https://ijp.ui.ac.ir/ Petrological Journal en daily 1 Sat, 07 Feb 2026 00:00:00 +0330 Sat, 07 Feb 2026 00:00:00 +0330 https://ijp.ui.ac.ir/article_30272.html https://ijp.ui.ac.ir/article_29961.html IntroductionThe Chah Gonbad area is located 125 km southwest of Birjand, 90 km southwest of Khousf, and about 40 km southwest of Khour village, between the longitudes 58º07ʹ30ʺ–58º14ʹ50ʺ and the latitudes 32º36ʹ23ʺ–32º42ʹ40ʺ. Based on the 1:100, 000 map of Seh Changi prepared by Eftekharnejad and Stöcklin (1975), the studied area is located in the northeast of Sechangi, north of the Lut Block. Access to the area is possible via the main Birjand–Khousf–Khour–Kerman road and the Khour–Chah Gonbad–Sechangi side road (Figure 1). There are various opinions about the formation of the volcanic rocks of the Lut Block (Eftekharnejad, 1972; Darvishzadeh, 1976; Jung et al., 1983; Camp and Griffis, 1982; Tirrul et al., 1983; Tarkian et al., 1983; Pang et al., 2013; Omidianfar, et al., 2018; Kalatbari Jafari et al., 2019, 2020, 2021; Fotoohi Rad et al., 2022; Yousefzadeh and Chahkandinezhad, 2023). The studied rocks range from basic/intermediate to acidic compositions. The main purpose of this research is therefore to provide detailed petrological and geochemical information on volcanic rocks in the Chah Gonbad area to constrain the tectonic setting of these rocks and to identify the geology of the Lut Block in eastern Iran.Regional GeologyThe Tertiary volcanic rocks are extensively exposed in the north of Chah Gonbad. These volcanic and pyroclastic rocks, which cover most of the region, include tuff, perlite, and ignimbrite (Paleogene), as well as rhyolite, dacite (associated pyroclastics), and andesite/ basaltic andesite (Neogene) (Figure 2).Research Method In order to carry out this research, reports, geological and topographic maps, satellite images of the region, and references related to the research topic were first prepared and reviewed. In the next step, during 8 days of fieldwork, rock sampling was carried out by examining their field relationships. In the third step, 79 thin sections were prepared, and their mineralogical and textural descriptions were identified using a polarizing Leitz microscope. Then, 10 samples with the least alteration were selected and sent to Acme Canada Laboratory for analysis of major elements by the ICP-ES method and analysis of trace elements by the ICP-MS method. GCDKit, Excel (@2007), Grapher, and ArcGIS software were used to draw the diagrams and geological map. To calculate the amounts of Fe₂O₃ and FeO, Minpet software was used following the method of Irvine and Baragar (1971).PetrographyThe Chah Gonbad area has extensive outcrops of volcanic rocks with basic/intermediate to acidic compositions. The studied rocks range from basaltic andesite to rhyolitic compositions (basaltic andesite/andesite, rhyolite, dacite, perlite, and ignimbrite), with a peak in acidic compositions. These rocks are dominated by porphyritic texture with microlitic groundmass, glomeroporphyritic, hyaloporphyritic, poikilitic, perlitic, and spherolitic textures. Plagioclase (oligoclase–andesine), sanidine, pyroxene, hornblende, biotite, and quartz are common minerals. Evidence of disequilibrium, including sieve texture, chemical zoning and resorption margins in plagioclase, opacified margins in hornblende, and rounded or embayed edges in quartz and sanidine, are observed in these rocks.Geochemistry and PetrogenesisBased on various diagrams, the samples from Chah Gonbad fall within the range of andesite/basalt, andesite, trachyandesite, dacite, trachydacite, and rhyolite. These rocks have calc-alkaline, high-potassium calc-alkaline, and shoshonitic affinities (Figure 9C). In the Co versus Th diagram (Hastie et al., 2007), which is used for volcanic rocks, the samples show consistent trends. The Sun and McDonough diagram (1989) was used to normalize trace elements to the primitive mantle (Figure 10A). The overall geochemical characteristics, including depletion in Ba, Nb, P, Ti, and Ta, enrichment in LILEs (i.e., Cs, Th, U, K, Rb) relative to HFSEs (i.e., Nb, P, Zr, Ti, Ta), negative anomalies of Nb, Ti, and Ta, and