University of Isfahan Petrological Journal 2228-5210 14 4 2024 02 20 Physicochemical conditions of crystallization based on the composition of amphibole-Plagioclase pair in the Gowd-e-Howz (Siah-Kuh) granitoid, Baft, Kerman Physicochemical conditions of crystallization based on the composition of amphibole-Plagioclase pair in the Gowd-e-Howz (Siah-Kuh) granitoid, Baft, Kerman 1 28 28203 10.22108/ijp.2024.139533.1311 FA Mahbube Arabzadeh Bani Asadi Ph.D. Student, Faculty of Earth Sciences, Shahrood University of Technology, Iran, Habibollah Ghasemi Professor, Faculty of Earth Sciences, Shahrood University of Technology, Iran, Samuel Angiboust Associate Professor, Earth Sciences Department, Ecole Normale Supérieure de Lyon, France, Mehdi Rezaei-Kahkhaei Associate Professor, Faculty of Earth Sciences, Shahrood University of Technology, Iran, Clothilde Minnaert-Thefo M.Sc. Student, Earth Sciences Department, Ecole Normale Supérieure de Lyon, France, Journal Article 2023 10 21 The Lower Jurassic Gowd-e-Howz (Siah-Kuh) granitoid Massif (≈180 Ma) is located in the southern part of Sanandaj-Sirjan metamorphic-magmatic zone 60 km SE of of Baft, south of Kerman. The Massif is one of the most important magmatic signs of subduction initiation of the Neotethys oceanic basin since the Late Triassic. In spite of several studies have been carried out regarding this massif and its cutting dikes (e.g., Malekizadeh, 2000; Ghanbarzadeh, 2011; Arvin et al., 2007), but none of them has been studied the rock-forming minerals chemistry and their physicochemical crystallization conditions. The tendency to use the composition of calcic amphiboles to understand the processes governing magmatic systems is due to their widespread presence in a wide range of subduction-related mafic-intermediate-felsic calc-alkaline high-potassium extrusive and intrusive igneous rocks that make them suitable for geothermobarometery. Amphiboles are stable in a wide range of temperature (400 to 1150 °C) and pressure (1 to 23 kbar) conditions (Blundy and Holland, 1990). For this reason, we have used the chemical data of minerals, in particular, amphiboles and feldspars of different rocks of Gowd-e-Howz granitoid Massif in different geothermobarometers (e.g., Hammarstrom and Zen, 1986; Hollister et al., 1987; Johnson and Rutherford, 1989; Schmidt, 1992; Holland and Blundy, 1994; Anderson and Smith, 1995; Stein and Dietl, 2001; F´em´enias et al., 2006; Ridolfi et al., 2010, 2016; Ridolfi and Renzulli, 2012; Molina et al., 2015; Putirka, 2016). Geology The Gowd-e-Howz granitoid stock belonging to Late Triassic (Sabzehei et al., 1998; Arvin et al., 2007) represents a magmatic product of subduction initiation in the Zagros Neotethys realm, although, Nazemzadeh and Rashid (2006) is assigned it to post Cretaceous. Based on geological map of Hadji-Abad (Sabzehei et al., 1998), detailed geological surveying of this research, whole rock Rb-Sr dating (≈199 Ma, Arvin et al., 2007) and U-Pb datings on the separated zircons (≈180 Ma, Arabzadeh Baniasadi, in press), it was intruded the Upper Paleozoic Sargaz-Abshour metamorphic complexes (mainly amphibolite, marble and schists) and the Triassic igneous-sedimentary rocks. The Lower Jurassic terrigenous rocks (equivalent to the Shemshak Formation in Alborz and Central Iran Zones) and the Lower Cretaceous limestones covered the Triassic rock units. The Gowd-e-Howz composite granitoid stock has three main parts including gabbro/diorite, granodiorite, and granite as well. The first phase of magma injection in the margins was of gabbro/diorite type. The second phase as the main part of the stock was the intrusion of granodioritic magma into the diorites. It has dark mafic microgranular/micro granitoid enclaves (MMEs). The third phase was a gray to pink color granite-alkali granite that intruded the granodiorite part. Finally, the quartz monzonite dikes cut the whole of the stock. This composite granitoid stock has normal compositional zoning of the granitoids involving the mafic suites in the margins, intermediates in the middle, and the felsic suites in the central part. Research Methods In situ chemical analyses of minerals of the Gowd-e-Howz granitoid Massif were carried out at GFZ Potsdam (Germany) using a JEOL-JXA 8230 microprobe equipped with five WDS. The operating conditions were as follows: 15 kV accelerating voltage, 20 nA beam current, and 10 s counting time on peak position for Si, K, Cr, Na, P or 20 s counting time for Al, Ca, Fe, Mn, Mg, Ti, F, Cl. Detection limits are 0.02–0.9 wt%. Petrography The granitoid rocks are characterized by essential mineals of plagioclase, pyroxene, amphibole, alkali feldspar, biotite, quartz, opaques, apatite, sphene. Among the secondary minerals of the Gowd-e-Howz granitoid stock, calcite, epidote, chlorite, sericite, and clays are of particular interest. The common textures are anhedral granular, intergranular, and sometimes perthitic, granophyric, graphic, and myrmekitic textures. The occurrence of very beautiful graphic, worm-like myrmekitic and granophyric textures display the rapid simultaneous intergrowth of quartz, alkali feldspar, and plagioclase from an undercooling liquid at relatively shallow depths (Best, 2003; Vernon, 2004; Philpotts and Ague, 2009). Discussion Chemical compositions of rock-forming minerals have been analyzed to study the petrogenesis and physicochemical conditions of crystallization and final replacement of study intrusion. For this purpose, we present the amphiboles and feldspars chemical data. The amphiboles are of calcic type, mostly with hornblende composition, and oxidant belonging to calc-alkaline subduction zone magmatic series. Feldspar compositions range from oligoclase (Ab97.50An1.50Or1) to labradorite (Ab39An60.50Or0.50). Applying the various geothermobarometric calculation methods based on amphibole-plagioclase pair and single amphibole yield temperatures of 742 °C to 769 °C at pressures of 2 to 2.8 kbars, equivalent to the depth of 5-7 Km to cease the cation exchange and establish the minerals equilibrium(closing temperatures) and final emplacement of the stock in the continental crust. Also, oxygen fugacity in the magma chamber was high at the time of amphiboles crystallization (logfO2≈-13). Conclusion Amphiboles and feldspars are the main rock-forming minerals of the Gowd-e-Howz granitoid massif. The in situ chemical analysis of these minerals shows that the composition of feldspars varies from oligoclase in granites to labradorite in diorites. Amphiboles are the low-pressure calcic group, with the dominant composition of hornblende, and oxidant belonging to calc-alkaline magmatic series of subduction zones crystallized under high oxygen fugacity and equilibrated with the feldspars at temperatures of 742 to 769 °C and pressures of 2 to 2.8 kbars equivalent to pressures of 5 to 7 Km depths. Acknowledgments The authors are grateful to the Vice-Chancellor of Research and staff of the Shahrood University of Technology and the Microprobe Laboratory of the Potsdam University (Germany), and anonymous reviewers of the Petrological Journal for valuable comments and critical reviews of this manuscript. The Lower Jurassic Gowd-e-Howz (Siah-Kuh) granitoid Massif (≈180 Ma) is located in the southern part of Sanandaj-Sirjan metamorphic-magmatic zone 60 km SE of of Baft, south of Kerman. The Massif is one of the most important magmatic signs of subduction initiation of the Neotethys oceanic basin since the Late Triassic. In spite of several studies have been carried out regarding this massif and its cutting dikes (e.g., Malekizadeh, 2000; Ghanbarzadeh, 2011; Arvin et al., 2007), but none of them has been studied the rock-forming minerals chemistry and their physicochemical crystallization conditions. The tendency to use the composition of calcic amphiboles to understand the processes governing magmatic systems is due to their widespread presence in a wide range of subduction-related mafic-intermediate-felsic calc-alkaline high-potassium extrusive and intrusive igneous rocks that make them suitable for geothermobarometery. Amphiboles are stable in a wide range of temperature (400 to 1150 °C) and pressure (1 to 23 kbar) conditions (Blundy and Holland, 1990). For this reason, we have used the chemical data of minerals, in particular, amphiboles and feldspars of different rocks of Gowd-e-Howz granitoid Massif in different geothermobarometers (e.g., Hammarstrom and Zen, 1986; Hollister et al., 1987; Johnson and Rutherford, 1989; Schmidt, 1992; Holland and Blundy, 1994; Anderson and Smith, 1995; Stein and Dietl, 2001; F´em´enias et al., 2006; Ridolfi et al., 2010, 2016; Ridolfi and Renzulli, 2012; Molina et al., 2015; Putirka, 2016). Geology The Gowd-e-Howz granitoid stock belonging to Late Triassic (Sabzehei et al., 1998; Arvin et al., 