Geochemistry And Petrology Of Granophyric Granite Veins Penetrated In The Igneous Intrusive Complex In South Of Qorveh Area, West Iran

Abstract: Qorveh area (west Iran) belongs to the Sanandaj-Sirjan zone. Igneous activity resulted from subduction of Neo-Tethys beneath Iran microplate during Mesozoic and Cenozoic produced several intrusive and extrusive rocks throughout Sanandaj-Sirjan zone that convoluted intrusive complex in south of the study area is one of them. This complex is generally comprised of diorite, gabbro, monzonite, quartz-monzonite and quartz-monzodiorite. Several garnophyric granite veins penetrated into the diorite and gabbro in the complex. These granite veins are metaluminous (A/CNK=0.66-0.9), alkalic and have I-type and A-type granitiod geochemical characteristics. These samples have moderate REE contents ( REE=83-147 ppm), negative Eu anomaly (Eu/Eu * =0.4-0.7), high field strength elements (HFSE) Nb, Ta, Ti… contents ( HFSE=70-130 ppm) and high light rare earth elements to heavy rare earth elements (LREE/HREE) ratios (average 6 ppm). Basis on the mineralogical, petrological and geochemical studies, it is clear that crystal plays an important role in generation of this rock. Also, granite samples possess geochemical signatures of active continental margin (enriched in large ion lithophile elements (LILE) Rb, K, U, Sr, Cs and Th with respect to Nb and Ti) and a post-orogenic geodynamic environment

Petrography and Geochemistry of Porphyroid Granitoid Rocks in the Alvand Intrusive Complex, Hamedan (Iran)

Abstract: Alvand granitoid complex with emplacement age upper to middle Jurassic (153-167 Ma) in Sanandaj-Sirjan zone, into intruded Hamedan schistes. This complex is located with 40 km length and 10 km width in south and west Hamedan. Alvand porphyroid granitoids based on lithological composition are granodiorite, monzogranite, syenogranite and alkali-feldspar granite. Based on mineralogical characteristics consist of mineral assemblages plagioclase, quartez, K-feldspar and biotite. Geochemically, these rocks are calc-alkaline series and based on saturation degree of aluminum (ASI) are peraluminous. The mineralogical, lithological, and geochemical studies indicate that the Alvand porphyroid granitoids have S-type characteristics. These rocks displays the geochemical characteristics typical of magmatic arc intrusions related to an active continental margin

Mineralogy, chemistry of magnetite and genesis of Korkora-1 iron deposit, east of Takab, NW Iran