high LILE/HREE ratios in the studied rocks, are features associated with subduction zone magmas. The observed negative Nb anomaly in these samples is an indicator of continental rocks and may suggest crustal participation in magmatic processes (Rollinson, 1993). Depletion of HFSEs such as Nb, P, Ta, and Ti is a prominent feature of arc environments and may result from magma derived from subducted oceanic crust and the overlying mantle wedge, which underwent fractional crystallization, assimilation, and contamination with crustal materials (Saunders et al., 1992; Nagudi et al., 2003). To study the behavior of rare earth elements in samples from the region, a normalized spider diagram with chondrites was used (Boynton, 1984) (Figure 10B). In this diagram, LREEs show enrichment relative to HREEs. According to Winter (2010), the enrichment in LREEs indicates formation in subduction zones. The low Eu depletion in these rocks could be due to high oxygen fugacity during formation and crystallization. Based on Nb versus Zr, Ta/Yb versus Th/Yb, and Yb versus Th/Ta ratios (Figures 11A-11E), the studied rocks are located in a subduction–post -collision setting and in the active continental margin. Geochemical characteristics and tectonic discrimination diagrams suggest that these volcanic rocks presumably formed in an immature continental arc setting (Figure 12). Considering the geological setting and petrological and geochemical evidence, it can be concluded that these rocks were formed in a post-collisional zone during delamination of the continental lithosphere in the Lut Block.ConclusionThe depletion of Ti, Nb, and Ta in the rocks of the region, along with low HREE and high LREE contents, indicates magmatism in a subduction zone. These rocks belong to the active continental margin. Depletion in Ti, Nb, and Ta (TNT) and Ba enrichment in Cs, Th, U, and Rb provide evidence of the role of continental crust in magmatic processes. Low amounts of Ni (>20) and Co (0.6–24.8), Mg# values less than 40 (12–40), and Nb/Ta ratios greater than 1 (8.9–23.5) indicate the prominent role of the crust in the formation or evolution of the parent magma. Based on geochemical evidence, the volcanic rocks of the Chah Gonbad region were formed in a post-collisional zone during thinning of the continental lithosphere in the Lut Block and in an immature continental margin arc. https://ijp.ui.ac.ir/article_29831.html IntroductionGeographically, the granitoid intrusion under investigation is located in Ardestan, in the northeastern part of Isfahan Province and to the north of the Nain ophiolitic complex, between longitudes 52°50′ to 53°03′ E and latitudes 33°09′N to 33°13′N. With a general northwest–southeast trend, this body is considered part of the Urumieh–Dokhtar magmatic arc. Previous studies conducted in or around the area include: Akbari (1999) conducted a petrographic and petrological study of the Sohail Pakouh and Golshaknan intrusive bodies and, based on the regional lithology, classified the intrusion as an I-type granite. Yeganehfar (2007) investigated the petrogenesis of the Tertiary rocks south of Ardestan and argued that these volcanic rocks display the characteristics of island-arc magmatism, exhibiting indications of evolution toward an active continental margin setting Rahmani (2018), studied the petrology, geochemistry, and tectonomagmatic setting of the Qah Sareh granitoids located in southeastern Ardestan. Babazadeh (2017), who also worked on the petrogenesis of the Tertiary rocks south of Ardestan. In this study, the similarities in major and trace elements as well as Sr–Nd isotopic characteristics of the plutonic and volcanic rocks of Ardestan indicate derivation from a common magma source. The author proposed a subduction model involving the Neo-Tethyan slab beneath the Central Iran mantle.Tourmaline has proven to be a highly useful mineral for petrological studies (Manning, 1982; London, 1999) due to its ability to crystallize under diverse pressure-temperature regimes and geological environments, and its stability across a wide range of metamorphic conditions and weathering. Given the lack of detailed geochemical