2007) represents a magmatic product of subduction initiation in the Zagros Neotethys realm, although, Nazemzadeh and Rashid (2006) is assigned it to post Cretaceous. Based on geological map of Hadji-Abad (Sabzehei et al., 1998), detailed geological surveying of this research, whole rock Rb-Sr dating (≈199 Ma, Arvin et al., 2007) and U-Pb datings on the separated zircons (≈180 Ma, Arabzadeh Baniasadi, in press), it was intruded the Upper Paleozoic Sargaz-Abshour metamorphic complexes (mainly amphibolite, marble and schists) and the Triassic igneous-sedimentary rocks. The Lower Jurassic terrigenous rocks (equivalent to the Shemshak Formation in Alborz and Central Iran Zones) and the Lower Cretaceous limestones covered the Triassic rock units. The Gowd-e-Howz composite granitoid stock has three main parts including gabbro/diorite, granodiorite, and granite as well. The first phase of magma injection in the margins was of gabbro/diorite type. The second phase as the main part of the stock was the intrusion of granodioritic magma into the diorites. It has dark mafic microgranular/micro granitoid enclaves (MMEs). The third phase was a gray to pink color granite-alkali granite that intruded the granodiorite part. Finally, the quartz monzonite dikes cut the whole of the stock. This composite granitoid stock has normal compositional zoning of the granitoids involving the mafic suites in the margins, intermediates in the middle, and the felsic suites in the central part. Research Methods In situ chemical analyses of minerals of the Gowd-e-Howz granitoid Massif were carried out at GFZ Potsdam (Germany) using a JEOL-JXA 8230 microprobe equipped with five WDS. The operating conditions were as follows: 15 kV accelerating voltage, 20 nA beam current, and 10 s counting time on peak position for Si, K, Cr, Na, P or 20 s counting time for Al, Ca, Fe, Mn, Mg, Ti, F, Cl. Detection limits are 0.02–0.9 wt%. Petrography The granitoid rocks are characterized by essential mineals of plagioclase, pyroxene, amphibole, alkali feldspar, biotite, quartz, opaques, apatite, sphene. Among the secondary minerals of the Gowd-e-Howz granitoid stock, calcite, epidote, chlorite, sericite, and clays are of particular interest. The common textures are anhedral granular, intergranular, and sometimes perthitic, granophyric, graphic, and myrmekitic textures. The occurrence of very beautiful graphic, worm-like myrmekitic and granophyric textures display the rapid simultaneous intergrowth of quartz, alkali feldspar, and plagioclase from an undercooling liquid at relatively shallow depths (Best, 2003; Vernon, 2004; Philpotts and Ague, 2009). Discussion Chemical compositions of rock-forming minerals have been analyzed to study the petrogenesis and physicochemical conditions of crystallization and final replacement of study intrusion. For this purpose, we present the amphiboles and feldspars chemical data. The amphiboles are of calcic type, mostly with hornblende composition, and oxidant belonging to calc-alkaline subduction zone magmatic series. Feldspar compositions range from oligoclase (Ab97.50An1.50Or1) to labradorite (Ab39An60.50Or0.50). Applying the various geothermobarometric calculation methods based on amphibole-plagioclase pair and single amphibole yield temperatures of 742 °C to 769 °C at pressures of 2 to 2.8 kbars, equivalent to the depth of 5-7 Km to cease the cation exchange and establish the minerals equilibrium(closing temperatures) and final emplacement of the stock in the continental crust. Also, oxygen fugacity in the magma chamber was high at the time of amphiboles crystallization (logfO2≈-13). Conclusion Amphiboles and feldspars are the main rock-forming minerals of the Gowd-e-Howz granitoid massif. The in situ chemical analysis of these minerals shows that the composition of feldspars varies from oligoclase in granites to labradorite in diorites. Amphiboles are the low-pressure calcic group, with the dominant composition of hornblende, and oxidant belonging to calc-alkaline magmatic series of subduction zones crystallized under high oxygen fugacity and equilibrated with the feldspars at temperatures of 742 to 769 °C and pressures of 2 to 2.8 kbars equivalent to pressures of 5 to 7 Km depths. Acknowledgments The authors are grateful to the Vice-Chancellor of Research and staff of the Shahrood University of Technology and the Microprobe Laboratory of the Potsdam University (Germany), and anonymous reviewers of the Petrological Journal for valuable comments and critical reviews of this manuscript.

https://ijp.ui.ac.ir/article_28203_44e0a7f6fc914bdf897785b842af0a26.pdf

University of Isfahan Petrological Journal 2228-5210 14 4 2024 02 20 Mineral chemistry and thermobarometry of peridotites in Dalampar ophiolite (Northeast Oshnavieh): implication to petrogenetic evolution and tectonomagmatic setting Mineral chemistry and thermobarometry of peridotites in Dalampar ophiolite (Northeast Oshnavieh): implication to petrogenetic evolution and tectonomagmatic setting 29 74 28381 10.22108/ijp.2024.140774.1322 FA Ayoub Vaisy Ph.D. Student, Department of Mineral Resource and Groundwater, Faculty of Earth Sciences, Tehran, Iran, Mohammad Rahgoshay Professor, Department of Mineral Resource and Groundwater, Faculty of Earth Sciences, Tehran, Iran, Iman Monsef Assistant Professor, Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences, Zanjan, Iran, Bahman Rahimzadeh Assistant Professor, Department of Mineral Resource and Groundwater, Faculty of Earth Sciences, Tehran, Iran, Journal Article 2024 02 20 Ophiolites are slices of oceanic lithosphere obducted onto a continental margin and can be classified as mid-oceanic ridge (MOR) or suprasubduction zone (SSZ) types based on the tectonic setting in which they originally formed (Pearce et al., 2000; Shervais, 2001). The Zagros Orogen extends from eastern Turkey through northern Iraq and northwest of Iran to the Hormuz Strait and Oman (Alavi 1994; McQuarrie, 2003; Homke et al., 2004; Agard et al., 2005; Shafaii Moghadam et al., 2018). The geodynamic evolution of the Zagros Belt is mainly related to the opening and closure of the Neo-Tethys oceanic basin. Ophiolites, as Neotethys oceanic lithosphere remnants, are emplaced along the Zagros Orogen. These ophiolites are emplaced along two main belts (Saccani et al., 2013; Shafaii Moghadam et al., 2018). The Neo-Tethys suture zone coincides with the Main Zagros thrust fault (Agard et al., 2005) and ophiolites are exposed scattered along this zone. Regional Geology The Dalampar ophiolite, located between the Piranshahr and Salmas ophiolites. The Dalampar ophiolites consist mainly of strongly sheared serpentinized ultramafic rocks including harzburgite, dunite overlaid by gabbro and basalt units. The emplacement mechanism of the Dalampar ophiolite massifs into the Iranian microcontinent and structural evolution is completely unknown. There has been not performed a systematic investigation of these ophiolites and geodynamic and relation with other ophiolites are not well Studied. Thus, the main purpose of the present paper is to investigate the petrogenetic processes, tectono-magmatic environment, using mineral chemistry and textural evidences of Dalampar ophiolite which are fundamental for understanding the tectonic evolution of the Neo-Tethyan Ocean. Material and Methods During the fieldwork, a number of suitable peridotites samples with least alteration effects were selected. Folloing the petrographic studies, a thin polished section was prepared from several harzburgites for microprobe analysis using JEOL JXA-8600 M model,15 kv accelerator voltage and 2-ray current 10-8 Amp, placed at the Department of Earth Sciences and Environment of Yamagata University, Japan. Result and Discussion Harzburgites are the most basic and widespread ultramafic units in Dalampar ophiolite complex. They show evidences including the presence of exsolution of clinopyroxene in orthopyroxene, the orientation and elongation of the crystals indicating these rocks were formed in the upper mantle conditions and reached equilibrium in the crustal environment. Exsolutions of clinopyroxene lamellae from orthopyroxene are one of the textures observed in the rocks under study and is widespread in both abyssal and SSZ peridotites (Tamura and Arai, 2006). The Cr# of spinel in abyssal peridotites is a good indicator of the degree of partial melting for the mantle-derived spinel peridotite. Low Cr# spinels represent less depleted peridotites, whereas the high Cr# spinels highlight more depleted peridotites (Dick and Bullen, 1984; Arai, 1994). in the Mid-oceanic ridges, the degrees of partial melting and depletion are generally low. In contrast, the supra-subduction zone peridotites have a high degree of partial melting and depletion (Niu and Hekinian, 1997). The content of Cr# in presented Cr-spinels are high (78-83%), and associated with boninitic melts formed by high degrees of partial melting or much more extensive melt-rock reaction (Arai, 1994). As the the Cr# of spinel versus the Fo content of olivine diagram shows the harzburgites fall in SSZ domain. Furthermore, all rock types fall into olivine-spinel mantle array (OSMA). This is regarded as the evidence for their residual origin, i.e. they form a trend which was likely caused by partial melting. Experimental studies confirm that the Al2O3 and TiO2 contents, as well as FeO/MgO ratios in chromian spinel are directly related to those of the parental melt (Rollinson, 2008). According to Maurel and Maurel (1982), The Al2O3 contents of the parental melt range from 10 to 11 wt. % for the studied Harzburgites. Such values are consistent with boninitic melts, which typically contain 10–14 wt.