Introduction There is an iron mining complex called Shahrak 60 km east of Takab town, NW Iran. The exploration in the Shahrak deposit (general name for all iron deposits of the area) started in 1992 by Foolad Saba Noor Co. and continued in several periods until 2008. The Shahrak deposit comprising 10 ore deposits including Korkora-1, Korkora-2, Shahrak-1, Shahrak-2, Shahrak-3, Cheshmeh, Golezar, Sarab-1, Sarab-2, and Sarab-3 deposits )Sheikhi, 1995) with total 60 million tons of proved ore reserves. The Fe grade ranges from 45 to 65% (average 50%). The ore reserves of these deposits vary and the largest one is Korkora-1 with 15 million tons of 55% Fe and 0.64% S. The Korkora-1 ore deposit is located in western Azarbaijan and Urumieh-Dokhtar volcanic zone, at the latitude of 36°21.8´, and longitude of 47°32´. Materials and methods Six thin-polished sections were made on magnetite, garnet, and amphibole for EPMA (Electron Probe Micro Analysis). EPMA was performed using a JEOL JXA-733 electron microprobe at the University of New Brunswick, Canada, with wavelength-dispersive spectrometers. Results and discussion Outcropped units of the area are calc-alkaline volcanics of rhyolite, andesite and dacite and carbonate rocks of Qom Formation in which intrusion of diorite to granodiorite and quartzdoirite caused contact metamorphism, alteration plus skarnization and formation of actinolite, talc, chlorite, phlogopite, quartz, calcite, epidote and marblization in the vicinity of the ore deposit. Iron mineralization formed at the contacts of andesite and dacite with carbonates in Oligo-Miocene. The study area consists of skarn, metamorphic rocks, and iron ore zones. The shape of the deposit is lentoid to horizontal with some alteration halos. The ore occurred as replacement, massive, disseminated, open-space filling and breccia. The ore minerals of the deposit include low Ti-magnetite (0.04 to 0.2 wt % Ti), minor apatite, and sulfide minerals such as pyrite and chalcopyrite. Magnetite is the most important mineral and has 0.2 to 4 mm grain size and partly transformed into hematite, limonite and goethite. In some places, magnetite can be seen as euhedral grains in hand specimen. Supergene minerals such as chalcocite, malachite, azurite, and covellite are also present. Hematite formed as primary and secondary types in which primary type occurred in deeper parts of the ore body along with magnetite and has lamellar texture with up to 0.2 mm grain size. Meanwhile, secondary type of hematite formed from martitization along magnetite grain boundaries and fractures. In the surface area of the deposit, ore minerals strongly altered to mixtures of oxide and hydroxide minerals (ochre) like goethite, hematite, limonite and lepidochrocite which changed the color of the ore body to yellow, deep orange, red and brown. Pyrite is the most important sulfide mineral and formed in three stages. In the first stage, pyrite occurred with magnetite and has 0.1 to 0.3 mm subhedral to anhedral grains which altered to oxide and hydroxide minerals. At the second stage, pyrite has 0.2 to 1 mm euhedral grains, occurred between the magnetite and gangue minerals and converting to chalcopyrite. At the third stage, pyrite with magnetite, calcite and quartz filled fractures as open-space fillings and are pretty unaltered. The skarn zone includes garnet, pyroxene, secondary calcite, epidote, and chlorite and the metamorphic zone includes marble. Sericitization, silicification, calcitization, chloritization-epidotization, argilitization, propylitization and actinolitizion are the important alterations in the area from which chloritization-epidotization and calcitization in the ore and propylitic alteration in the volcanics are dominant. The EPMA analytical results on 30 points on magnetite and hematite suggest that the amount of Ti and V (0.004 wt % and 0.002 wt % in average, respectively) are low in contrary to Mn and Al (0.33 wt % and 5.32 wt % in average, respectively). Therefore, it fits in the skarn ore deposit domain in Ni/(Cr + Mn) versus Ti + V and Ca + Al + Mn versus Ti + V discrimination diagrams of iron ore deposits (Beaudoin et al., 2007). High Mn in the rock samples of Korkora-1 can be resulted from substitution of Fe+2 by Mn+2 in magnetite structure that can be a sign of hydrothermal skarn. Titanium, Mn, V and Zn show a positive correlation and Al, Cu, Mg, P, Si, Ca, Ni and Cr show a negative correlation with Fe. According to the chemistry of magnetite and plotting them on V2O5 versus TiO2 and V2O5 versus Cr2O3 diagrams, it can be recognized that the samples of Korkora-1 deposit resemble exoskarn magnetite of Goto deposit. The analysis of goethite of Korkora-1 show the amount of 2.5 to 4 wt % SiO2, 76 wt % Fe, and Ni (110 ppm) without Ti and Cr in its structure. Mineralographical and geochemical evidence from ore, occurrence of iron in contact with carbonates and skarn mineralogy such as garnet, pyroxene, secondary calcite, epidote and chlorite suggest iron skarn genesis for Korkora-1 deposit. Fluids generated from intrusive bodies like diorite and quartz-diorite with variations in physicochemical conditions, produced skarn in contact with carbonates and volcanic rocks. The heat from intrusive bodies caused recrystallization of carbonates and formed marbles in the footwall of the deposit. Meteoric water has also less important contribution in the ore-forming fluids. Fluid inclusion studies show existing of two types of fluids, a low salinity (10 wt % NaCl equiv.) and a medium salinity (25 to 30 wt % NaCl equiv.) fluid. Mixing magmatic and meteoric waters makes decreasing in the temperatures and deposition of ore fluids. The Korkora-1 deposit formed in four stages: 1) intruding the intrusive bodies, 2) entering Fe and SiO2 into Qom carbonates and forming calc-silicates, 3) mixing magmatic and meteoric fluids, hydrolysis of calc-silicates, consuming H+, instability of Fe complexes and deposition of iron oxides, 4) retrograde alterations of hydrous and non-hydrous calc-silicates with low temperature and high fO2 fluids and forming chlorite, calcite, clay minerals and hematite. Acknowledgements We gratefully thank Mr. Reza Sheikhi from Saba Noor Co. who kindly helped us during the research. We also thank Professor David Lentz from University of New Brunswick for advising and supporting the research. References Sheikhi, R., 1995. Economic geology study of Shahrak Fe deposit, east of Takab. M.Sc. Thesis, Shahid Beheshti University, Tehran, Iran, 161 pp. (in Persian with English abstract) Beaudoin, G., Dupuis, C., Gosselin, P. and Jebrak, M., 2007. Mineral chemistry of iron oxides: application to mineral exploration. In: C.J. Andrew (Editor), Ninth Biennial SGA meeting, SGA, Dublin, pp. 497−500. <br

