.%), and CaO (0.01-0.4 wt.%), supplied from alteration of the volcanic host rocks.
The high concentrations of U in some of the agates of the study area (especially ~ 38 ppm in the red one) are surprising and propose the operation of specific processes for mobilization, transport and deposition. These processes caused concentrations of U in quartz and chalcedony that can exceed the concentration of U in the Seh -Qaleh volcanic rocks (Table 1).
Zielinski (1979) observed a parallel accumulation of Si and U and investigated the mobility of U during the alteration of volcanic rocks. Based on the theory that the transport of chemical compounds is mainly realized by diffusion processes in aqueous fluids (e.g. Si as monomeric silicic acid Si(OH)4), Porter and Weber (1971) inferred for the uranyl ion a complex with monomeric silica UO2SiO(OH)3+. In addition, the presence of calcite, as associated mineral with silica polymorphs and the concentration of Na, K and Ca elements in agates, indicate that volatile chloride compounds might play a role in the alteration of volcanic rocks as well as the mobilization and transport of SiO2 and other chemical compounds (Götze et al. 2012).

Acknowledgements
Thanks to the Shahrood University of Technology for supporting this project under grants provided by the research council.

References
Aghanabati, S.A., 2004. Iran Geology. Geological Survey of Iran, Tehran, 400 pp.
Götze, J., 2011. Agate-fascination between legend and science. In: J. Zenz (Editor), Agates III. Bode Verlag GmbH, Lauenstein, Germany, pp. 19–133.
Götze, J., Schrön, W., Möckel, R. and Heide, K., 2012. The role of fluids in the formation of agate. Chemie der Erde, 72(3): 283–286.
Porter, R.A. and Weber Jr, W.J., 1971. The interaction of silicic acid with iron (III) and uranyl ions in dilute aqueous solution. Journal of Inorganic and Nuclear Chemistry, 33(8): 2443-2449. Porter, R.A. and Weber Jr, W.J., 1971. The interaction of silicic acid with iron (III) and uranyl ions in dilute aqueous solution. Journal of Inorganic and Nuclear Chemistry, 33(8): 2443–2449.
Zielinski, R.A., 1979. Uranium mobility during interaction of rhyolitic obsidian, perlite and felsite with alkaline carbonate solution. Chemical Geology, 27(1–2): 47–63.
Introduction Iron oxide-apatite deposits (IOA) are considered to be Kirune-type iron ores which have been formed during Proterozoic to Tertiary eras in different parts of the world. They usually have a connection with calc-alkaline... more
Introduction
Iron oxide-apatite deposits (IOA) are considered to be Kirune-type iron ores which have been formed during Proterozoic to Tertiary eras in different parts of the world. They usually have a connection with calc-alkaline volcanic rocks (Hitzman, 2000). Apatite occurs as a major constituent of these deposits which is accompanied with magnetite and some actinolite. One of the most important features of these deposits (Frietsch and Perdahl, 1995) is higher concentration of REEs.
There are some iron oxide-apatite deposits in the Tarom-Hashtjin magmatic-metallogenic belt, northwestern Iran. The Golestan Abad iron oxide-apatite deposit is one of the IOA deposits at the Tarom-Hashtjin belt which is located about 30 km east of Zanjan. The Golestan Abad deposit was studied during the exploration studies, but its geological characteristics, mineralogy, texture, geochemistry and genesis have not been studied yet.

Materials and methods
This research study can be divided into two parts that include field and laboratory studies. Field studies include recognition of different lithological units and mineralization zones along with sampling for laboratory studies. During field studies, 60 samples were selected for petrographical, mineralogical and analytical studies. Moreover, 12 thin sections and 15 thin-polished sections were used for petrographical and mineralogical studies. For geochemical studies, 6 samples from intrusive host rocks and 7 samples from mineralized zones were analyzed by XRF and ICP-MS methods at the Zarazma laboratory, Tehran.