%, respectively (Dilek and Thy, 2009). In the Cr# versus TiO2 diagram, the Dalampar peridotites classify as depleted peridotites. In consequence, chemistry of the chromian spinels in the Dalampar peridotites are compatible with a genesis in a suprasubduction zone from boninitic or primitive arc magmas. However, forearc regions may contain both SSZ and abyssal peridotites, although the former are typically dominant (Pearce et al., 2000). Olivine-spinel and orthopyroxene-clinopyroxene thermobarometry in the harzburgites shows equilibrium temperatures of 1000-1100 ºC at a pressure of 28 kbar and suggests that they have been equilibrated in spinel peridotite field. Conclusion The Dalampar Ophiolitic Complex as a part of the Tethyan ophiolites is exposed in the northwestern part of the Iranian-Azerbaijan province, extending to the Anatolian ophiolites in southeastern Turkey. The petrography, geochemistry and microstructural studies of the residual mantle sequence in Dalampar Ophiolitic Complex provide important information regarding the degree of partial melting and deformation in the oceanic mantle lithosphere. Mineral chemistry clearly indicate that Dalampar ultramafic rocks record an episode of boninitic magmatism occurred within the southern Neo-Tethys Ocean in the Late Cretaceous. Boninitic melts in Dalampar Ophiolites were formed by partial melting of depleted peridotite, a residue after MORB-type melt extraction. Mineral chemical data indicate that SSZ peridotites are the residues from ∼30–40% of mantle melting. Nonetheless, the very low (< 0.25 wt. %) TiO2 calculated for the parental melt in equilibrium with chromian spinel are only consistent with boninitic-type parental melts. Based on geothermobarometry calibration the temperature and pressure of crystallization of harzburgite rocks were 1000 to 1200 ° C and 24 Kbar, corresponding to the SSZ tectonic environment. Ophiolites are slices of oceanic lithosphere obducted onto a continental margin and can be classified as mid-oceanic ridge (MOR) or suprasubduction zone (SSZ) types based on the tectonic setting in which they originally formed (Pearce et al., 2000; Shervais, 2001). The Zagros Orogen extends from eastern Turkey through northern Iraq and northwest of Iran to the Hormuz Strait and Oman (Alavi 1994; McQuarrie, 2003; Homke et al., 2004; Agard et al., 2005; Shafaii Moghadam et al., 2018). The geodynamic evolution of the Zagros Belt is mainly related to the opening and closure of the Neo-Tethys oceanic basin. Ophiolites, as Neotethys oceanic lithosphere remnants, are emplaced along the Zagros Orogen. These ophiolites are emplaced along two main belts (Saccani et al., 2013; Shafaii Moghadam et al., 2018). The Neo-Tethys suture zone coincides with the Main Zagros thrust fault (Agard et al., 2005) and ophiolites are exposed scattered along this zone. Regional Geology The Dalampar ophiolite, located between the Piranshahr and Salmas ophiolites. The Dalampar ophiolites consist mainly of strongly sheared serpentinized ultramafic rocks including harzburgite, dunite overlaid by gabbro and basalt units. The emplacement mechanism of the Dalampar ophiolite massifs into the Iranian microcontinent and structural evolution is completely unknown. There has been not performed a systematic investigation of these ophiolites and geodynamic and relation with other ophiolites are not well Studied. Thus, the main purpose of the present paper is to investigate the petrogenetic processes, tectono-magmatic environment, using mineral chemistry and textural evidences of Dalampar ophiolite which are fundamental for understanding the tectonic evolution of the Neo-Tethyan Ocean. Material and Methods During the fieldwork, a number of suitable peridotites samples with least alteration effects were selected. Folloing the petrographic studies, a thin polished section was prepared from several harzburgites for microprobe analysis using JEOL JXA-8600 M model,15 kv accelerator voltage and 2-ray current 10-8 Amp, placed at the Department of Earth Sciences and Environment of Yamagata University, Japan. Result and Discussion Harzburgites are the most basic and widespread ultramafic units in Dalampar ophiolite complex. They show evidences including the presence of exsolution of clinopyroxene in orthopyroxene, the orientation and elongation of the crystals indicating these rocks were formed in the upper mantle conditions and reached equilibrium in the crustal environment. Exsolutions of clinopyroxene lamellae from orthopyroxene are one of the textures observed in the rocks under study and is widespread in both abyssal and SSZ peridotites (Tamura and Arai, 2006). The Cr# of spinel in abyssal peridotites is a good indicator of the degree of partial melting for the mantle-derived spinel peridotite. Low Cr# spinels represent less depleted peridotites, whereas the high Cr# spinels highlight more depleted peridotites (Dick and Bullen, 1984; Arai, 1994). in the Mid-oceanic ridges, the degrees of partial melting and depletion are generally low. In contrast, the supra-subduction zone peridotites have a high degree of partial melting and depletion (Niu and Hekinian, 1997). The content of Cr# in presented Cr-spinels are high (78-83%), and associated with boninitic melts formed by high degrees of partial melting or much more extensive melt-rock reaction (Arai, 1994). As the the Cr# of spinel versus the Fo content of olivine diagram shows the harzburgites fall in SSZ domain. Furthermore, all rock types fall into olivine-spinel mantle array (OSMA). This is regarded as the evidence for their residual origin, i.e. they form a trend which was likely caused by partial melting. Experimental studies confirm that the Al2O3 and TiO2 contents, as well as FeO/MgO ratios in chromian spinel are directly related to those of the parental melt (Rollinson, 2008). According to Maurel and Maurel (1982), The Al2O3 contents of the parental melt range from 10 to 11 wt. % for the studied Harzburgites. Such values are consistent with boninitic melts, which typically contain 10–14 wt.%, respectively (Dilek and Thy, 2009). In the Cr# versus TiO2 diagram, the Dalampar peridotites classify as depleted peridotites. In consequence, chemistry of the chromian spinels in the Dalampar peridotites are compatible with a genesis in a suprasubduction zone from boninitic or primitive arc magmas. However, forearc regions may contain both SSZ and abyssal peridotites, although the former are typically dominant (Pearce et al., 2000). Olivine-spinel and orthopyroxene-clinopyroxene thermobarometry in the harzburgites shows equilibrium temperatures of 1000-1100 ºC at a pressure of 28 kbar and suggests that they have been equilibrated in spinel peridotite field. Conclusion The Dalampar Ophiolitic Complex as a part of the Tethyan ophiolites is exposed in the northwestern part of the Iranian-Azerbaijan province, extending to the Anatolian ophiolites in southeastern Turkey. The petrography, geochemistry and microstructural studies of the residual mantle sequence in Dalampar Ophiolitic Complex provide important information regarding the degree of partial melting and deformation in the oceanic mantle lithosphere. Mineral chemistry clearly indicate that Dalampar ultramafic rocks record an episode of boninitic magmatism occurred within the southern Neo-Tethys Ocean in the Late Cretaceous. Boninitic melts in Dalampar Ophiolites were formed by partial melting of depleted peridotite, a residue after MORB-type melt extraction. Mineral chemical data indicate that SSZ peridotites are the residues from ∼30–40% of mantle melting. Nonetheless, the very low (< 0.25 wt. %) TiO2 calculated for the parental melt in equilibrium with chromian spinel are only consistent with boninitic-type parental melts. Based on geothermobarometry calibration the temperature and pressure of crystallization of harzburgite rocks were 1000 to 1200 ° C and 24 Kbar, corresponding to the SSZ tectonic environment.