investigation on the tourmalines of this area, this study aims to conduct petrographic analysis, determine the chemical composition, and elucidate the origin and formation conditions of the tourmalines present in the regional granitoids.Regional GeologyThe studied intrusive body lies within the western segment of the Central Iranian Zone and the central part of the Urumieh–Dokhtar magmatic arc, trending NW–SE (Fig. 1). Based on geographical distribution, it can be divided into the Sohil Pakouh, Goleshkanan, and Hajiabad subareas. These intrusive bodies, as part of the Urumieh–Dokhtar magmatic belt, have intruded into Eocene volcanic and volcaniclastic rocks in the northwestern part of the Nain ophiolite zone. Their emplacement has been dated to the Oligocene–Miocene (Amidi, 1975). The thermal impact of these intrusions has caused low- to very low-grade contact metamorphism in the host rocks.Analytical MethodsAfter sampling the granitoid rocks, 25 thin sections were prepared for mineralogical and textural analysis using an Olympus BH2 polarizing microscope. Following petrographic investigations, selected tourmaline grains were analyzed by electron microprobe at the University of Oklahoma, USA, to determine their elemental compositionPetrographyThe studied intrusions mainly consist of granodiorite, tonalite, diorite, and monzodiorite, appearing both as veins and dikes, as well as larger plutonic bodies. Dominant minerals include quartz, plagioclase, alkali feldspar, amphibole, biotite, and tourmaline. The average crystal size ranges from 4 to 9 mm. The rocks exhibit a granular texture, with subordinate poikilitic, perthitic, and granophyric textures. Late-stage intrusive activity after the Eocene led to thermal alteration of the regional Eocene volcanic rocks, forming siliceous–argillic breccias with white, yellow, to pink coloration. Petrographic evidence of metasomatism includes late-stage feldspar veinlets within quartz grains, brecciated textures in quartz, and partial replacement of plagioclase by potassium feldspar at grain margins. Electron microprobe analysis of adularia confirms the composition of the potassium feldspar. Adularia appears to have formed at the final crystallization stage of the granitoid as vein fillings, indicating pervasive potassium metasomatism driven by hydrothermal fluids.DiscussionThe rocks are primarily granodioritic, with occurrences of diorite, monzodiorite, and tonalite. The igneous rocks in southeastern Ardestan are mainly calc-alkaline in character, with metaluminous to peraluminous compositions, and are geochemically consistent with subduction-related tectonic settings. The chemical composition of tourmaline provides valuable insights into the physicochemical conditions of the host rock’s formation (Manning, 1982; Henry and Guidotti, 1985; London, 1999). To determine the structural formulae of the tourmalines, multiple grains from the granitoid samples were analyzed via electron microprobe. The calculated formulae are presented in Table 1. Analyses were conducted from the rim to the core of the tourmaline grains. The core and rim compositions are as follows:Core composition: (Na, K) 0.72 (Fe²⁺, Mn, Ti) 2.84 Mg1.5 Al4.85 B3 Si6 O27 (OH, F)4Rim composition: (Na, K)0.72 (Fe²⁺, Mn, Ti) 1.63 Mg1.73 Al5.7 B3 Si6 O27 (OH, F)4The tourmalines are thus members of the schorl–dravite solid solution series. Based on substitutions at the X site, tourmalines are classified into calcic, alkali, and X-site-vacant types depending on the relative proportions of Na+(K), Ca, and site vacancies (Hawthorne and Henry, 1999). According to this classification and as shown in Figure 7, most of the analyzed tourmalines fall within the alkali group, indicating high K and Na contents relative to Ca and minimal X-site vacancies. Alkali tourmalines typically form under acidic and lower-temperature conditions (Collins, 2010). In the Fe vs. Mg diagram, all samples plot above the ∑(Fe+Mg) = 3 line within the schorl–dravite field, indicating a deficiency of Al in the Z-site and its absence from the Y-site. The R1+R2 vs. R3 diagram [(Ca+Na)+(Fe+Mg+Mn) vs. Al+1.33Ti] of Manning (1982) (Fig. 11) reveals Al-involved