دانشگاه اصفهان پترولوژی 2228-5210 15 3 2024 09 22 Petrogenesis and Tectonic Implications of Bakter intrusive complex (South Sonqor, West of Iran) سنگ‌زایی و جایگاه زمین‌ساختی مجموعة آذرین درونیِ بَکتِر (جنوب سنقر، باختر ایران) 1 22 28409 10.22108/ijp.2024.137533.1298 FA جمال مشمایی دانشجوی دکتری، گروه ژئو‌شیمی، دانشکده علوم زمین، دانشگاه خوارزمی، تهران، ایران 0009-0005-1226-5254 شهریار محمودی دانشیار، گروه ژئوشیمی، دانشکده علوم زمین، دانشگاه خوارزمی، تهران، ایران میر علی اصغر مختاری دانشیار، گروه زمین‌شناسی، دانشکده علوم، دانشگاه زنجان، زنجان 0009-0005-1226-5254 Journal Article 2023 05 28 Introduction The Sanandaj-Sirjan Zone formed a piece of the northeastern section of the Gondwana continent during the Paleozoic era and separated it from the Asian plate by the Paleo-Tethys Ocean (Golonka., 2004). During the Middle and Late Triassic, coinciding the closure of the Paleo-Tethys, a rift called the Neo-Tethys Sea developed along the Zagros region, separating the Sanandaj-Sirjan zone from the Arabian plate (part of Gondwana). Crustal subduction is thought to have initiated in the Late Triassic to Early Jurassic (Berberian, 1981). This subduction led to the deformation of rocks and emplacement of intrusive masses during the Late Triassic in the southern part of the Sanandaj-Sirjan zone, and the emplacement of various masses from gabbroic to granitic rocks during the earlier times in the northern part of the zone from the Middle Jurassic (Shahbazi et al., 2010; Mahmoudi et al., 2011) to the Middle Cretaceous (Ghalamghash et al., 2009) and Early Eocene (Ahadnejad et al., 2010). The closure of the Neo-Tethys Sea and the subduction of the oceanic crust are often been associated with the emplacement of ophiolites along the Zagros Zone during the Late Cretaceous to Paleocene (Agard et al., 2005), in addition to some granitoid bodies of the Upper Eocene to Oligocene. According to (Berberian 1981 and Azizi and Moinevaziri, 2009), these bodies and their ages indicate the continuation of the oceanic crustal termination and the collision between the Arabian plate and Central Iran during the Neogene. Several valuable studies have been conducted on the magmatism of intrusive masses within the Sanandaj-Sirjan Zone, including the southern Dehgalan (Sarjoughian et al., 2015), northwest of Azna (Shabanian et al., 2009), Cheshme Sefid (Davoudian et al., 2007), Qorveh-Mobarakabad (Azizi and Asahara., 2013), southeastern Saqqez, and Almoghlaq batholith. Regional Geology The study area is located in the northwestern part of the Sanandaj-Sirjan Zone, southeast of the city of Sanandaj in Kermanshah Province. It lies within the geographical longitudes of '35°47 to '30°47 east and latitudes of '35°34 to '38°34 north, within the southwestern portion of the 1:100,000 Sanandaj geological sheet. The upper Cretaceous phyllitic units are intruded by syenitic-gabbroic intrusive masses and have undergone metamorphism and transformation into hornfels due to neighboring intrusive masses and associated metamorphism. The geological map at a scale of 1:25,000 (Mokhtari and Kohestani, 2018) has delineated the rock units of the area (Figure 1). Research Methodology Following the field studies and mapping with satellite images, field observations were conducted. Microscopic studies were carried out on the collected samples. Following the examination of thin sections of the rocks, 12 samples exhibiting the least evidence of secondary processes, including mineral alteration, cavity filling, and the presence of secondary veins and fractures, were selected. Subsequently, the samples were dispatchedare sent to the Zara-Azma Laboratory for chemical analysis. This entailed theThrough this analysis determination of the abundance of trace and rare earth elements using are determined by applying the inductively coupled plasma mass spectrometry (ICP-MS) and major oxides using the fusion method. Petrography: The study area consists of gabbro, syenite, alkali syenite, and quartz syenite. The dominant textures are hypidiomorphic granular, poikilitic, perthitic, and granophyric in the syenites, as