https://ijp.ui.ac.ir/article_28381_3b9da234ca86b0b3e3e7d0c4427f8eb8.pdf

University of Isfahan Petrological Journal 2228-5210 14 4 2024 02 20 Exploration criteria at Kahang Cu-Mo porphyry deposit, Isfahan Province Exploration criteria at Kahang Cu-Mo porphyry deposit, Isfahan Province 75 100 28143 10.22108/ijp.2024.139751.1313 FA Hooshang Asadi Haroni Assistant Professor, Department of Mining Engineering Isfahan University of Technology, Isfahan, Iran, Pouya Asadi Harouni M.Sc. Student Department of Mining Engineering, Tehran University, Tehran, Iran, Journal Article 2023 11 10 Porphyry deposits are very important as they contain very large reserves of copper and valuable secondary elements such as molybdenum and gold. Copper-molybdenum or quartz monzonite porphyry deposits are usually structurally related to the magma arc associated with the upper parts of the subduction zone of the continental margin, and copper-gold or porphyry diorite deposits usually form in association with the subduction zone of the island arc (Sillitoe, 2010; Park et al., 2021). Kahang Cu-Mo deposit is located in the middle section of the Urumieyh-Dokhtra magmatic arc. In 2001, Kahang was identified by processing satellite imagery data and mapping hydrothermal alteration by Rio Tinto Mining and Exploration Limited company. Then, a detailed exploration was carried out by Dorsa mining company from 2002 to 2007 and about 40 million tons of copper ore with a grade of 0.6 percent was established (Asadi, 2007). Since 2008, extensive deep drilling has been performed by the National Iranian Copper Company to increase the proved reserve. The main focus of the previous researchers at the Kahang deposit was mostly based on conceptual studies on magmatic character and hydrothermal alterations (Ayati et al., 2008; Harati, 2011; Azadi et al., 2014; Komeili, et al., 2017; Aliyari et al., 2020). In the present research, ASTER satellite imagery data, geological maps, as well as geochemical and magnetic data were processed and used to identify optimum exploration criteria at the Kahang porphyry Cu-Mo deposit and other similar deposits. Geology and mineralization Near-surface mineralization at Kahang deposit is related to altered and brecciated quartz monzonite dykes, and deeper than 200 m is associated with altered quartz monzonite porphyry intrusions showing calk alkaline characteristics. The extensive hydrothermal alteration, from the center to the margin of the Kahang deposit, are phyllic, argillic, and propylitic alterations. Mineralization is mostly related to strong phyllic and potassic alterations. Materials and methods Detailed geological maps of Kahang area were used to identify geological exploration criteria. Aster satellite imagery data of the area was used to identify hydrothermal alterations. ICP analytical results of elements such as Cu, Mo, Zn, and Pb were used to create uni-element and additive index multi-element geochemical anomaly maps to identify geochemical exploration characteristics. In total 16 rock samples were collected for petrographic studies and XRF analysis. A number of 568 magnetic measurements were used to create magnetic anomalies associated with favorable subsurface hydrothermal alterations possibly associated with Cu-Mo mineralization. Geochemical exploration criteria ICP analytical results of the soil samples were used to identify geochemical exploration criteria at Kahang deposit. Basic statical studies were applied to these data to identify the variation of Cu, Mo, Pb, and Zn concentrations in the soil samples that could be associated with subsurface mineralization. Mult-elements additive index geochemical maps of the analytical results of the soil samples showed a Cu-Mo enrichment zone in the central part of the hydrothermal alteration and a Pb-Zn depletion zone in the margin. Based on these additive index maps three porphyry centers were identified at the Kahang deposit for further exploration. Magnetic signature By processing ground magnetic data of the eastern porphyry center at Kahang deposit, residual total magnetic intensity and upward continuation magnetic maps were created to identify magnetic signatures possibly associated with mineralized hydrothermal alterations. These maps showed an ellipsoid-shaped low magnetic anomaly in the eastern porphyry center associated with phyllic alteration hosting Cu-Mo mineralization. These low magnetic anomalies can be used to identify zones of subsurface mineralization at Kahang deposit. Discussion In this research, remote sensing, geological, geochemical, and geophysical studies showed three porphyry centers at Kahang deposit. The world-class economic mineralization only occurred in the eastern porphyry center due to the presence of extensively strongly altered and brecciated quartz monzonite porphyry units showing low magnetic signatures and high Cu-Mo additive index anomalies. By comparing the low magnetic anomalies, high Cu-Mo anomalies, alteration zonation, brecciated rock units, and favorable structures, successful drilling targets can be identified to test subsurface mineralization at Kahang deposit. The integration of this information along with the geochemical and primary drilling information were used to plan systematic drilling. Most of the holes drilled in this zone at depths greater than 150 meters encountered economic mineralization of copper (approximately 0.5%) and molybdenum (approximately 700 ppm). The magmatic arc of Urmia-Dokhtar is considered the most important copper (molybdenum, gold) porphyry province in Iran. Most of the known large porphyry deposits of Iran, such as Sarcheshmeh and Meidok, are located in the southeast of this magmatic arc, and Songun is located in its northwest. In the central part of the Urmia Dokhtar magmatic arc, which is located in Isfahan and Central provinces, no similar deposit was reported prior to the discovery of Kahang deposit. Therefore, these studies have shown that the middle part of this arc may have the potential for many hidden porphyry mineralizations like Kahang deposit. Therefore, the exploration criteria identified in this study can be used for the exploration of similar deposits in this area at various stages of exploration, from identification to detailed exploration. Porphyry deposits are very important as they contain very large reserves of copper and valuable secondary elements such as molybdenum and gold. Copper-molybdenum or quartz monzonite porphyry deposits are usually structurally related to the magma arc associated with the upper parts of the subduction zone of the continental margin, and copper-gold or porphyry diorite deposits usually form in association with the subduction zone of the island arc (Sillitoe, 2010; Park et al., 2021). Kahang Cu-Mo deposit is located in the middle section of the Urumieyh-Dokhtra magmatic arc. In 2001, Kahang was identified by processing satellite imagery data and mapping hydrothermal alteration by Rio Tinto Mining and Exploration Limited company. Then, a detailed exploration was carried out by Dorsa mining company from 2002 to 2007 and about 40 million tons of copper ore with a grade of 0.6 percent was established (Asadi, 2007). Since 2008, extensive deep drilling has been performed by the National Iranian Copper Company to increase the proved reserve. The main focus of the previous researchers at the Kahang deposit was mostly based on conceptual studies on magmatic character and hydrothermal alterations (Ayati et al., 2008; Harati, 2011; Azadi et al., 2014; Komeili, et al., 2017; Aliyari et al., 2020). In the present research, ASTER satellite imagery data, geological maps, as well as geochemical and magnetic data were processed and used to identify optimum exploration criteria at the Kahang porphyry Cu-Mo deposit and other similar deposits. Geology and mineralization Near-surface mineralization at Kahang deposit is related to altered and brecciated quartz monzonite dykes, and deeper than 200 m is associated with altered quartz monzonite porphyry intrusions showing calk alkaline characteristics. The extensive hydrothermal alteration, from the center to the margin of the Kahang deposit, are phyllic, argillic, and propylitic alterations. Mineralization is mostly related to strong phyllic and potassic alterations. Materials and methods Detailed geological maps of Kahang area were used to identify geological exploration criteria. Aster satellite imagery data of the area was used to identify hydrothermal alterations. ICP analytical results of elements such as Cu, Mo, Zn, and Pb were used to create uni-element and additive index multi-element geochemical anomaly maps to identify geochemical exploration characteristics. In total 16 rock samples were collected for petrographic studies and XRF analysis. A number of 568 magnetic measurements were used to create magnetic anomalies associated with favorable subsurface hydrothermal alterations possibly associated with Cu-Mo mineralization. Geochemical exploration criteria ICP analytical results of the soil samples were used to identify geochemical exploration criteria at Kahang deposit. Basic statical studies were applied to these data to identify the variation of Cu, Mo, Pb, and Zn concentrations in the soil samples that could be associated with subsurface mineralization. Mult-elements additive index geochemical maps of the analytical results of the soil samples showed a Cu-Mo enrichment zone in the central part of the hydrothermal alteration and a Pb-Zn depletion zone in the margin. Based on these additive index maps three porphyry centers were identified at the Kahang deposit for further exploration. Magnetic signature By processing ground magnetic data of the eastern porphyry center at Kahang deposit, residual total magnetic intensity and upward continuation magnetic maps were created to identify magnetic signatures possibly associated with mineralized hydrothermal alterations. These maps showed an ellipsoid-shaped low magnetic anomaly in the eastern porphyry center associated with phyllic alteration hosting Cu-Mo mineralization. These low magnetic anomalies can be used to identify zones of subsurface mineralization at Kahang deposit. Discussion In this research, remote sensing, geological, geochemical, and geophysical studies showed three porphyry centers at Kahang deposit. The world-class economic mineralization only occurred in the eastern porphyry center due to the presence of extensively strongly altered and brecciated quartz monzonite porphyry units showing low magnetic signatures and high Cu-Mo additive index anomalies. By comparing the low magnetic anomalies, high Cu-Mo anomalies, alteration zonation, brecciated rock units, and favorable structures, successful drilling targets can be identified to test subsurface mineralization at Kahang deposit. The integration of this information along with the geochemical and primary drilling information were used to plan systematic drilling. Most of the holes drilled in this zone at depths greater than 150 meters encountered economic mineralization of copper (approximately 0.5%) and molybdenum (approximately 700 ppm). The magmatic arc of Urmia-Dokhtar is considered the most important copper (molybdenum, gold) porphyry province in Iran. Most of the known large porphyry deposits of Iran, such as Sarcheshmeh and Meidok, are located in the southeast of this magmatic arc, and Songun is located in its northwest. In the central part of the Urmia Dokhtar magmatic arc, which is located in Isfahan and Central provinces, no similar deposit was reported prior to the discovery of Kahang deposit. Therefore, these studies have shown that the middle part of this arc may have the potential for many hidden porphyry mineralizations like Kahang deposit. Therefore, the exploration criteria identified in this study can be used for the exploration of similar deposits in this area at various stages of exploration, from identification to detailed exploration.