Results
The Golestan Abad area is composed of Eocene volcano-sedimentary rocks of the Karaj Formation which have been intruded by quartz monzodiorite, pyroxene quartz monzodiorite and porphyritic quartz diorite intrusions. Based on petrographic studies, the pyroxene quartz monzodiorites have porphyritic and felsophyric textures and are composed of plagioclase, quartz, clinopyroxene, K-feldspar and hornblende phenocrysts set in a quartz-feldspatic groundmass. Quartz monzodiorites show porphyritic and felsophyric textures and composed of plagioclase, hornblende, quartz, K-feldspar and biotite. The quartz monzodiorite and pyroxene quartz monzodiorites have high-K calc-alkaline affinity and may be classified as metaluminous I-type granitoids. Primitive mantle-normalized (McDonough and Sun, 1995) trace elements diagrams for these granitoids indicate LILE enrichment along with negative HFSE and distinctive positive Pb anomalies. Chondrite-normalized (McDonough and Sun, 1995) REE patterns for these granitoids demonstrate LREE enrichment (high LREE/HREE ratio) and weak negative anomalies in Eu. These granitoids were formed in an active continental margin to post collisional tectonic setting.
Mineralization at the Golestan Abad occurs as lenses and vein-veinlets of iron oxide-apatite mainly within the quartz monzodiorite- pyroxene quartz monzodiorite intrusions. Stockwork ores occur in the footwall of the main veins. Mineralized lenses and veins have up to 300m length and 20m width. Hydrothermal alterations around the mineralized veins include silicification, calcic (actinolitization), argillic and propylitic. From a mineralogical point of view, this deposit is composed of magnetite, apatite, actinolite, pyrite and chalcopyrite as primary minerals, while hematite, covellite, goethite and gypsum were formed during supergene alteration. Mineralization textures in the Golestan Abad deposit include vein-veinlet, banded, massive, brecciated, disseminated, stockwork, replacement, relict and open space filling. Based on mineralogical and textural studies, 3 stages of apatite formation were distinguished which include: 1- coarse-grained idiomorphic apatite crystals within the magnetite matrix, 2- fine-grained apatite crystals as matrix of brecciated magnetites, and 3- coarse-grained idiomorphic apatite crystals within the actinolite-apatite veins which have been cut in the previous stages. Apatite crystals of the 3 mentioned stages have high concentrations of REE that include 0.98, 0.92 and 0.95%, respectively. Condrite-normalized (McDonough and Sun, 1995) REE patterns for 3 apatite generations demonstrate LREE enrichment with high LREE/HREE ratio and distinctive negative Eu anomalies.

Discussion
Similar REE patterns of apatite crystals and mineralized samples with host quartz monzodiorite-pyroxene quartz monzodiorite samples demonstrate a genetic link between iron oxide-apatite mineralization and granitoids. Furthermore, REE patterns of the Golestan Abad deposit are similar to other iron oxide-apatite deposits of the Tarom-Hashtjin metallogenic belt (Nabatian and Ghaderi, 2014; Mokhtari et al., 2017), and those of Central Iranian iron ores (Mokhtari et al., 2013). Finally, the REE patterns of the Golestan Abad deposit are similar with the REE patterns of the Kiruna-type iron ores (Frietsch and Perdahle, 1995). Totally, based on mineralogical assemblages, hydrothermal alteration, mineralization textures and geochemical characteristics, the Golestan Abad iron oxide- apatite deposit can be classified as the Kiruna-type iron ores.

Acknowledgment
This research was made possible by a grant from the office of vice-chancellor for research and technology, University of Zanjan. We acknowledge their support. The respectable reviewers and editor of the Journal of Economic Geology are also thanked for their constructive comments.

References
Frietsch, R. and Perdahl, J.A., 1995. Rare earth elements in apatite and magnetite in Kiruna-type iron ores and some other iron ore types. Ore Geology Reviews, 9(6): 489–510.
Hitzman, M.W., 2000. Iron oxide-Cu-Au deposits: What, where, when and why? In: Porter, T.M., (Editor), Hydrothermal iron oxide copper-gold and related deposits: A global perspective. Vol. 1.  Australian Mineral Foundation, Adelaide, pp. 9–25
Mokhtari, M.A.A., Hossein Zadeh, Gh. and Emami, M.H., 2013. Genesis of iron-apatite ores in Posht-e-Badam Block (Central Iran) using REE geochemistry. Journal of Earth System Science, 122(3): 795–807.
Mokhtari, M.A.A., Sadeghi, M. and Nabatian, Gh., 2017. Geochemistry and potential resource of rare earth element in the IOA deposits of Tarom area, NW Iran. Ore Geology Reveiws, 92: 529–541.
Nabatian, Gh. and Ghaderi, M., 2014. Mineralogy and geochemistry of the rare earth elements in iron oxide-apatite deposits of the Zanjan region. Scientific Quarterly Journal, Geosciences. 24(93): 157–170. (in Persian with English abstract)
Introduction The Sarcheshmeh porphyry copper deposit (PCD) and other porphyry deposits occur in the the most important metallogenic belt in Iran, i.e. the Urumieh-Dokhtar magmatic belt (UDMB). The main phase of intrusion generation in... more
Introduction
The Sarcheshmeh porphyry copper deposit (PCD) and other porphyry deposits occur in the the most important metallogenic belt in Iran, i.e. the Urumieh-Dokhtar magmatic belt (UDMB). The main phase of intrusion generation in various episodes of mineralization in the Sarcheshmeh area is a stock of granodiorite to tonalite (Shahabpour and Kramers, 1987) that is called the Sarcheshmeh porphyry. This stock intruded volcano-sedimentary rocks and alteration has centered on it. The oldest rock units of the area are Eocene volcanic rocks (Waterman and Hamilton, 1975), which are mainly andesites accompanying marine sedimentary rocks that is consistent with a submarine volcano-sedimentary basin environment. Granodiorite and quartz eye porphyry crop out in the northern part of the Sarcheshmeh PCD. The main objective of this study is to investigate their petrology and geotectonic environment.