well as sieve-textured fabric. All rock types trending northeast-southwest. Gabbroic Intrusions: Gabbroic intrusions are present in the southern part of the Baetar intrusive complex and at the margin of the syenitic intrusion. In the northern margin of the syenitic intrusion, two small outcrops of gabbroic intrusion are observed, where one is in contact with the syenitic intrusion, and the other is within the units of hornfelsed shale, siltstone, and metamorphos sandstone of Upper Cretaceous era. Syenitic Intrusion: In the central region of the Bakter intrusive complex, the outcrops of syenitic intrusion are widespead. The syenitic intrusion is in close proximity to the gabbroic intrusion, particularly in the southern region. Geochemistry Based on whole rock geochemical data, especially the La/Yb vs. La ratio, these rocks share the same genesis. Geochemical data, including LREE enrichment compared to HREE, positive Pb anomaly, and depletion of Nb and Ti, reveal the divergent regimes in a back-arc zone, through which the primary magmatic melts are generated in the Bakter intrusive complex. The presented geochemical patterns indicate that the parental magma of the studied rock group is derived from an enriched or metasomatized garnet lherzolite with a degree of partial melting within 5% to 15% range.. Conclusion Field studies, petrography, and geochemical analysis run on the subject region reveal that it is composed of mafic and felsic rocks, with the felsic rocks mainly consisting of syenite, alkaline syenite, and quartz syenite, while the mafic rocks are of a gabbroic composition. Spider diagrams normalized to primitive mantle compositions reveal the enrichment in large-ion lithophile elements (LILE) and light rare earth elements (LREE) compared to high field strength elements (HFSE), with negative anomalies observed in niobium (Nb) and titanium (Ti). The parental magma of the studied plutonic rocks is derived from low degrees of partial melting (5-15%) of a garnet-bearing lherzolite source at depths of 95-110 kilometers. Considering that the intrusive rocks of the Baetar region are associated with post-collisional activities and the presence of a thin and stretched lithosphere is appropriate for their formation, it is assumed that a secondary subduction with a slab break-off mechanism occurred in the Sanandaj-Sirjan Zone for a relatively long period after the initial collision. مجموعة‌ آذرین درونی بَکتِر در شهرستان سنقر، استان کرمانشاه و در پهنة زمین‌ساختی سنندج-سیرجان جای دارد. این مجموعه شامل گابرو، سینیت، آلکالی‌سینیت و کوارتز سینیت است. در بررسی‌های سنگ‌نگاریِ سینیت‌ها، بافت‌های هیپ‌ایدیومورف گرانولار، پویی‌کیلیتیک، پرتیت و گرانوفیری و همچنین، بافت غربالی دیده می‌شود. آلکالی‌فلدسپار، پلاژیوکلاز، کلینوپیروکسن، آمفیبول و بیوتیت از کانی‌های اصلی سینیت‌ها هستند. ویژگی‌های بافتی مانند بافت‌های ناتعادلی (مانند بافت غربالی در پلاژیوکلاز) را می‎توان پیامد تحولات ماگمایی در هنگام جایگزینی در آشیانه‌های ماگمایی متعدد و آمیختگیِ فازهای جدایش‌یافته در این آشیانه‌های فرعی با پوسته و ماگمای مافیک دانست. ذوب‌بخشی و آمیختگی مهم‌ترین عوامل پیدایش سنگ‌های آذرین درونی منطقه هستند. نسبت La/Yb در برابر La رخداد این فرایند را آشکار می‌کند. داده‌های به‌دست‌آمده در این پژوهش شامل غنی‌شدگی عنصرهای LREE در مقایسه با HREE، آنومالی مثبت Pb، تهی‌شدگی عنصرهای Nb و Ti و دیگر داده‌ها، نقش احتمالی آلایش پوسته‌ای در بخش‌های اسیدی مجموعة بَکتِر است روندهای دیده‌شده در تحول ماگمای سازنده این تودة آذرین درونی وابستگی مذاب‌های مادر این تودة آذرین درونی به فازهای کششی پس از برخورد و پشت‌کمان ماگمایی را نشان می‌دهند. الگوهای زمین‌شیمی نشان می‌دهند ماگمای مادر مجموعة سنگی بکتر شامل بخش اسیدی (سینیتی) و بخش بازیک (گابرویی) از یک گوشتة غنی‌شده یا دگرنهادشده با ترکیب گارنت لرزولیت با درجة ذوب‌بخشی 5 تا 15 درصد پدید آمده است. با توجه به بررسی نمودارهای زمین‌شیمیایی، توده‌های آذرین درونی بکتر در پی سازوکار زمین‌ساختی کششی یا نازک‌شدگی پوسته‌ای در یک پهنة پسابرخوردی میان دو پوستة قاره‌ای رخ داده‌اند. این سنگ‌ها در پی فرورانش پوستة اقیانوسیِ نئوتتیس به زیر صفحة ایران مرکزی در پهنة دگرگونی-ماگمایی و پس از برخورد پوستة قاره‌ای ایران مرکزی و عربی در پهنة سنندج-سیرجان پدید آمده‌اند.