https://ijp.ui.ac.ir/article_28143_0430865660bcc0a1c81aa9822b5b27f4.pdf

University of Isfahan Petrological Journal 2228-5210 14 4 2024 02 20 Petrogenesis of Neogene subvolcanic rocks in Kamu, North of Isfahan Petrogenesis of Neogene subvolcanic rocks in Kamu, North of Isfahan 101 120 28380 10.22108/ijp.2024.140871.1325 FA Shahrzad Sherafat Assistant Professor, Department of Geology, Faculty of Sciences, Payame Noor University, Tehran, Iran, Mahnaz Khodami Assistant Professor, Department of Geology, Faculty of Sciences, Yazd University, Yazd, Iran, Journal Article 2024 03 03 Introduction Neogene igneous domes, formed by the Eurasian and Arabian subduction, exposed in the north of Kamu in the Urumia-Dokhtar magmatic arc. The study area is located 120 km north of Isfahan, between 31° 05° to 31° 10° north latitude and 51° 10° to 51° 20° east longitude. The purpose of the present paper is to investigate the tectonic setting, petrogenesis, and magmatic evolution processes involved in the formation of studied igneous rocks. Analytical methods After analyzing satellite images, maps and the previous studies, outcrops were selected for sampling. Following field studies, samples were collected and observed under a polarizing microscope as thin sections. 11 samples with the lowest amount of alteration were selected and analyzed by inductively coupled plasma spectrometry at ACME Canada laboratory. The article was written after analyzing and combining data from field studies, petrography, geochemistry, and chemical analyses results using GCDkit and CorelDRAW software. Petrography and Whole Rocks Chemistry The studied rocks are mainly dacite and andesite. Andesites are porphyritic with phenocrysts of plagioclase, amphibole, biotite and rarely pyroxene. Dacites have fine-grained or porphyry textures with aphanitic or trachytic groundmass and phenocrysts of plagioclase, quartz, amphibole and biotite. The mineralogy of dacites is similar to that of the andesitic rocks and are distinguished from andesites by the absence of pyroxene and the presence of quartz microcrystals. Sericite, kaolinite, chlorite, calcite, opaque and sphene as secondary minerals are obtained from the alteration of plagioclase, amphibole, biotite and pyroxene The SiO2 content varies from 61.58 to 68.64% wt. The amounts of Na2O and K2O range from 3.49-4.95% and 2.33-3.07%wt respectively. The rocks under study are classified as high potassium calc-alkaline and meta-aluminous dacite and andesite in the classification diagram. Discussion The multi-element pattern normalized to the primary mantle as well as to mid-ocean basalt show the enrichment of large ion lithophile elements (LILE) such as Ba, Sr, and Rb and the depletion of Ti, Nb, Ta, and P elements. These features are indicators of arc magmatism and are seen in magmas associated with the subducted crust and the mantle wedge. The chondrite normalized pattern shows a steep trend from light rare earth elements LREE to heavy rare earth elements HREE without a distinct anomaly of europium. The enrichment of LREE compared to HREE is due to low-grade partial melting or magmatic contamination with crustal materials. The lack of negative anomalies of europium, strontium, and barium indicates that the continental crust did not affect the melting process. Also, the lack of europium anomaly is usually attributed to the absence of plagioclase in the origin and its non-involvement in the melting process or the oxidant conditions of the origin. Additionally, the presence of garnet or amphibole in the origin is suggested by the small amounts of HREEs. The changes of REE in the normalized diagrams with chondrite and primary mantle can also be explained by the metasomatized mantle source. The rocks are classified into a magmatic arc and continental margin arc based on the ternary diagram of Nb/8, La/10, Y/15, the Ta/Hf versus Th/Hf, and also Zr versus Y diagrams. The magmatism of the subduction zones can be caused by the melting of the slab or mantle. In the Th/Yb versus Nb/Yb diagram which is used to detect the origin of magma, the samples also follow the trend of the volcanic arc array. The increase in thorium values and the positive slope of the graphs show the participation of the crustal contamination processes in the evolution of magma. The rocks have higher SiO2, Sr, Sr/Y, La/Yb and lower MgO, Yb, Y, and HREEs than normal calc-alkaline rocks. The studied samples show adakitic characteristics in the diagrams presented for the separation of adakitic rocks from common magmas of subduction zones. Adakitic magmas are produced from the partial melting of metamorphic basaltic compounds in the eclogite-amphibolite facies and slab in subduction zones. According to some researchers, the partial melting of the lower part of the thickened crust or the melting of the metasomatized mantle are other options for the production of adakitic magmas. The Rb versus K2O/Na2O and CaO/Al2O3 versus K2O/Na2O diagrams indicate that slab melting is more significant in magma formation than lower crust melting. The high values of Sr/Ce and Nb/Zr also indicate the role of the slab in magma production. The high and positive correlation of the Ba/Nb ratio versus niobium is a sign of the direct involvement of the slab in the source melt because in the process of subduction, Nb is less mobile and when Ba is removed into the mantle. However, the dispersion and negative correlation of the samples observed in the diagrams suggest that the melt was not formed directly from the slab and that the geochemical changes cannot be solely attributed to the differentiation of the oceanic crust. Due to the low values of MgO and Ni, it does not match with the mantle melts, but it is believed that this magma originated from the mantle, which was metasomatized with slab melts and fluids. Metasomatism of the mantle wedge with slab-derived fluids increases the amount of LILEs (K, Rb, Ba, Sr, Th, U) and decreases the amount of HFSEs (Nb, Ti, Ta). Geochemical diagrams show that melts from sediments along with slabs have played a more effective role in mantle deformation. Figure 10 represents magma derived from amphibolite origin. At depths greater than 45-50 km, garnet is stable while at depths less than 35 km, pyroxene is stable and at depths less than 30-45 km, amphibole is stable. As a result, magma can be generated from depths of about 45 km. Amphibolite is located in the mantle wedge and undergoes metasomatism through slab melts and fluids. Melting occurs at the depth of garnet stability originating from an amphibolite source. Introduction Neogene igneous domes, formed by the Eurasian and Arabian subduction, exposed in the north of Kamu in the Urumia-Dokhtar magmatic arc. The study area is located 120 km north of Isfahan, between 31° 05° to 31° 10° north latitude and 51° 10° to 51° 20° east longitude. The purpose of the present paper is to investigate the tectonic setting, petrogenesis, and magmatic evolution processes involved in the formation of studied igneous rocks. Analytical methods After analyzing satellite images, maps and the previous studies, outcrops were selected for sampling. Following field studies, samples were collected and observed under a polarizing microscope as thin sections. 11 samples with the lowest amount of alteration were selected and analyzed by inductively coupled plasma spectrometry at ACME Canada laboratory. The article was written after analyzing and combining data from field studies, petrography, geochemistry, and chemical analyses results using GCDkit and CorelDRAW software. Petrography and Whole Rocks Chemistry The studied rocks are mainly dacite and andesite. Andesites are porphyritic with phenocrysts of plagioclase, amphibole, biotite and rarely pyroxene. Dacites have fine-grained or porphyry textures with aphanitic or trachytic groundmass and phenocrysts of plagioclase, quartz, amphibole and biotite. The mineralogy of dacites is similar to that of the andesitic rocks and are distinguished from andesites by the absence of pyroxene and the presence of quartz microcrystals. Sericite, kaolinite, chlorite, calcite, opaque and sphene as secondary minerals are obtained from the alteration of plagioclase, amphibole, biotite and pyroxene The SiO2 content varies from 61.58 to 68.64% wt. The amounts of Na2O and K2O range from 3.49-4.95% and 2.33-3.07%wt respectively. The rocks under study are classified as high potassium calc-alkaline and meta-aluminous dacite and andesite in the classification diagram. Discussion The multi-element pattern normalized to the primary mantle as well as to mid-ocean basalt show the enrichment of large ion lithophile elements (LILE) such as Ba, Sr, and Rb and the depletion of Ti, Nb, Ta, and P elements. These features are indicators of arc magmatism and are seen in magmas associated with the subducted crust and the mantle wedge. The chondrite normalized pattern shows a steep trend from light rare earth elements LREE to heavy rare earth elements HREE without a distinct anomaly of europium. The enrichment of LREE compared to HREE is due to low-grade partial melting or magmatic contamination with crustal materials. The lack of negative anomalies of europium, strontium, and barium indicates that the continental crust did not affect the melting process. Also, the lack of europium anomaly is usually attributed to the absence of plagioclase in the origin and its non-involvement in the melting process or the oxidant conditions of the origin. Additionally, the presence of garnet or amphibole in the origin is suggested by the small amounts of HREEs. The changes of REE in the normalized diagrams with chondrite and primary mantle can also