Materials and Methods
Forty samples from drill cores and surface samples from granodiorite and quartz eye porphyry were collected. Twelve samples were chosen with the lowest degree of alteration (less than 5% of representative samples and low LOI) from amongst them for lithogeochemical analyses by ICP-OES and ICP-MS. Lithogeochemical analysis of the main elements was carried out using ICP-OES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) by lithiumborate fusion, and elemental analysis of trace and rare earth elements was performed by ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) using sodium peroxide fusion in the SGS Company, Toronto, Canada.

Results and Discussion
Based on the Na2O+K2O versus SiO2 values on Cox et al. (1979) and Middlemost (1985) diagram, also R1-R2 diagram of De la Roche et al. (1980), the samples were plotted in the field of granodiorite and quartz diorite. On Harker diagrams, the contents of FeOt, CaO, P2O5, Al2O3, MgO, and TiO2 versus SiO2 show a decreasing pattern. Decreasing amounts of MgO and TiO2 can be related to early crystallization of ferromagnesian minerals and of CaO, Al2O3, and P2O5 to plagioclase and apatite crystallization, respectively. The chemical relationship and continuous pattern of the samples indicate that they probably resulted from fractionation of a unique magma. On the basis of the AFM diagram, they have calc-alkaline affinities. These observations and the presence of magnetite and other opaque minerals indicate high ƒO2 crystallization throughout fractionation stages. The samples of the study area were plotted in the calc-alkalic and alkali-calcic fields on a Frost et al. (2001) diagram and indicate that they are mainly magnesia consistent with oxidized I-type magmas.
The spider-diagrams show negative anomalies in HFSE (especially Ti and Nb) and positive anomalies in LILE (especially in Ba and Rb). Negative anomalies of HFSE such as Ti, Nb, P and Ta can be related to the subduction of the Arabian plate under Central Iran and reflect the chemistry of the origin and crystallization-melting processes during evolution of the rocks. Moreover, it can be concluded that these elements remained in the source during partial melting, which is characteristics of I-type arc-related magmas. The behavior of LILE can be attributed to the behavior of fluid phases that were involved during the subduction. The REE diagrams show enrichment of LREE relative to HREE which can also be attributed to the subduction of the Arabian plate under Central Iran. Shafiei et al. (2009) and Asadi, 2018 proposed post-collision environment for the PCDs of the UDMB, especially in the Kerman part.
By studying on the Dehaj-Sarduieh belt, Dargahi et al. (2010) concluded that the time of collision of the Arabian plate and the Central Iran continental plate was Late Eocene, and the Sarcheshmeh porphyry stock emplaced in post-orogenic environment like other stock porphyries of the UDMB. The samples of the Sarcheshmeh PCD plot in the mature arc area based on Rb vs Y+Nb diagram and it can be envisaged that they are related to the post-collision magmatic arc.

References
Asadi, S., 2018. Triggers for the generation of post–collisional porphyry Cu systems in the Kerman magmatic copper belt, Iran: New constraints from elemental and isotopic (Sr-Nd-Hf-O) data. Gondwana Research, 64(12): 97–121.
Dargahi, S., Arvin, M., Pan, Y. and Babaei, A., 2010. Petrogenesis of post-collisional A-type granitoids from the Urumieh-Dokhtar magmatic assemblage, southwestern Kerman, Iran: Constraints on the Arabian-Eurasian continental collision. Lithos, 115(1–4): 190–204.
Shafiei, B., Haschke, M. and Shahabpour, J., 2009. Recycling of orogenic arc crust triggers porphyry Cu mineralization in Kerman Cenozoic arc rocks, southeastern Iran. Mineralium Deposita, 44(3): 265–283.
Shahabpour, J. and Kramers, J.D., 1987. Lead isotope data from the Sarcheshmeh porphyry copper deposit, Kerman, Iran. Mineralium Deposita, 22(4): 278–281.
Waterman, G.C. and Hamilton R., 1975. The Sarcheshmeh porphyry copper deposit. Economic Geology 70(3): 568–576.