https://ijp.ui.ac.ir/article_28409_7568e0d3e62df71c612ee01c9221b4a2.pdf

دانشگاه اصفهان پترولوژی 2228-5210 15 3 2024 09 22 Mineral chemistry and thermobarometry of Marzroud-Nabijan intrusive rocks (SW Kaleyba, NW Iran) شیمی کانی‏‌ها و دما –فشارسنجی توده‏های آذرین درونی مرزرود- نبی‌جان (جنوب‌باختری کلیبر، شمال‌باختری ایران) 23 44 27988 10.22108/ijp.2023.138455.1306 FA صدیقه صدری دانشجوی دکتری (سنگ‌شناسی)، گروه زمین‌شناسی، دانشکده علوم طبیعی، دانشگاه تبریز، تبریز، ایران نصیر عامل دانشیار، گروه زمین‌شناسی، دانشکده علوم طبیعی، دانشگاه تبریز، تبریز، ایران محسن مؤید استاد، گروه زمین‌شناسی، دانشکده علوم طبیعی، دانشگاه تبریز، تبریز، ایران Journal Article 2023 07 19 Introduction The Marzroud- Nabijan intrusive rocks are located in the Alborz-Azarbaijan zone, NW Iran. The rocks intruded the Cretaceous volcanic and sedimentary rocks. The studies conducted in the study area were in the form of a master's thesis, and the study of mineral chemistry was not conducted. Materials and methods Folloing the field studies, and sampling of intrusions of Marzroud and Nabijan, four fresh (non-altered) samples were selected for Electron-probe microanalysis (EPMA) carried out at the Carleton University, Canada. The EPMA was performed using a Wavelength Dispersive X-ray (WDX)microprobe camera with an accelerating voltage of 20 kV and a beam current of 20 nA to determine the major elements in the minerals for thermal and pressure studies. The results of these analyses are presented in Tables 1 to 4. The obtained data were evaluated and analyzed using Excel software. Results and discussions EPMA results of clinopyroxene from the study area are represented in Table 1. The clinopyroxenes in the studied samples fall into the iron-magnesium-calcium pyroxenes Quad field (Morimoto et al., 1988). The compositions for the clinopyroxene are demonstrated in terms of mole fraction of enstatite, ferrosilite, and wollastonite (Morimoto et al., 1988). In this diagram, the resulting data yielded chiefly diopside. In the diagram of Na+Al(IV) versus Al(IV)+2Ti+Cr, all analyzed pyroxenes exhibit a high oxygen fugacity range (Schweitzer et al., 1979). Magma series is subdivided into sub-alkaline, alkaline, and peralkaline, using Al2O3 and SiO2 values in the chemical composition of pyroxenes (Le Bas, 1962). The samples of the study area fall within the subalkaline range. In the diagram of Ca vs. Ti+Cr, pyroxenes, the samples were plotted in the volcanic arcs (Dorais, 1990). In the Si versus Al diagram, all samples under study lie above the saturation line of the tetrahedral position (Si+Al=2). This suggests that the tetrahedral sites in the clinopyroxene structure are completely occupied by Al and Si cations present in the pyroxene composition, and Ti cannot enter the pyroxene structure. One of the ferromagnesian minerals accompanying the felsic and intermediate rocks is biotite. Based on the EPMA results, as seen in Figure A-6, the biotites in the gabbro-diorite of Marzrud belong to the primary biotite type. The composition of biotites in the gabbro-diorite of Marzrud is the range of biotite based on the Fe / Fe + Mg > 0.33. The magma series responsible for the formation of biotites are plotted within the calc-alkaline range in both study areas. EPMA results of amphibole from the Marzroud and Nabijan are represented in Figure 7-B. It shows amphiboles are actinolitic hornblende in Marzroud monzogranitic body, actinolite in Nabijan granodioritic body, and tschermakitic hornblende in Nabijan gabbroic body. In the diagram of Al versus Fe/Fe+Mg, all analyzed amphiboles exhibit a high oxygen fugacity range (Helmy et al., 2004) indicating the intrusive masses of the region were formed concerning convergent plate boundaries (Anderson and Smith, 1995). Amphiboles belongs to the calcic type based on NaB<0.5, Ca>1.3 and (Ca+Na)B≥1 (Leake et al., 1997) pointing to the I – type granitoids nature. This is because type I granitoids contain a high content of CaO, leading to the crystallization of hornblende. All analyzed amphiboles are situated in the subalkaline range (Molina et al., 2009). In the Ti versus Al diagram, all amphiboles contain less than 0.5 cation Ti in their chemical formula. In the Ti versus Al diagram, all amphiboles contain less than 0.5 cation Ti in their chemical formula. The analyzed amphiboles from the Nabijan show that the amount of Ti and AlIV is higher in gabbro amphiboles than in granodiorite amphiboles. The number of cations of Ti and AlIV has a direct relationship with the rise in temperature in the formation time of minerals, also with the increase of Si in the crystallization system amount of AlIV in the amphibole structure decreases. In the Mg+Fe versus AlIV diagram, the analyzed samples exhibit a negative trend, indicating chemically controlled substitution. The feldspar composition is andesine - labradorite in Marzroud gabbrodioritic rock, andesine and orthoclase in Marzroud monzogranitic rock. The feldspar is andesine and oligoclase in Nabijan granodiorite and labradorite to bytonite in the Nabijan gabbroic body. The calculated emplacement pressure for the intrusive masses at the study areas, using the Al(total)value in the amphibole lattice, is