substitutions, suggesting the presence of aluminous tourmaline, foitite, X-site vacancies, and olenite. In this diagram, the samples trend from the schorl–dravite composition toward uvite, indicating substitutions involving Ca, Mg, and Fe [(Ca (Fe, Mg) ↔ NaAl)].Based on the Fe–Mg–Ca ternary diagram (Henry and Guidotti, 1985), which is used to infer the nature of the fluids involved in tourmaline crystallization, most samples plot within the field of low-Ca metapelites and meta psammites and quartz-tourmaline rocks, while a few are positioned within the compositional field of lithium-deficient granitoids. (Fig. 12). In diagram 13, the tourmalines lie within fields B to C, indicating crystallization from environments ranging from proximal to intermediate, and even distal relative to the granitoid body. The FeO/(FeO + MgO) ratio is a key indicator of system openness and source characteristics. A ratio of 0.8–1 suggests a closed magmatic system with minimal external fluid involvement. Ratios <0.6 imply formation in distal, hydrothermal systems with external fluid input. Intermediate ratios (0.6–0.8) indicate mixed magmatic–hydrothermal environments with both internal and external fluid contributions (Pirajno and Smithies, 1992). In the studied granitoids, this ratio ranges from 0.60 to 0.75 (mean: 0.69), suggesting formation of tourmaline in an environment transitional between magmatic and hydrothermal regimes, likely reflecting fluid mixing involving magmatic-hydrothermal fluids and meteoric water during the final stages of crystallization. https://ijp.ui.ac.ir/article_30101.html IntroductionDelkan iron mine, geologically, located in the south of Bardeskan city. It is geologically located in the eastern part of the Central East Iran Microcontinent. Regarding structural division, the Delkan iron mine lies in the northeast of the Kashmar-Kerman tectonic zone and on the northeastern ridge of Kuh-e-Sarhangi. Some of the most important iron mines in Iran are located in the Kashmar-Kerman structural zone, for example, the Bafgh iron mines with a total reserve of 5 billion tons (Torabian, 2007).Geology of the AreaThe rock units in the study area are predominantly the metamorphosed units of schist, quartzite, limestone, dolomite, and amphibolite, belonging to Precambrian and the Cambrian units composed of limestone, dolomite, carbonaceous shales, schist, and quartzite. These rock units were subjected to intrusion of a plutonic stock, which gave rise to contact metamorphism halo and iron mineralization during the Silurian.Materials and MethodsFollowing the field investigations, for structural studies, 37 fault planes were structurally sampled, and 284 rock samples were taken from the surface and the archive of drilled cores in the mine for petrology, mineralogy, and mineralization studies.  73 microscopic sections of the samples were studied with an Olympus BX60F5 microscope at the University of Isfahan. Maps of the area were drawn using ArcGIS software. To measure the main oxides, 36 rock samples were taken and after preparation using the peroxide fusion method, were analyzed by the use of the ICP-OES technique. δ18O stable isotope analyses were carried out on 2 magnetite and 2 quartz samples. Also, δ 34 S stable isotope analysis were performed on 2 pyrite samples. All isotope analyses were carried out at the Stable Isotope Research Laboratory of Arak University (SIRL).Mineralization, Alterations, Mineralogy and MineralographyIron mineralization in the Delkan mine is observed in the two forms: 1) Iron oxide apatite with disseminated and veinlet texture within the monzonite intrusive stock, 2) Massive proximal and distal magnetite without apatite.Alterations observed in the Delkan deposit can be divided into prograde skarn, sodic, calcic, phyllic-silicic, and secondary carbonate alteration in order of occurrence. The intensity and spread of Prograde calc-silicate skarn alteration in the area are extremely limited.Pyrite occurs in two forms, pentagonal and anhedral to cubic. Primary quartz is pentagonal and secondary quartz is anhedral. Metamorphic garnets are red, isotropic, and metasomatic garnets are brown to green, and