The mass balance calculation of hydrothermal alteration in Sarcheshmeh porphyry copper deposit

Sarcheshmeh porphyry copper deposit is located 65 km southwest of Rafsanjan in Kerman province. The Sarcheshmeh deposit belongs to the southeastern part of Urumieh-Dokhtar magmatic assemblage (i.e., Dehaj-Sarduyeh zone). Intrusion of Sarcheshmeh granodiorite stock in faulted and thrusted early-Tertiary volcano-sedimentary deposits, led to mineralization in Miocene. In this research, the mass changes and element mobilities during hydrothermal process of potassic alteration were studied relative to fresh rock from the deeper parts of the plutonic body, phyllic relative to potassic, argillic relative to phyllic and propylitic alteration relative to fresh andesites surrounding the deposit. In the potassic zone, enrichment in Fe2O3 and K2O is so clear, because of increasing Fe coming from biotite alteration and presence of K-feldspar, respectively. Copper and molybdenum enrichments resulted from presence of chalcopyrite, bornite and molybdenite mineralization in this zone. Enrichment of SiO2 and depletion of CaO, MgO, Na2O and K2O in the phyllic zone resulted from leaching of sodium, calcium and magnesium from the aluminosilicate rocks and alteration of K-feldspar to sericite and quartz. In the argillic zone, Al2O3, CaO, MgO, Na2O and MnO have also been enriched in which increasing Al2O3 may be from kaolinite and illite formation. Also, enrichment in SiO2, Al2O3 and CaO in propylitic alteration zone can be attributed to the formation of chlorite, epidote and calcite as indicative minerals of this zone

Mineralogy and electron microprobe studies of magnetite in the Sarab-3 iron Ore deposit, southwest of the Shahrak mining region (east Takab)