approximately 0.8 kbar for Nabijan granodiorite and 0.5 kbar for Marzroud monzogranite (Schmidt, 1992). Due to the lack of paragenetic assemblage in Nabijan gabbro, the pressure corresponds to the crystallization depth of hornblende. The calculated pressure for the amphibole in gabbro is about 6.5 kbar, which corresponds to the pressure of hornblende crystallization during the hornblende gabbro formation. Thermometry of the intrusive masses was performed using the Ti content in amphibole (Otten, 1984) in granodiorite at Nabijan shows a temperature of 677°C, gabbro the Nabijan indicates about 992°C and monzogranite the Marzrud is 677.3°C. Conclusion Based on the mineral chemistry of mafic intrusive masses at study area, the composition of clinopyroxenes is in the diopside range. Amphibole minerals are calcic in two areas. The Nabijan plutons amphibole are actinolite in granodiorite and tschermakitic hornblende in gabbro. The hornblende in Marzroud monzogranite is actinolite. The Marzroud gabbrodiorite biotites with Fe/(Fe+Mg)>3 are enriched in Mg. The feldspar composition is andesine - labradorite in Marzroud gabbrodiorite, andesine and K- feldspars in Marzroud monzogranitic rocks. The plagioclase composition is andesine and oligoclase in Nabijan granodiorite and labradorite to bytonite in Nabijan gabbroic body. The chemistry nature of the biotite, amphiboles, and pyroxenes under study indicates that this intrusion is calc-alkaline affinity crystallized in a subduction zone setting. توده‏های آذرین درونی نبی‌جان و مرزرود به سن الیگوسن در جنوب‌باختری شهرستان کلیبر، شمال‌باختری ایران و در پهنة البرز باختری- آذربایجان جای گرفته‌اند. توده‏های آذرین درونی منطقه درون سنگ‌های آتشفشانی- رسوبی کرتاسه تزریق شده‌اند. ترکیب سنگ‌شناسی توده‏‌های منطقة مرزرود گابرو- دیوریت و مونزوگرانیت و در منطقة نبی‌جان گابرو و گرانودیوریت است. بررسی شیمی کانی‏‌ها نشان می‏‌دهد ترکیب کلینوپیروکسن توده‏‌های مافیک منطقة نبی‌جان و مرزرود از نوع دیوپسید است. آمفیبول‏‌های هر دو منطقه در گروه کلسیک جای می‏‌گیرند. آمفیبول‏‌های توده گرانودیوریتی نبی‌جان از نوع اکتینولیت، گابرو نبی‌جان هورنبلند چرماکیتی و در مونزوگرانیت‏‌های منطقة مرزرود از نوع هورنبلند اکتینولیتی هستند. در بیوتیت‏‌های گابرودیوریت مرزرود نسبت 33/0Fe/(Fe+Mg)> است و از منیزیم سرشار هستند. ترکیب فلدسپار در تودة گابرودیوریتی مرزرود، آندزین و لابرادوریت، در مونزوگرانیت مرزرود، آندزین به‌همراه ارتوکلاز، درگرانودیوریت نبی‌جان، آندزین- الیگوکلاز و درگابروی نبی‌جان، لابرادوریت تا بیتونیت است‌. با بهره‌گیری از شیمی کانی‌های کلینوپیروکسن، آمفیبول، بیوتیت و فلدسپارها دما و فشار پیدایش گرانودیوریت نبی‌جان برابر با ℃677 و 7/0- 85/0 کیلوبار، گابرو نبی‏‌جان برابر با ℃992، مونزوگرانیت مرزرود برابر با ℃3/677 و 45/0- 5/0 کیلوبار به‌دست آمد. شیمی کانی‏‌های پیروکسن، بیوتیت و آمفیبول نشان می‌دهد توده‏های آذرین درونی منطقه به سری کالک‌آلکالن متعلق هستند و در محیط وابسته به فرورانش پدید آمده‌اند.

https://ijp.ui.ac.ir/article_27988_e8f7b43db704762466fc1701750f0040.pdf

دانشگاه اصفهان پترولوژی 2228-5210 15 3 2024 09 22 Study of Sari-Tappeh adakitic magmatism, NW Marand, with emphasis on tectono-magmatic setting بررسی ماگماتیسم آداکیتی ساریتپه، شمال مرند، با تأکید بر خاستگاه تکتونو-ماگمایی 45 68 28995 10.22108/ijp.2024.142752.1342 FA مروت فریدآزاد استادیار، دانشکده مهندسی معدن، دانشگاه صنعتی سهند تبریز، تبریز، ایران ناصر اشرفی استادیار، گروه زمین شناسی، دانشگاه پیام نور، ایران اسماعیل خان چوبان سازمان صنعت، معدن و تجارت، استان آذربایجان شرقی، تبریز، ایران Journal Article 2024 09 11 Introduction The Cenozoic magmas in Urmia-Dokhtar Magmatic Belt (UDMB) show a wide range of composition. Among them, study of adakitic type magmatism of this belt (or arc) has gained momentum among the researchers on petrological studies. The origin of most adakitic magmas in Iran is attributed to the subducting oceanic lithosphere melting (Jahangiri, 2007; Sahfaii Moghadam et al., 2016; Jamshidi et al., 2018; Omrani, 2018). Identifying the spatial and temporal location and a more detailed description of the characteristics of adakitic magmatism in northwest Iran, as an important section of the UDMB, can lead to a better understanding of the history of late Cenozoic magmatism, where a wide range of normal calc-alkaline, alkaline and shoshonitic magmas are formed extensively. In this regard, the present study examines the petrology, geochemistry and tectonic environment of the adakitic volcanic rocks between Sari-Teppeh and Zonouz (north of Marand city, located in East Azarbaijan province). Geological Background The subduction of the Neotethys under the central Iranian plate during the Late Cretaceous to the Paleogene, followed by the collision of the Iranian and the Arabian plates (continental-continental collision), developed four structural zones in Iran. These structural zones with northwest-southeast trend are the Zagros Fold-Thrust belt, Sanandaj-Sirjan metamorphic and magmatic zone and Urmia-Dokhtar magmatic belt (Alavi, 1994; Mohajjel et al., 2003). Omrani et al. (2008) have divided the volcanic rocks of Urmia-Dokhtar magmatic belt (including the study area) into two categories: Eocene and Miocene to Plio-Quaternary. Regionally, the Miocene-Pliocene volcanic rocks are outcrops in the form of composite volcanoes and of large and small domes with the