anhedral to euhedral. Albite is often replaced by other minerals and can be seen as pseudomorphs. Acicular actinolite with fibrous textures, and anhedral to subhedral apatite, euhedral to anhedral magnetite with massive, disseminated, and replacement textures are noticeable. In the central parts of the deposit, magnetite mineralizations are present in massive form without apatite, but at the margins of the intrusive stock, disseminated magnetite mineralized with apatite. Hematite is seen with disseminated, replacement, and martitization textures; in some cases, it is replaced by goethite or limonite. Chalcopyrite is observed in an anhedral shape.Galena and sphalerite mineralizations were also observed in shallow quartz veins of Delkan (Shabani et al., 2015).Fault Patterns and Their Relationship with Iron MineralizationTwo main fault distributions are extended in the mining area, including longitudinal faults trending northeast-southwest parallel to the extension of the Kuh-e-Sarhangi and NW-SE trending transverse faults almost perpendicular to the first group. According to studies (Sahandi et al., 2010; Nozaem, 2012), the Kuh-e-Sarhangi and Delkan areas have undergone multiple tectonic regime shifts between transpressional tectonic phases and extensional phases accompanied by volcanism and mineralization. It seems that the Silurian extensional phases in the longitudinal faults of the area under study have played a significant role in creating a suitable space for the intrusion of monzonite stock, which ultimately gave rise to the formation of proximal IOA and massive magnetite mineralization. Transverse faults have also played the role of escape routes for part of the hydrothermal fluid, caused the formation of distal mineralizations.Geochemistry of stable isotopesThe isotopic values of δ18O for magnetite samples in ranges from 8.6 and 10‰. According to several people (Einaudi et al., 1981; Bowman, 1998; Meinert et al., 2005), these values indicate a Juvenile origin for the hydrothermal fluid that caused the mineralization of massive magnetites without apatite.The values of δ18O for quartz samples are between 15.6 and 16.2‰. These values indicate isotopic equilibrium between the hydrothermal fluid and the host rock during the gradual cooling processes of the fluid.The isotopic δ34S values for pyrite samples ranging from 20.1 to 20.6‰. According to (Einaudi et al., 1981; Meinert et al., 2005), we consider the studied sulfur sources in the area of study to be non-magmatic and related to isotopic changes in the hydrothermal fluid in equilibrium with marine sulfates and host rocks as well.Discussion and ConclusionTwo types of iron mineralizations (skarn and kiruna) occurred in the Delkan mine, but most iron reserves in this deposit share similar characteristics to iron skarn deposits. Mineralization in the Delkan iron deposit has been subjected by several factors, of which the most important are  the following:A) The tectonic regime shifts between the transtensional and transcompressional regimes, which played a key role in intrusion and trapping of the intrusive stock,B) The direction and patterns of faults have been effective in determining the intrusion paths for both the plutonic stock and the juvenile hydrothermal fluids, mineralization type and locations of mineralizations,C) Differences in Oxidation state between the intrusive stock and the host rocks (especially the black carbonaceous phyllite layers that are highly reduced) plays a key role in the consumption of dissolved oxygen in the juvenile hydrothermal fluid due to intensity of decarbonation reactions between the fluid and these reducing layers, and as a result, the increase in the CO2 fugacity of the fluid, which will decrease the intensity of calc-silicate alterations (prograde skarn) and also a decrease in the amount of iron skarn mineralizations. https://ijp.ui.ac.ir/article_30247.html Introduction The Central Iran zone represents one of the most significant geological domains of Iran, characterized by a wide diversity of igneous, metamorphic, and sedimentary rocks formed through prolonged tectonic and magmatic processes. In the southeastern part