be explained by the metasomatized mantle source. The rocks are classified into a magmatic arc and continental margin arc based on the ternary diagram of Nb/8, La/10, Y/15, the Ta/Hf versus Th/Hf, and also Zr versus Y diagrams. The magmatism of the subduction zones can be caused by the melting of the slab or mantle. In the Th/Yb versus Nb/Yb diagram which is used to detect the origin of magma, the samples also follow the trend of the volcanic arc array. The increase in thorium values and the positive slope of the graphs show the participation of the crustal contamination processes in the evolution of magma. The rocks have higher SiO2, Sr, Sr/Y, La/Yb and lower MgO, Yb, Y, and HREEs than normal calc-alkaline rocks. The studied samples show adakitic characteristics in the diagrams presented for the separation of adakitic rocks from common magmas of subduction zones. Adakitic magmas are produced from the partial melting of metamorphic basaltic compounds in the eclogite-amphibolite facies and slab in subduction zones. According to some researchers, the partial melting of the lower part of the thickened crust or the melting of the metasomatized mantle are other options for the production of adakitic magmas. The Rb versus K2O/Na2O and CaO/Al2O3 versus K2O/Na2O diagrams indicate that slab melting is more significant in magma formation than lower crust melting. The high values of Sr/Ce and Nb/Zr also indicate the role of the slab in magma production. The high and positive correlation of the Ba/Nb ratio versus niobium is a sign of the direct involvement of the slab in the source melt because in the process of subduction, Nb is less mobile and when Ba is removed into the mantle. However, the dispersion and negative correlation of the samples observed in the diagrams suggest that the melt was not formed directly from the slab and that the geochemical changes cannot be solely attributed to the differentiation of the oceanic crust. Due to the low values of MgO and Ni, it does not match with the mantle melts, but it is believed that this magma originated from the mantle, which was metasomatized with slab melts and fluids. Metasomatism of the mantle wedge with slab-derived fluids increases the amount of LILEs (K, Rb, Ba, Sr, Th, U) and decreases the amount of HFSEs (Nb, Ti, Ta). Geochemical diagrams show that melts from sediments along with slabs have played a more effective role in mantle deformation. Figure 10 represents magma derived from amphibolite origin. At depths greater than 45-50 km, garnet is stable while at depths less than 35 km, pyroxene is stable and at depths less than 30-45 km, amphibole is stable. As a result, magma can be generated from depths of about 45 km. Amphibolite is located in the mantle wedge and undergoes metasomatism through slab melts and fluids. Melting occurs at the depth of garnet stability originating from an amphibolite source.

https://ijp.ui.ac.ir/article_28380_bf55c60244f76e491e5ae035da46411b.pdf

University of Isfahan Petrological Journal 2228-5210 14 4 2024 02 20 An overview of the formation stages of Porphyry-Epithermal Negar copper deposit, southwest of Kerman: Based on geological, petrological, and geochemical studies of Negar area An overview of the formation stages of Porphyry-Epithermal Negar copper deposit, southwest of Kerman: Based on geological, petrological, and geochemical studies of Negar area 121 146 28408 10.22108/ijp.2024.141008.1328 FA Soudeh Sedighian Assistant Professor, Department of Geology, Faculty of Technical Engineering and Basic Sciences, Velayat University, Iranshahr, Iran, Bahram Bahrambeygi Assistant Professor, Camborne School of Mine (CSM), University of Exeter, England, Hesam Moeinzadeh Professor, Department of Geology, Shahid Bahonar University, Kerman, Iran, Journal Article 2024 03 19 The Negar copper zone with about 1.2 Km2 is located in the southern part of the Urumieh-Dokhtar Magmatic Belt. The Dehaj- Sarduiyeh metallogenic belt is considered as a part of the Central Iranian volcanic belt. The history of the formation of this volcanic belt, which resulted from the subduction of the Neotethys ocean under the Central Iranian microcontinent (Alavi, 1991), has been influential in the potential of this deposit and similar deposits. The Negar area has not been precisely studied so far; therefore, in this research, efforts have been made to achieve a more detail and comprehensive understanding of ore mineralization and ore formation in this studied area based on geological, alteration, and geochemical studies. Regional Geology The southeastern part of the Urumieh-Dokhtar belt is known as the Dehaj- Sarduiyeh metallogenic zone or the Cenozoic magmatic arc of Kerman. In fact, the Oligo-Miocene-Pliocene intrusives in this belt have penetrated into Eocene volcanic units and, with the expansion of alteration zones, gave rise to extensive mineralization in the region. The largest porphyry deposits from the Kerman magmatic belt are associated with two types of Oligocene-Miocene granitoid rocks, Kuh-Panj and Jebal-Barez (Mohammadzadeh et al., 2018). Among them, the largest porphyry copper mineralizations are associated with Kuh-Panj granitoids, which are mostly concentrated in the northern and central parts of this belt. Two important volcanic units present in this belt include the Razak and Hazar volcanic complexes. The Razak complex consists of a sequence of volcanic rocks and sediments (Nedimovic, 1973). These strongly folded volcanic and pyroclastic rocks intruded by granitoid intrusive masses (Oligocene-Miocene). The injection of these masses occurred along the major faults and axes of the anticlines in the region, leading to mineralization in the form of porphyry, vein, and regional veins in the area as well. Analytical Methods In order to conduct geochemical studies, more than 30 samples from drilling logs, 9 samples from oxidized veins containing malachite mineralization, and approximately 40 samples from breccias, host rocks, alterations, and surface volcanic rocks were collected in trenches and outcrops. A total of 83 samples were collected using the Rock Chip method from the limited area to analysis by ICP-Mass method to the Iran Mineral Processing Research Center in Karaj. Discussion Mineralogical studies and investigations show that in the polished sections of the rocks in the studied area, metallic minerals such as hematite, goethite, pyrite, chalcopyrite, chalcocite, and possibly gold are often observable. The predominant texture is scattered grain texture, vein-like, and filling empty spaces. The sulfide minerals are scattered throughout the background of rock samples. As the field investigation display alteration and mineralization zones ae intimate association showing a specific pattern with propylitic alteration in the surroundings, phyllic and argillic zones in the center of the hydrothermal system, whereas silicic alteration with minor alonitization occupied the ore-bearing zone with abundant fracturing and veins, High levels of copper and mineralization in the inner parts of the hydrothermal system occurred in relation to alterations and the occurrence of boiling phenomena. The bimodal distribution diagram of copper also clearly indicates the abnormality of the entire area and the multiple ore-forming phases in this mineralized zone. Probability in the initial stage of the formation of this deposit, deep granitoid masses intruded the upper volcanic rocks and sedimentary sequences in the region. The differentiation of intrusive masses and the accumulation of hydrothermal fluids and mostly magmatic solutions containing various chalcophile elements in their upper levels led to an increase in vapor pressure of fluids and consequently the movement of these solutions along the weak points such as major faults. As the temperature of these solutions reduces their acidic nature changes giving rise to precipitation the primary elements including Cu., the temperature of the rocks along the path of the hydrothermal solutions increases. as the passage of hydrothermal solutions continues, thus, hot acidic solutions, produce a high concentration of elements and to deposit these elements as the sulfide veins and advanced argillic alterations. Conclusion Negar area in the south (or southwest?) of Kerman province indicate the high potential for copper mineralization. According to field and geological evidences, mineralization in this area occurred in volcanic rocks and its pyroclastic materials, and the intrusive bodies played a significant role in the development processes. Due to the mineralization area, its formation processes are directly related to subduction of the Neotethys ocean during the Cenozoic era, particularly the Eocene time. The extensional forces resulting from this subduction as well as the movement of faults create fractures and void spaces providing suitable pathways for migration of magma and associated ore-forming fluids. In the Negar copper deposit area, two types of significant copper ore reserves are present. One type is the epithermal surface copper ore reserves located in the eastern parts, and the other type is the deep porphyry copper ore reserves found in the western part of the area. The overall geological, mineralogical and the geochemical features document that the Negar copper deposit is an epithermal deposit with high sulfidation type. The Negar copper zone with about 1.2 Km2 is located in the southern part of the Urumieh-Dokhtar Magmatic Belt. The Dehaj- Sarduiyeh metallogenic belt is considered as a part of the Central Iranian volcanic belt. The history of the formation of this volcanic belt, which resulted from the subduction of the Neotethys