composition of andesite, latite, trachyte, dacite and rhyolite. Volcanic rocks of the studied area include andesite and dacite in gray to light gray color. Field studies of the sub-volcanic domes show their penetration into the Miocene marl, shale and sandstone sediments. Therefore, the age of Upper Miocene to Pliocene can be considered for the volcanic rocks. Analytical Methods Following the sampling, about 40 thin sections were prepared for petrographic studies. Fifteen samples with the least alteration are selected and analyzed for major oxides and minor elements by XRF method in the laboratory of the Geological Survey of Iran. The major elements of 6 samples out of the 15 are analyzed by ICP-OES (lithium metaborate-nitric acid dissolution method) and trace elements, including rare-earth elements (REEs), are analyzed by the ICP-MS (Four-acid digestion method) at the Zar-Azma lab (Iran). Discussion The studied volcanic rocks have a dominant texture of porphyry with phenocrysts of plagioclase, hornblende and occasionally biotite and quartz that make up about 50% of the rock volume. Plagioclase phenocrysts have a variety of disequilibrium textures of sieve texture, state of corrosion, and chemical zoning, as well as alteration with different intensity to sericite, calcite and chlorite is observed in them. Hornblende phenocrysts are usually euhedral to subhedral with simple twinning and opacity rims. Based on the chemical classification by Le Bas et al. (1986), the studied rocks are andesite and dacite in composition. In addition, in the K2O versus silica diagram of Peccerillo and Taylor (1976), the samples show calc-alkaline characteristics. The rare earth elements (REEs) chondrite-normalized patterns for the samples indicate a large negative slope for the light and medium rare earth elements (LREE and MREE), while a relatively lower slope is observed for the heavy rare earth elements (HREE). Unlike andesite, dacite, and rhyolite sodic series (ADRs) of normal arc, the studied rocks have high Sr/Y and LaN/YbN ratios (respectively 31.21 to 115.96 and 7.49 to 29.66). Also these rocks have low values of Y (5.2 to 10.2 ppm) and YbN (2.39 to 4.78 ppm) and in the graphs of Y versus Sr/Y and (La/Yb)N versus YbN, are all plotted within the adakite field. Sari-Tappeh adakite samples have relatively low MgO values (<4.04 wt%) and show most of the characteristics of high-silica adakite (HSA). According to the Sr versus CaO+Na2O diagram by Martin et al. (2005), all samples are plotted within the HSA field. Also, the samples have high Sr and low Y values and medium to high Sr/Y ratios, which are typical features of HSA. The studied rocks show slightly more negative Nb and Ti anomalies compared to common arc andesites and dacites. They also show higher Sr/Y and (La/Yb)N ratios and lower Y and YbN values compared to normal arc rocks. All these geochemical features can be consistent with the characteristics of adakitic rocks resulting from partial melting of the subducting oceanic lithosphere or the lower continental crust (Martin et al., 2005; Castillo, 2006). The studied rocks have high Ba/Rb (38.3-71.28) and low Rb/Sr (0.22-0.02) ratios, which are compatible with an amphibole-containing origin rather than a phlogopite-containing origin. Combining the existing geochemical characteristics shows that the melting of an amphibolite source containing garnet can form the magma that formed the studied rocks. Conclusion The stratigraphic age of these rocks is middle Miocene and later and they were formed in a post-collision environment. Sari-Tappeh volcanic rocks have calc-alkaline nature. They show low values of Y and Yb and high values of Sr and Sr/Y along with medium values of MgO, which is consistent with the characteristic of high silica adakites. Based on the geochemical features of this magmatism and considering the tectono-magmatic models regarding adakitic magmatism, it appears that the partial melting model of oceanic basalt under the condition of garnet-amphibolite facies during the slab breaking-off the Neotethys can appropriately elucidate the formation of the studied rocks. پژوهش پیش‌رو به بررسی سنگ‌شناسی و زمین‌شیمی سنگ‌های آداکیتی می‌پردازد که به شکل گنبدهای آذرین نیمه‌بیرونی درون واحدهای میوسن نفوذ کرده‌اند. اهمیت بررسی چنین سنگ‌هایی از آنجاست که نشانگرهای خوبی دربارة تحول ژئودینامیکی در محیط‌های همگرا هستند و داده‌های ارزشمندی دربارة فرایندهای ماگمایی حاکم و چه‌بسا کانی‌زایی فراهم می‌کنند. سنگ‌های یادشده ترکیب حد واسط وآندزیتی دارند و بافت غالب آنها پورفیری است. پلاژیوکلاز، هورنبلند و گاهی کوارتز و بیوتیت از فراوان‌ترین فنوکریست‌ها هستند که در یک زمینة دانه‌ریز جای گرفته‌اند. سنگ‌های یادشده گرایش کالک‌آلکالن دارند و با داشتن ویژگی‌های زمین‌شیمیایی مانند MgO (4> درصدوزنی)، Y (ppm 18-5)، Yb (ppm 1-5/0) و عنصرهای خاکی کمیاب سنگین (HREEs) کم و Sr ( ppm603-284) و نسبتSr/Y (116-31) بالا ویژگی سنگ‌های آداکیتی را نشان می‌دهند. از ویژگی‌های مهم سنگ‌های آداکیتی ساری‌تپه می‌توان نسبت بالای CaO/Al2O3 و نسبت‌های کم K2O/Na2O، Nb/Ta و (La/Yb)N را بر شمرد. با توجه به ویژگی‌های زمین‌شیمیایی این ماگماتیسم، الگوی ذوب‌بخشی بازالت اقیانوسی در شرایط رخسارة گارنت-آمفیبولیت هنگام جداشدگی ورقة اقیانوسی نئوتتیس، برای پیدایش سنگ‌های ساری‌تپه پیشنهاد می‌شود.