of this zone, the Talahoueieh area, located north of Bam, occupies a structurally central Iranian position but is geodynamically situated along the active margin of the Urumieh–Dokhtar magmatic arc (UDMA). The development of this magmatic arc is attributed to the subduction of the Neo-Tethyan oceanic lithosphere beneath the Central Iran plate during the Cenozoic, making it one of the most important volcanic–plutonic and metallogenic belts in Iran (Berberian and King, 1981; Shahabpour, 2005). The Talahoueieh area comprises a suite of Eocene volcanic and volcaniclastic rocks, andesitic–dacitic dykes, and shallow to semi-deep intrusive bodies of granodioritic and monzonitic composition. These lithological assemblages clearly reflect multiple pulses of magmatic activity within an active tectonic setting. In several parts of the area, the igneous units are affected by widespread hydrothermal alteration, including silicic, argillic, chloritic, and carbonate assemblages. Field observations, petrographic characteristics, and preliminary geochemical data suggest a close genetic relationship between magmatism and base- and precious-metal mineralization The presence of extensive alteration zones, quartz vein–veinlet systems, and sulfide minerals such as pyrite, sphalerite, galena, and chalcopyrite indicates a strong potential for intermediate-sulfidation epithermal mineralization. Such deposits are commonly associated with calc-alkaline subvolcanic intrusions emplaced along active fault zones and are characterized by intense hydrothermal alteration. Accordingly, the Talahoueieh area represents a promising exploration target in the southeastern part of the Central Iran zone. In this study, whole-rock geochemical data obtained by ICP-MS and XRF analyses, together with detailed petrographic and ore microscopic studies, are used to constrain the petrogenesis, magma evolution, crystallization and differentiation processes, and their genetic links to alteration and mineralization. The ultimate goal is to develop a comprehensive model for the origin, evolution, and metallogenic role of igneous rocks in the Talahoueieh area. Research Method The study was conducted through fieldwork and laboratory analyses. A 1:10,000 geological map of the area was prepared, and 62 rock samples were collected. Of these, 35 were used for petrographic studies, while 19 representative samples (5 intrusive and 14 volcanic) were analyzed by XRF and ICP-MS at the Zarazma Laboratory (Kerman, Iran). The geochemical data were processed using Excel and GCDkit software to evaluate the geochemical and tectonic characteristics of the studied rocks. Regional Geology Magmatic activity in the UDMA lasted from the Eocene to the Quaternary, peaking in the Eocene. A shift from calc-alkaline to adakitic magmas in the early Miocene enhanced magma fertility, promoting porphyry mineralization. In the southeastern UDMA (Kerman copper belt), mineralization occurred mainly during the late Oligocene to Miocene. Key volcanic complexes include Bahr Aseman (Middle Eocene), Razak (Late Eocene), and Hazar (Middle Oligocene), showing a near-complete Cenozoic volcanic–sedimentary succession, with Eocene units being the most significant. In the Talahoueieh area, exposed rocks are dominated by volcano-sedimentary units (tuffaceous shale, conglomerate, and limestone), with central volcanic tuffs and dacitic–andesitic rocks forming elevated areas. Intrusive bodies are limited but locally associated with skarn-type mineralization. Alteration and Mineralization In the Talahoueieh deposit, hydrothermal alteration is widespread and, dominated by argillic, silicic, chloritic, and advanced argillic types, with argillic alteration being the most extensive and closely linked to mineralized zones. This reflects mid- to late-stage acidic hydrothermal activity. Potassic and phyllic alterations were not observed. Polymetallic vein-type mineralization (Cu, Pb, Zn, Ag) mainly occurs in Eocene volcanic units, especially pyroclastic tuffs and andesites, in the form of veins, veinlets, replacement, and open-space fillings, and is structurally controlled by structural features. Key minerals include