ocean under the Central Iranian microcontinent (Alavi, 1991), has been influential in the potential of this deposit and similar deposits. The Negar area has not been precisely studied so far; therefore, in this research, efforts have been made to achieve a more detail and comprehensive understanding of ore mineralization and ore formation in this studied area based on geological, alteration, and geochemical studies. Regional Geology The southeastern part of the Urumieh-Dokhtar belt is known as the Dehaj- Sarduiyeh metallogenic zone or the Cenozoic magmatic arc of Kerman. In fact, the Oligo-Miocene-Pliocene intrusives in this belt have penetrated into Eocene volcanic units and, with the expansion of alteration zones, gave rise to extensive mineralization in the region. The largest porphyry deposits from the Kerman magmatic belt are associated with two types of Oligocene-Miocene granitoid rocks, Kuh-Panj and Jebal-Barez (Mohammadzadeh et al., 2018). Among them, the largest porphyry copper mineralizations are associated with Kuh-Panj granitoids, which are mostly concentrated in the northern and central parts of this belt. Two important volcanic units present in this belt include the Razak and Hazar volcanic complexes. The Razak complex consists of a sequence of volcanic rocks and sediments (Nedimovic, 1973). These strongly folded volcanic and pyroclastic rocks intruded by granitoid intrusive masses (Oligocene-Miocene). The injection of these masses occurred along the major faults and axes of the anticlines in the region, leading to mineralization in the form of porphyry, vein, and regional veins in the area as well. Analytical Methods In order to conduct geochemical studies, more than 30 samples from drilling logs, 9 samples from oxidized veins containing malachite mineralization, and approximately 40 samples from breccias, host rocks, alterations, and surface volcanic rocks were collected in trenches and outcrops. A total of 83 samples were collected using the Rock Chip method from the limited area to analysis by ICP-Mass method to the Iran Mineral Processing Research Center in Karaj. Discussion Mineralogical studies and investigations show that in the polished sections of the rocks in the studied area, metallic minerals such as hematite, goethite, pyrite, chalcopyrite, chalcocite, and possibly gold are often observable. The predominant texture is scattered grain texture, vein-like, and filling empty spaces. The sulfide minerals are scattered throughout the background of rock samples. As the field investigation display alteration and mineralization zones ae intimate association showing a specific pattern with propylitic alteration in the surroundings, phyllic and argillic zones in the center of the hydrothermal system, whereas silicic alteration with minor alonitization occupied the ore-bearing zone with abundant fracturing and veins, High levels of copper and mineralization in the inner parts of the hydrothermal system occurred in relation to alterations and the occurrence of boiling phenomena. The bimodal distribution diagram of copper also clearly indicates the abnormality of the entire area and the multiple ore-forming phases in this mineralized zone. Probability in the initial stage of the formation of this deposit, deep granitoid masses intruded the upper volcanic rocks and sedimentary sequences in the region. The differentiation of intrusive masses and the accumulation of hydrothermal fluids and mostly magmatic solutions containing various chalcophile elements in their upper levels led to an increase in vapor pressure of fluids and consequently the movement of these solutions along the weak points such as major faults. As the temperature of these solutions reduces their acidic nature changes giving rise to precipitation the primary elements including Cu., the temperature of the rocks along the path of the hydrothermal solutions increases. as the passage of hydrothermal solutions continues, thus, hot acidic solutions, produce a high concentration of elements and to deposit these elements as the sulfide veins and advanced argillic alterations. Conclusion Negar area in the south (or southwest?) of Kerman province indicate the high potential for copper mineralization. According to field and geological evidences, mineralization in this area occurred in volcanic rocks and its pyroclastic materials, and the intrusive bodies played a significant role in the development processes. Due to the mineralization area, its formation processes are directly related to subduction of the Neotethys ocean during the Cenozoic era, particularly the Eocene time. The extensional forces resulting from this subduction as well as the movement of faults create fractures and void spaces providing suitable pathways for migration of magma and associated ore-forming fluids. In the Negar copper deposit area, two types of significant copper ore reserves are present. One type is the epithermal surface copper ore reserves located in the eastern parts, and the other type is the deep porphyry copper ore reserves found in the western part of the area. The overall geological, mineralogical and the geochemical features document that the Negar copper deposit is an epithermal deposit with high sulfidation type.

https://ijp.ui.ac.ir/article_28408_8258dc4306d9d0100039d59100fb554e.pdf

University of Isfahan Petrological Journal 2228-5210 14 4 2024 02 20 Petrography, geochemistry, mineralogy and type of Cu (Ag) mineralization study of Rahimabad ore deposit, southwest of Ardestan Petrography, geochemistry, mineralogy and type of Cu (Ag) mineralization study of Rahimabad ore deposit, southwest of Ardestan 147 176 28375 10.22108/ijp.2024.140522.1319 FA Mehrdad Barati Assistant Professor, Department of Geology, University of Bu Ali Sina, Hamedan, Iran, Akram Ostadhosseini Ph.D, Ministry of Industry, Mine and Trade, Scientific Research Institute of Copper Gold Ardestan, Esfahan, Iran, Peyman Afzal Professor, Department of Petroleum and Mining Engineering, South Tehran branch, Islamic Azad University, Tehran, Iran, Insung Lee Professor, School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea. Journal Article 2024 01 24 The study area is situated 21 km SW of Ardestan city and 80 km NE of Esfahan (Central Iran). and according to the sedimentary structural divisions (Fig. 1; Aghanabati, 1998) in the central part of Urumieh-Dokhtar Magmatic Belt (UDMB) The UDMB in the Alpine-Himalayan orogenic belt, the most productive metallic belt of Iran, composed of basic to acidic volcanic and plutonic rocks, tuff and agglomerate. The UDMB represents geochemical characteristics of subduction zones with features of calc-alkaline locally toward alkaline (Berberian and Berberian, 1981; Alavi, 1994; Shahabpour, 2007; Omrani et al., 2008; Ghorbani and Bezenjani, 2011; Yeganehfar, 2013; Rajabpour et al., 2017). The UDMB hosts several porphyry Cu±Mo±Au deposits including Sungun, Sarcheshmeh, Kahang, Darehzar, Nowchun and Meiduk (Atapour and Aftabi, 2007; Zarasvandi et al., 2015; Zamanian et al., 2016; Alirezaei et al., 2017; Jamali, 2017) and associated porphyry copper-gold, gold epithermal and manganese-iron deposits (Rajabpour et al., 2017; Ostadhosseini et al., 2018; Alaminia et al., 2020; Ostadhosseini et al., 2021). Different stages of Cenozoic magmatic activity in the middle segment of the UDMB around the study area consist of different successions of volcanic and intrusive rocks (Radfar, 1998). The Eocene to Miocene diorite- monzodiorite bodies were intruded the Eocene volcanic and subvolcanic rocks. In the middle of the area, these intrusive units are juxtaposed with a fault boundary (Marbin fault) adjacent to Eocene volcanic units. The Eocene volcanic stage is dominated by basalt, andesitic basalt, andesite, tuffs and ignimbrites rocks. Quaternary sediments are widespread in the northeastern and southern parts of the area. The oldest rock unit of this area is the Shotori dolomite formation trending NW-SW and belonging to Triassic age and located in the southwest of the study area. Cu mineralization occurs within the Eocene volcano-sedimentary sequence. The purpose of this study is to determine the type of Cu mineralization based on the mineralization characteristics, geometry, texture, structure and alteration studies, as well as the geochemistry and tectonic environment of the host volcanic rock. Materials and Methods For the purposes of this study, 60 thin sections of volcanic rocks and 30 polished thin sections of ore samples were studied by a standard petrographic microscope under reflected and transmitted lights. 