https://ijp.ui.ac.ir/article_28995_82721303883f5ce22be775efec3d83ed.pdf

دانشگاه اصفهان پترولوژی 2228-5210 15 3 2024 09 22 Paleo-Tethys subduction to closure and the continental collision in the north of the eastern subcontinent of central Iran, Evidence from petrography and stable oxygen isotope in Chah Zard meta-granite in the east of Jandaq فرورانش و بسته‌شدن پوستة پالئوتتیس تا برخورد قاره‌ای در شمال خردقارة خاور-ایران مرکزی، برپایة شواهد سنگ‌نگاری و ایزوتوپ پایدار اکسیژن در متاگرانیت چاه‌زرد در خاور جندق 69 88 29011 10.22108/ijp.2024.142870.1343 FA مهدی اله‌یاری ابهری دانشجوی کارشناسی‌ارشد، گروه پترولوژی، دانشکده علوم‌پایه، دانشگاه تربیت مدرس، تهران، ایران نرگس شیردشت‌زاده استادیار، گروه پترولوژی، دانشکده علوم‌پایه، دانشگاه تربیت مدرس، تهران، ایران کریس هریس استاد، گروه زمین‌شناسی، دانشگاه کیپ‌تاون، کیپ‌تاون، آفریقای جنوبی محمدرضا قربانی دانشیار، گروه پترولوژی، دانشکده علوم‌پایه، دانشگاه تربیت مدرس، تهران، ایران Journal Article 2024 09 22 Introduction The Jandaq metamorphic complex is a part of the Yazd block in the Central Iran structural zone, and northwest of Khur, in the eastern part of the Central-East Iranian Microcontinent (CEIM) (Figure 1) (Heidarianmanesh et al. 2022). The Jandaq metamorphic complex (JMC) consists of metamorphic and meta-igneous rocks dated back to Late Permian- Early Jurassic periods. The JMC is characterized by the presence of metamorphosed peridotites, schists, amphibolites, migmatites, intruded by granites and pegmatite dikes (Romanko et al. 1984; Bagheri 2007; Tabatabaeimanesh and Sharifi, 2011; Muttoni et al. 2015; Jamshidzaei et al. 2021). Thermobarometry studies (Heidarianmanesh et al. 2022) showed a regional transformation from amphibolite to granulite facies, attributed to medium P/T Burrovian metamorphism during crustal thickening in subduction zones or continental collision due to subduction of the Paleo-Tethys Ocean and subsequent tectonic activity in the region. The primary objective of the present study is to provide evidence of Paleo-Tethys subduction and the resulting continental collision in the northern CEIM. Therefore, this study focuses on Chah Zard meta-granite, intruded the various JMC metamorphic rocks. Petrographic observations as well as stable oxygen isotope analysis of quartz and whole-rock samples were conducted to provide deeper insight into the magmatic and metamorphic history of the JMC area. Research Methods The methodology of this study involved extensive fieldwork, petrographic analysis, and stable oxygen isotope studies. Field observations were concentrated on the contact between the Chah Zard granite and the surrounding metamorphic rocks. Samples from various parts of the JMC were collected, and thin sections were prepared for petrographic examination. Stable oxygen isotope data from quartz crystals and whole-rock samples were analyzed to assess the origin and the evolution of the granitic body and the rocks surrounding it as well. All O-isotope data were carried out at the University of Cape Town. All the isotope ratios were measured using a Finnigan Delta XP mass spectrometer in dual-inlet mode. An internal standard (Murchison Quartz - MQ, δ18O=+10.1‰) was analyzed to calibrate the data to SMOW scale. The long-term variability of MQ suggests a 2σ error of 0.16‰. Discussion The petrographic study identified two main phases of regional metamorphism. The first phase (M1) occurred prior to intrusion of the Chah Zard granite, during the subduction of the Paleo-Tethys Oceanic crust in the Carboniferous period. The second phase (M2) happened during/after continental collision. Petrographic evidences such as grain boundary migration (GBM) in quartz, the formation of myrmekite, flame perthite in feldspars, and high-pressure garnet crystallization suggests that the granite experienced high-pressure metamorphism in the course of the continental collision. Additionally, based on modal ratios and δ18O value of minerals, ∆quartz-magma for the Bushveld granite is