chalcopyrite, bornite, malachite, azurite, chrysocolla, galena, cerussite, sphalerite, and hemimorphite. Copper mineralization shows oxidized zones at the surface and sulfide zones at depth, while Pb and Zn occurrences are sporadic. Mineralization is controlled by a combination of structural, lithological, and hydrothermal factors, emphasizing its economic potential and guiding future exploration. Discussion Calc-alkaline magmas typically form in subduction-related volcanic arcs and are characterized by high SiO₂, low Fe/Mg ratios, and mineral assemblages including plagioclase, hornblende, and biotite. These magmas are commonly associated with porphyry Cu–Au systems. In contrast, shoshonitic magmas have higher K₂O and K₂O/Na₂O ratios, are enriched in LILE and LREE, and are often linked to epithermal Au mineralization. The intrusive and volcanic rocks of the Talahoueieh area (granite, granodiorite, rhyolite, dacite, and andesite) exhibit high Al₂O₃ and K₂O contents, reflecting partial melting of a metasomatized mantle source and subduction-related arc magmatism. The coexistence of calc-alkaline and shoshonitic compositions indicates an active arc environment and late-stage magmatic evolution, providing favorable conditions for widespread alteration zones and hydrothermal systems. These geochemical characteristics highlight the economic potential of the area, particularly for porphyry Cu–Au and epithermal Au–Ag mineralization. Conclusion In the Talahoueieh polymetallic deposit, the exposed rock units mainly consist of Eocene volcano-sedimentary rocks, particularly tuffs, along with minor Quaternary deposits, while volcanic (andesite, rhyolite, dacite) and intrusive (granite, granodiorite) bodies are limited and scattered. The area is dominated by pyroclastic units, with intrusive and volcanic rocks playing a marginal tectonic role. Extensive hydrothermal activity has produced argillic, advanced argillic, propylitic, and silicic alterations, primarily hosted in pyroclastic units and structurally aligned along a NW–SE trend. This indicates strong structural control by faults and fractures that served as fluid pathways. Geochemical features, including low Nb/Ti ratios, negative Ti anomalies, and high K₂O, Al₂O₃, and LILE/HFSE ratios, suggest a continental arc volcanic environment with a close genetic link to calc-alkaline and shoshonitic magmas. Magmatic evolution in the area, driven by subduction-related processes and arc volcanism, created favorable conditions for the development of hydrothermal systems and polymetallic mineralization. https://ijp.ui.ac.ir/article_30161.html The studied granitoids (Astaneh and Aligudarz) are part of the Sanandaj–Sirjan Zone. These granitoid bodies mainly consist of granite, quartz diorite, tonalite, and granodiorite. Tourmalinization in these areas occurs within the alteration zone adjacent to and under the influence of the intrusive bodies on pelitic rocks and is directly associated with the hydrothermal system. Based on field and microscopic studies, tourmalines are classified into several types, including nodular tourmalines, layered tourmalines, disseminated tourmalines, pegmatitic tourmalines, and patchy or irregular tourmalines. According to geochemical diagrams, these tourmalines belong to the alkali group and possess schorl–dravite solid solution compositions. These tourmalines are associated with quartz–tourmaline rocks, metapelites, Ca-poor metapsamites, and Al-rich coexisting metapelites. The observed chemical zoning in this mineral indicates a hydrothermal origin and an open-system environment. Compared to the Astaneh tourmalines, the Aligudarz tourmalines formed at a greater distance from the granitoid body, and in both regions, the predominant source for tourmaline formation is primarily external https://ijp.ui.ac.ir/article_30219.html The Neybaz high-grade metamorphic complex is located in the western domain of the Central Iranian microcontinent, situated between the two basement faults of Chatak-Neybaz and Chapedony. Within this complex, metamorphosed mafic rocks are found as small masses in contact with and within gneisses that exhibit granulite facies metamorphic