Introduction There is an iron mining complex called Shahrak 60 km east of the Takab town, NW Iran. The exploration in the Shahrak deposit (general name for all iron deposits of the area) started in 1992 by the Foolad Saba Noor Co. and continued in several periods until 2008. The Shahrak deposit is comprised of 10 ore deposits including Sarab-1, Sarab-2, Sarab-3, Korkora-1, Korkora-2, Shahrak-1, Shahrak-2, Shahrak-3, Cheshmeh and Golezar deposits (Sheikhi, 1995) with a total 60 million tons of proven ore reserves. The Fe grade ranges from 45 to 65% (average 50%). The ore reserves of these deposits are different. Sarab-3 ore deposit with 9 million tons of 54% Fe and 8.95% S is located at the northeast of Kurdistan and in the Sanandaj-Sirjan structural zone at the latitude of 36°20´ and longitude of 47°32´. Materials and methods Sixty thin-polished, polished and thin sections are made for the study of mineralogy and petrology, and among them six thin-polished sections were selected for EPMA (Electron Probe Micro Analysis) on magnetite and hematite. EPMA was performed using the Cameca Sx100 electron microprobe at the Iran Mineral Processing Research Center (IMPRC) with wavelength-dispersive spectrometers. Results and discussion Based on field observations and petrographic studies, lithologic composition of intrusion (Miocene age) ranges within the diorite-leucodiorite, monzodiorite-quartz monzodiorite, granodiorite-granite. With the intrusion of those igneous bodies into carbonate rocks of the Qom Formation, contact metamorphism was formed. The formation of Sarab-3 iron deposit occurred at the three stages of metamorphism, skarnification and supergene. Based on field geology of the deposit, it is composed of endoskarn, exoskarn including Fe ore±sulfides. At the metamorphic stage, after intrusion of intrusive bodies in carbonate rocks, recrystallization took place and marble was formed. With more crystallization of magma, evolved hydrothermal fluids intruded into host rocks. Skarnification occurred at the two stages of progressive and regressive. At the progressive stage, the reaction of fluids and host rocks turned to the formation of anhydrous calc-silicate minerals such as garnet and clinopyroxene. At the regressive stage with the change of physicochemical conditions like decreasing temperature, these minerals converted to hydrous silicates (tremolite-actinolite, epidote) and phyllosilcates (chlorite, serpentine, talk, and phlogopite). Also, minerals such as oxides (magnetite and hematite), sulfides (pyrite and chalcopyrite) and calcite were formed. At a late stage, with activations of fluids, quartz-calcite mineralized veins formed. At the supergene stage, the oxidation process leads to the formation of alteration minerals from the main mineralization. Although there are magnesian minerals in the skarn, its main composition is calcic. The shape of the deposit is lentoid to horizontal and in some places bed formed along with some alteration halos. The ore minerals include low Ti-magnetite (with an average of 0.02 wt % Ti), hematite and sulfide minerals such as pyrite, pyrrhotite and chalcopyrite. Magnetite is the most important mineral with disseminated, vein, open-space filling, aggregate, accumulation, island and cataclastic textures. The magnetite at Sarab-3 is generated in 2 stages: At the first stage, magnetite has mass to mosaic textures that indicate the first phase of deposition in the area and at the second stage magnetite is gray magnetites that are placed as narrow bands around hematite or on the primary magnetite. Hematite in the area is formed either as hypogene hematite with plate or blade texture that is formed before the formation of early magnetite or supergene hematite that itself is formed due to alteration and weathering of magnetite in the superficial and shallow part of the deposit. In the surface area of the deposit, ore minerals are strongly altered to mixtures of oxide and hydroxide minerals like hematite, limonite and goethite which changed the color of the ore body to yellow, deep orange, red and brown. Pyrites are the most important sulfide minerals in the area that are formed in five stages respectively, mass texture (Py1), Melnikovity (py2), vein-veinlet (py3), inclusion (py4), and mineralized veins (py5). Sericitization, calcitization, serpentinization, chloritization, epidotization, uralitization, argilitization, propylitization and actinolitizion are the important alterations in the area from which chloritization-epidotization and calcitization in the ore and propylitic and argilitization alteration in the plutonic rocks are dominant. The EPMA analytical results on 23 points on magnetite and hematite mineral suggest that the amounts of TiO2 and V2O5 (0.03 wt % and 0.01 wt % in average, respectively) are low in contrast to MnO and Al2O3 (0.09 wt % and 1.59 wt % on the average, respectively). Therefore, it fits in the skarn ore deposit domain on Ni/(Cr+Mn) versus Ti+V and Ca+Al+Mn versus Ti+V discrimination diagrams of iron ore deposits (Dupuis and Beaudoin, 2011). High Mn in the rock samples of Sarab-3 may have resulted from the substitution of Fe by Mn in magnetite and hematite structure that can be a sign of hydrothermal skarn. Manganes, Al, Cu, Mg, and Ca show a negative correlation with Fe that may have resulted from the concentration and the substitution of these elements in tremolite-actinolite, epidote, chlorite, calcite, phlogopite and chalcopyrite. According to the chemistry of magnetite and plotting them on V2O5 versus TiO2 and V2O5 versus Cr2O3 diagrams, it can be recognized that the samples of the Sarab-3 deposit resemble to exoskarn magnetite of Goto and endoskarn Karakaen deposit of Senegal. Mineralographical and geochemical evidence from ore, the occurrence of iron in contact with the carbonates and calc silicates such as garnet, pyroxene, secondary calcite, epidote and chlorite suggest iron skarn genesis for the Sarab-3 deposit. References Dupuis, C. and Beaudoin, G., 2011. Discriminant diagrams for iron oxide trace element fingerprinting of mineral deposit types. Mineralium Deposita, 46(4): 319–335. Sheikhi, R., 1995. Economic geology study of Shahrak Fe deposit, east of Takab. M.Sc.Thesis, Shahid Beheshti University, Tehran, Iran, 161 pp. (in Persian with English abstract