estimated as 1.11‰ (Fourie and Harris 2011). In the absence of stable oxygen isotope data for other minerals, it is assumed that the value of ∆quartz-magma is equal to 1.1 ‰, and accordingly, the δ18O value in the Chah Zard granite is equal to 10.8 ‰ (n: 4; Table 1) consistent with its amount in magmatic rocks of mantle origin. Moreover, granites with high δ18O values (greater than 10 ‰) are believed to likely contain a significant fraction of mantle-derived melts with δ18O ranging from 5.7 to 6.5 ‰ (e.g., Hoefs, 2009). Based on the presence of magmatic garnets of I-type granites (Figure 7) coupled with the oxygen stable isotopic data, the origin of the rocks of Chah Zard is possibly the melting of felsic parts of the subducting plate with minimal mantle contamination during ascent. Therefore, the petrographic and isotopic evidence from this study suggests that the Chah Zard granite was generated from a small degree of partial melting of a subducting felsic slab. The low δ18O values further indicate limited interaction with the continental crust as the magma ascended. The presence of high-pressure metamorphic garnets (Figure 7) in the meta-granite confirms the occurrence of regional metamorphism associated with the continental collision. Moreover, the present data also emphasize the significance of studying the deformed granitic rocks like the Chah Zard meta-granite to reconstruct the tectonic history of the region. Conclusions In conclusion, the study of Chah Zard meta-granite offers valuable insights into the subduction of the Paleo-Tethys Ocean and its subsequent closure through continental collision in the CEIM. The petrographic evidences (deformation metamorphism of the granite and the magmatic garnets of I-type granites) and stable oxygen isotopic data (10.8 ‰ for the granite) reveal that the region experienced two significant phases of regional metamorphism: the first, related to the subduction of oceanic crust during the Carboniferous and the second, linked to the continental collision in the Late Jurassic. Following the intrusion of the Chah Zard granite into pre-existing metamorphic rocks, it was deformed and metamorphosed into a meta-granite during the final stages of Paleo-Tethys closure. The magmatic garnet composition and isotopic analysis confirms that this granite originated from a mantle-derived magma with minimal crustal contamination. Ultimately, this research contributes to a more comprehensive understanding of the tectonic history of northern CEIM and its role in the broader evolution of the Paleo-Tethys Ocean. این پژوهش شواهد فرورانش پالئوتتیس تا برخورد قاره‌ای در شمال خردقارة خاور ایران مرکزی برپایة سنگ‌نگاری و ایزوتوپ پایدار اکسیژن در کوارتز در متاگرانیت چاه‌زرد در خاور جندق را ارائه می‌دهد. در این منطقه، گرانیتوییدهای ژوراسیک میانی افیولیت جندق و سنگ‌های دگرگونی منطقه را قطع کرده‌اند. بررسی‌های میدانی و سنگ‌نگاری روی نمونه‌های متاگرانیت‌ جندق نشان می‌دهند فرایندهای دگرگونی در ارتباط با فرایند بسته‌شدن پالئوتتیس رخداد دست کم دو فاز دگرگونی ناحیه‌ای در منطقه را به‌دنبال داشته است که یکی از آنها در پی فرورانش پوستة اقیانوسی پالئوتتیس در کربونیفر و پیش از نفوذ گرانیت چاه‌زرد رخ داده است (دگرگونی M1). سپس پس از نفوذ گرانیت چاه‌زرد درون دگرگونه‌ها، دگرگونی دیگری در پی برخورد قاره‌ای رخ داده است (دگرریختی/دگرگونی M2) که این گرانیت را به متاگرانیت تبدیل کرده است. از شواهد فاز دوم دگرریختی/دگرگونی، پیدایش زیردانه و بازتبلور GBM در کوارتزها، پیدایش میرمکیت، پرتیت‌شعله‌ای و بالجینگ در حاشیة فلدسپارها و تبلور گارنت‌های دگرگونی فشار بالا و همزمان با زمین‌ساخت است که با رخداد یک دگرریختی در شرایط فشار بالا و دمای نزدیک به 600 درجة سانتیگراد همخوانی دارد و گویای شرایط دگرگونی ناحیه‌ای در مناطق برخوردی و بسته‌شدن پوستة اقیانوسی پالئوتتیس در شمال بلوک یزد است. افزون بر این، ویژگی‌های زمین‌شیمیایی کانی‌ها (مانند خاستگاه ماگماییِ گارنت‌های شکل‌دار) و مقدار کم δ18O در گرانیت خاور جندق (9/10 ‰) می‌تواند گویای پیدایش مذاب گرانیت چاه‌زرد در پی ذوب اندک بخش‌های فلسیک تختة فرورنده با کمترین آلایش با گوشته در هنگام صعود باشد.