10 surface and drill–holes samples from volcanic rocks were crushed and powdered in tungsten carbide swing mill for whole-rock analysis. The chemical analyses were performed for the major elements using X-ray fluorescence (XRF) and trace elements using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Electron microprobe analyses were performed, using a JXA-8100 electron microprobe. Operating conditions were 35 kV accelerating voltage, a beam current of 20 nA, and a beam diameter of 2-10 μm. All the petrographic studies as well as chemical analyses including XRF, ICP-MS and EPMA were carried out at the Seoul National University Laboratories, Seoul, South Korean. Results and Discussion The dominant rocks of the area under study are basalt, basaltic andesite, andesite and a small volume of pyroclastic rocks which are metaluminous composition and calc-alkaline affinity. Geochemically, they are enriched in LREE relative to HREE, enrichment of LILE and negative anomalies of HFSE (i.e., Nb, Ti), pointing to characteristics of subduction-related magmatic possibly generated by partial melting of metasomatized lithospheric mantle source. As the discrimination diagrams of tectonic setting display, the volcanic rocks are also classified as a subduction-related magmatic arc. Alteration zones were developed in the rock types including silicic, propylitic, argillic, sericitic and zeolitic. The propylitic and silicic alterations were extended within the mineralized zones. The propylitic alteration is the dominant alteration consisting mainly epidote, chlorite, and calcite. The silicification zone consists of crystalline quartz-formation, which occurs as veins and veinlets including some copper minerals. The carbonate alteration is observed in basaltic andesite and andesite rocks. Copper mineralization is mainly strata-bound, and occurs partially as veins, veinlets and disseminated in the andesite, basaltic andesites, and basaltic rocks. Based on microscopic studies, three mineralization stages were recognized in the Rahimabad deposit including pre-mineralization, mineralization, and post-mineralization stages. In the pre-mineralization stage, pyrite is formed in decreasing conditions in the host rock. In the main mineralization stage, pyrite is replaced by primary Cu and Ag sulfide minerals such as chalcopyrite, bornite, chalcocite, digenite, jalpaite and acanthite. Finally, in the post mineralization stage, copper sulfide minerals are replaced by secondary copper sulfide minerals (chalcocite, covellite and digenite) and oxide minerals (malachite, azurite, goethite and hematite). Conclusions The Rahimabad Cu (Ag) deposit lies in the SW of the Ardestan city in the Urumieh-Dokhtar Magmatic Belts, Central Iran. In this area, Cu and Ag mineralization is observed in the volcano-sedimentary rocks. The copper (Ag) mineralization occurs in andesite, basaltic andesite and basaltic lavas. These rocks are meta-aluminous and have a calc-alkaline affinity and indicate a subduction-related magmatic arc. The main alterations zones are silicic, propylitic, argillic, sericitic and zeolitic. The geometry of mineralization is strata-bound and the texture and structure of mineralization is open space filling, disseminated, vein-veinlet and replacement. Based on microscopic as well as EPMA data, the most important Cu and Ag minerals include chalcopyrite, bornite, chalcocite- covellite group minerals, malachite, azurite, acanthite and jalpaite, which are accompanied by magnetite and hematite. Pyrite is mostly observed as a separate mineral in the host rock. The overall mineralization characteristics and tectonic setting, the type of host rock, geometry, texture and structure, mineralogy and the paragenetic of Cu minerals and finally the alteration zones with different types of copper deposits document that the Rahimabad copper deposit share many features with those of Manto type copper deposits. Acknowledgment The present study was financially supported by the Cu-Au company of Ardestan. The authors are grateful to Mr. Sharif for providing sampling facilities and let us access to drill cores and exploration data. The study area is situated 21 km SW of Ardestan city and 80 km NE of Esfahan (Central Iran). and according to the sedimentary structural divisions (Fig. 1; Aghanabati, 1998) in the central part of Urumieh-Dokhtar Magmatic Belt (UDMB) The UDMB in the Alpine-Himalayan orogenic belt, the most productive metallic belt of Iran, composed of basic to acidic volcanic and plutonic rocks, tuff and agglomerate. The UDMB represents geochemical characteristics of subduction zones with features of calc-alkaline locally toward alkaline (Berberian and Berberian, 1981; Alavi, 1994; Shahabpour, 2007; Omrani et al., 2008; Ghorbani and Bezenjani, 2011; Yeganehfar, 2013; Rajabpour et al., 2017). The UDMB hosts several porphyry Cu±Mo±Au deposits including Sungun, Sarcheshmeh, Kahang, Darehzar, Nowchun and Meiduk (Atapour and Aftabi, 2007; Zarasvandi et al., 2015; Zamanian et al., 2016; Alirezaei et al., 2017; Jamali, 2017) and associated porphyry copper-gold, gold epithermal and manganese-iron deposits (Rajabpour et al., 2017; Ostadhosseini et al., 2018; Alaminia et al., 2020; Ostadhosseini et al., 2021). Different stages of Cenozoic magmatic activity in the middle segment of the UDMB around the study area consist of different successions of volcanic and intrusive rocks (Radfar, 1998). The Eocene to Miocene diorite- monzodiorite bodies were intruded the Eocene volcanic and subvolcanic rocks. In the middle of the area, these intrusive units are juxtaposed with a fault boundary (Marbin fault) adjacent to Eocene volcanic units. The Eocene volcanic stage is dominated by basalt, andesitic basalt, andesite, tuffs and ignimbrites rocks. Quaternary sediments are widespread in the northeastern and southern parts of the area. The oldest rock unit of this area is the Shotori dolomite formation trending NW-SW and belonging to Triassic age and located in the southwest of the study area. Cu mineralization occurs within the Eocene volcano-sedimentary sequence. The purpose of this study is to determine the type of Cu mineralization based on the mineralization characteristics, geometry, texture, structure and alteration studies, as well as the geochemistry and tectonic environment of the host volcanic rock. Materials and Methods For the purposes of this study, 60 thin sections of volcanic rocks and 30 polished thin sections of ore samples were studied by a standard petrographic microscope under reflected and transmitted lights. 10 surface and drill–holes samples from volcanic rocks were crushed and powdered in tungsten carbide swing mill for whole-rock analysis. The chemical analyses were performed for the major elements using X-ray fluorescence (XRF) and trace elements using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Electron microprobe analyses were performed, using a JXA-8100 electron microprobe. Operating conditions were 35 kV accelerating voltage, a beam current of 20 nA, and a beam diameter of 2-10 μm. All the petrographic studies as well as chemical analyses including XRF, ICP-MS and EPMA were carried out at the Seoul National University Laboratories, Seoul, South Korean. Results and Discussion The dominant rocks of the area under study are basalt, basaltic andesite, andesite and a small volume of pyroclastic rocks which are metaluminous composition and calc-alkaline affinity. Geochemically, they are enriched in LREE relative to HREE, enrichment of LILE and negative anomalies of HFSE (i.e., Nb, Ti), pointing to characteristics of subduction-related magmatic possibly generated by partial melting of metasomatized lithospheric mantle source. As the discrimination diagrams of tectonic setting display, the volcanic rocks are also classified as a subduction-related magmatic arc. Alteration zones were developed in the rock types including silicic, propylitic, argillic, sericitic and zeolitic. The propylitic and silicic alterations were extended within the mineralized zones. The propylitic alteration is the dominant alteration consisting mainly epidote, chlorite, and calcite. The silicification zone consists of crystalline quartz-formation, which occurs as veins and veinlets including some copper minerals. The carbonate alteration is observed in basaltic andesite and andesite rocks. Copper mineralization is mainly strata-bound, and occurs partially as veins, veinlets and disseminated in the andesite, basaltic andesites, and basaltic rocks. Based on microscopic studies, three mineralization stages were recognized in the Rahimabad deposit including pre-mineralization, mineralization, and post-mineralization stages. In the pre-mineralization stage, pyrite is formed in decreasing conditions in the host rock. In the main mineralization stage, pyrite is replaced by primary Cu and Ag sulfide minerals such as chalcopyrite, bornite, chalcocite, digenite, jalpaite and acanthite. Finally, in the post mineralization stage, copper sulfide minerals are replaced by secondary copper sulfide minerals (chalcocite, covellite and digenite) and oxide minerals (malachite, azurite, goethite and hematite). Conclusions The Rahimabad Cu (Ag) deposit lies in the SW of the Ardestan city in the Urumieh-Dokhtar Magmatic Belts, Central Iran. In this area, Cu and Ag mineralization is observed in the volcano-sedimentary rocks. The copper (Ag) mineralization occurs in andesite, basaltic andesite and basaltic lavas. These rocks are meta-aluminous and have a calc-alkaline affinity and indicate a subduction-related magmatic arc. The main alterations zones are silicic, propylitic, argillic, sericitic and zeolitic. The geometry of mineralization is strata-bound and the texture and structure of mineralization is open space filling, disseminated, vein-veinlet and replacement. Based on microscopic as well as EPMA data, the most important Cu and Ag minerals include chalcopyrite, bornite, chalcocite- covellite group minerals, malachite, azurite, acanthite and jalpaite, which are accompanied by magnetite and hematite. Pyrite is mostly observed as a separate mineral in the host rock. The overall mineralization characteristics and tectonic setting, the type of host rock, geometry, texture and structure, mineralogy and the paragenetic of Cu minerals and finally the alteration zones with different types of copper deposits document that the Rahimabad copper deposit share many features with those of Manto type copper deposits. Acknowledgment The present study was financially supported by the Cu-Au company of Ardestan. The authors are grateful to Mr. Sharif for providing sampling facilities and let us access to drill cores and exploration data.

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