Fluid inclusion and sulfur stable isotope evidence for the origin of the Ahangran Pb-Ag deposit

Introduction The Ahangaran Pb-Ag deposit is located in the Hamedan province, west Iran, 25 km southeast of the city of Malayer . . The deposit lies in the strongly folded Sanandaj-Sirjan tectonic zone, in which the ore bodies occur as thin lenses and layers. The host rocks of the deposit are Early Cretaceous carbonates and sandstones that are unconformably underlain by Jurassic rocks. Ore minerals include galena, pyrite, chalcopyrite, pyrrhotite and supergene iron oxide minerals. Gangue minerals consist of barite, dolomite, chlorite, calcite and quartz. The mineralization occurs as open-space fillings, veins, veinlets, disseminations, and massive replacements. Alteration consists of silicification, sericitization, and dolomitization. In this study, we carried out studies of mineralogy, microthermometry of fluid inclusions and sulfur isotopes to determine the source of sulfur and the physico-chemical conditions of formation. Materials and methods Seventy samples of different host rocks, alteration, and mineralization were collected from surface outcrops and different tunnels. Twenty of the samples were prepared for mineralogical studies at Tarbiat Modarres University in Tehran and 25 for petrological studies at the University of Bu-Ali Sina. Fluid-inclusion studies were done on 5 samples of quartz and calcite at Pouya Zamin Azin Company in Tehran using a Linkam THM 600 model heating-freezing stage (with a range of -196 to 480ºC). The accuracy and precision of the homogenization measurements are about ±1°C. Salinity estimates were determined from the last melting temperatures of ice, utilizing the equations by Bodnar and Vityk (1994) and for CO2 fluids using equations by Chen (1972). Nine samples of sulfides and barite were crushed and separated by handpicking under binocular microscope and powdered with agate mortar and pestle. About one gram of each sample was sent to the Stable Isotope and ICP/MS Laboratory of Queen’s University, Canada for sulfur isotope analysis. The sulfur isotopes in sulfides and sulfates were run on a Thermo Finnigan Delta Plus XP IRMS mass spectrometer. The analytical uncertainty for δ34S is ±0.2‰. Results and Discussion The main types of fluid inclusions in quartz and calcite are as follows: I: dominant liquid + less vapor (L+V); II: dominant vapor + less liquid (V + L); III: liquid + vapor+ CO2 (L+V+CO2 )(L+V)); IV: CO2 (L+V); V: liquid + vapor + sylvite (L+V+Sy). Homogenization temperatures of primary fluid inclusions indicate that mineralization occurred at temperatures ranging from 130 to 320 °C (ave., 200°C) and their salinites range from 10 to 15 wt % NaCl equiv. The temperatures and salinities of the mineralizing fluids of the Ahangaran deposit are similar to the Irish type Zn-Pb deposits, and suggest a similar origin. The δ34S values of pyrite and galena are within the range of -25.5 to +11.6 ‰ and -6.3 to -8.5 ‰, respectively and for barite are in the range of 26 to 27.2 ‰. These values indicate that the δ34SH2S values of fluids in that deposited the pyrite and galena are within the range of -6.4 to-2.9 ‰ and 9.4 to 27.9 ‰, respectively. The δ34S values of marine sulfate were 13 to 20 ‰ during the Cretaceous (Hoefs, 2009). The δ34S values of barite are near to that of marine sulfate in the Cretaceous which indicate that the sulfate of the barite may have a marine origin. On the other hand, the δ34SH2S values of galena lie within a narrow range, suggesting that the main source of sulfur may be from thermochemical sulfate reduction (TSR). Acknowledgments In this research, we thank Sormak Mines Company for its support during field work. We also thank Sormak Mines Managers, especially Mr. Khakbaz for his cooperation and support of this research. Parts of this research were supported by the research department of Bu-Ali Sina University. We also wish to express our appreciation of the isotopic analyses by Queen's University, Canada. References Bodnar, R.J. and Vityk, M.O., 1994. Interpretation of microthermometric data for H2O-NaCl fluid inclusion. In: B. De Vivo and M.L. Fezzotti (Editors), Fluid inclusions in minerals, Methods and Applications. Virginia Tech, Blacksburg, pp. 117-130. Chen, H.S., 1972. The thermodynamics and composition of carbon dioxide hydrate. M.Sc. Thesis, Syracuse University, Syracuse, New York, 67 pp. Hoefs, J. (translated by Alirezaei, S.), 2009. Stable Isotope Geochemistry. Springer Verlag, Berlin, 332 pp. (in Persian) <br