grade. The high-grade metamorphism in these rocks led to the appearance of a mineral paragenesis primarily composed of clinopyroxene and orthopyroxene, euhedral garnets, amphibole, and plagioclase. Geochemical investigations of these granulites indicate that their protoliths ranged from basalt to andesite and basaltic andesite, showing a calc-alkaline and tholeiitic affinity. Lithogeochemical variation diagrams suggest that these rocks formed in a plate margin setting. Furthermore, the close association of the mafic granulites with gneisses, some of which have a metagraywacke protolith, points to their origin from an active plate Margin. Spidergrams normalized to the primitive mantle and chondrite show enrichment in light rare earth elements (LREEs) relative to heavy rare earth elements (HREEs), enrichment of LIL elements, and depletion of HFS elements, confirming the involvement of both mantle and crustal sources in the formation of the protoliths. Based on the geochemical data and structural evidence, this study suggests that the formation of the mafic melts in the Neybaz complex was related to cratonization processes in an active margin environment during the Paleo- to Neoproterozoic era. The geochemical characteristics of these granulites, including negative Nb and Ti anomalies in the spidergrams, link their origin to arc magmatism (such as island arc tholeiites or calc-alkaline basalts). https://ijp.ui.ac.ir/article_30317.html The Late Eocene-Early Oligocene (29-35 Ma) and Late Oligocene (24-25 Ma) granitoid bodies in the Mardehak district, east of Jiroft, within the Jabal Barez granitoid complex (southeastern part of the Urumiyeh-Dokhtar magmatic zone, southern Kerman), represent a prominent example of a diachronous magmatic event of the active continental margin arc type. These granitoid bodies consist of diorite, quartz diorite, quartz monzonite, granodiorite, granite, and alkali granite with a calc-alkaline nature, metaluminous to slightly peraluminous, and with subduction zone geochemical affinities. A significant and nearly constant increase in Sr/Nd and Th/Yb ratios in the samples highlights the prominent role of oceanic slab-derived aqueous fluids in the metasomatism of the mantle wedge and the source region of the granitoid magma. U-Pb dating on zircon crystals from these rocks reveals the generation and emplacement of granitoid magma from partial melting of Zagros Neo-Tethys subducting oceanic slab and above mantle wedge in two separate events during the Late Eocene-Early Oligocene (35–29 Ma) and Late Oligocene (25–24 Ma), in a syn- to post-collisional tectonic regime. https://ijp.ui.ac.ir/article_30326.html The granitoid bodies of the Sarbijan–Dalfard district within the Jebal-e-Barez mountain range form part of the Oligocene–Miocene magmatism of the southeastern part of Urumiyeh–Dokhtar magmatic belt. These intrusions consist of diorite, monzodiorite, granodiorite and granite and display predominantly anhedral to subhedral granular textures. Biotite, as the main mafic mineral in most of these bodies, has a primary magmatic origin and a magnesium-rich composition. Thermometry based on Ti-in-biotite indicates closure temperatures of 600–730 °C for this mineral, consistent with crystallization and replacement conditions of calc-alkaline granitoid magmas. Barometry based on total Al in biotite indicates emplacement of these intrusive bodies at pressures of 1–2.5 kbar, corresponding to shallow upper crustal depths (approximately 3–7 km). Oxygen fugacity and the coexistence of Mg-rich biotite with iron-oxide phases imply oxidizing conditions and affiliation of these granitoids to the magnetite series with copper mineralization potential. Field, petrographic and mineral chemistry evidence collectively indicate that the granitoid bodies of the Sarbijan–Dalfard district were derived from a calc-alkaline, metaluminous, I-type granitoid magma in a magmatic-arc environment contemporaneous with subduction-related collision during the Oligocene–Miocene. These results are consistent with the obtained founding’s from proposed models for arc magmatism in the southern part of the Urumiyeh–Dokhtar magmatic belt.