Rare earth element (REE) partitioning in amphibole-bearing medium grade metamorphic rocks from the Alvand Complex (Sanandaj-Sirjan Zone, NW Iran)

In this work we explore the distribution of rare earth elements (REE) in hornblende-bearing metamorphic rocks from the Jurassic Alvand plutonic complex (Sanandaj-Sirjan Zone, NW Iran) focusing on the understanding the effect of rock-forming silicates in controlling compositional variations during metamorphism. The studied rocks contain two distinct amphibole-dominated paragenesis: a first one including hornblende + epidote + plagioclase (“amphibolite”) and a second on made up of hornblende + garnet + epidote + plagioclase (“garnet amphibolite”). The bulk high Al2O3 (average 17.7 wt%), CaO (average 11.9 wt%) and low Fe2O3* (average 5.9 wt%), MgO (average 2.3 wt%), and TiO2 (average 0.8 wt%) contents together with the Zr/Ti (average 280), Na2O/ Al2O3 (average 0.05) and Na2O+K2O (average 1.7 wt%) values indicate these rocks are para-amphibolite formed by metamorphism of a marl (calcareous shale) protolith. With respect to the rock-forming phases, the epidotes have the highest ΣREE contents (ΣREE=86-210 ppm). The garnets (ΣREE=27-87 ppm) and hornblendes (ΣREE=10-22 ppm) have moderate values, whereas the plagioclase shows the lowest REE (2-4.7 ppm) amounts. Inverse and forward modelling thermobarometry was applied to unravel the pressure-temperature history of the studied samples and therefore to reveal the impact of each phase on the REE partitioning during the recorded metamorphic evolution, considering that REE are mostly immobile during crust processes and therefore their bulk budget is that of the protolith