https://ijp.ui.ac.ir/article_29011_eaef2f2bf6ea85dcb718fade064fb5d0.pdf

دانشگاه اصفهان پترولوژی 2228-5210 15 3 2024 09 22 Petrography and geochemistry of volcanic rocks in the Siahouki copper-gold deposit: An example of deposits with shoshonitic host rock in the north of Bam سنگ‌نگاری و زمین‌شیمی سنگ‌های آتشفشانی در محدودة کانسار مس- طلای سیاهوکی: نمونه‌ای از کانسارهای همراه با سنگ میزبان شوشونیتی در شمال بم 89 112 28825 10.22108/ijp.2024.141708.1335 FA علی شهابی نژاد دانشجوی دکتری، گروه زمین‌شناسی اقتصادی، دانشگاه تربیت مدرس، تهران، ایران حسینعلی تاج الدین استادیار، گروه زمین‌شناسی اقتصادی، دانشگاه تربیت مدرس، تهران، ایران مجید قادری استاد، گروه زمین‌شناسی اقتصادی، دانشگاه تربیت مدرس، تهران، ایران Journal Article 2024 06 02 Introduction Today, alkaline rocks are a more important perspective for the largest gold deposits relative to normal calc-alkaline andesites (Müller and Groves, 1993; Sillitoe 1993, 1997, 2002). Specifically, four of the nine largest epithermal gold-silver deposits and four of the ten largest porphyry copper-gold deposits are associated with high-K calc-alkaline and shoshonitic rocks (Sillitoe, 1997, 2002). The high-K igneous rocks only comprise between 5 and 10 vol.% of volcanic arc rocks and are associated with 40% of the largest epithermal and porphyry deposits, indicating their importance for mineral exploration (Müller and Groves, 2019). The Siahouki Cu-Au deposit is located 50 km north of Bam, in the southern part of the Urumieh-Dokhtar magmatic belt of Iran. Considering the potential of shoshonitic volcanic rocks as suitable host rocks for epithermal Au-Cu deposits and also the vastness of the rocks in the area, the petrography, and geochemistry of volcanic rocks in the Siahouki Cu-Au deposit is chosen as the subject of the present research. It is hoped that the study of changes in the Cenozoic volcanism from the Siahouki area can reveal part of the geodynamic and subsequently metallogenic development in this part of Iran. Research method Field investigations including the preparation of a 1:5000 geological map (Figure 3) as well as collection of rock samples. were performed for this study. At this stage, over 50 specimens were taken, of which 25 samples were selected for preparation of thin sections. Using XRF and ICP-MS techniques, the abundance of major oxides, minor, and trace were determined on 22 representative samples. All the samples were then crushed in a jaw crusher in sizes smaller than 5 mm and were then sent to the laboratories. The analysis of major oxides was carried out by XRF at the Geology Department of Tarbiat Modares University and the analysis of major, minor, and trace elements was performed using ICP-MS at the laboratory of Zarazma Minerals Studies Company. Excel, Minpet, and GCDkit 6.2 software were used to process and analyze the data obtained from the geochemical analyses of the major oxides, minor, and trace elements (Table 1) and drawing diagrams as well. Regional Geology The Siahouki deposit located in the Urumieh-Dokhtar Magmatic Belt of Iran (Eftekharnejad et al., 1993), is mainly covered by Eocene volcano-sedimentary rocks and Quaternary alluvium, based on the 1:100,000 Bam geological map. Ev2d unit: includes dacitic lavas, which are partly associated with rhyolitic and rarely andesitic lavas. The unit locally has undergone chlorite alteration. In the places where the argillic alteration is intense, the lavas are light gray to white, and appear cream to light brown in satellite images. The phenocrysts of the unit are mainly replaced by sericite or opaque minerals. Unit (d) consists of banded-welded tuff associated with Eocene dacitic lava and well-layered sediments including conglomerate, sandstone, and siltstone. Unit (t) is also mainly composed of dacite and partly associated with rhyolitic to andesitic lavas, tuff, and ash intercalations. The Eocene volcano-sedimentary units are surrounded by Quaternary alluvial fans (Qf1 and Qf2). These units are cut by younger faults. Alteration and Mineralization Based on field observations along with drilling core data, Cu-Au mineralization in the Siahouki area occurred as quartz and carbonate veins with stockwork and breccia textures, accompanied by silicic, carbonate, and argillic alteration types. The mineralization is exposed along NW-SE structures in the dacitic crystal tuff (Ed) and andesitic lithic tuff (Elt) units, as ore zones up to 200m length and 0.1-2m (average 1 meter) thickness. Field and microscopic studies indicate that ore mineralization is controlled by silicic, carbonate, argillic, and propylitic alteration features. Silicic and carbonate are the most important types of alteration associated with ore (sulfide)-bearing veins. The hypogene ore minerals formed with the quartz and carbonate veins including chalcopyrite, tetrahedrite, bornite, pyrite, and native gold, respectively. During supergene processes, oxidation, and decomposition of sulfide minerals gave rise to the formation of malachite, azurite, chalcocite, and iron oxide-hydroxides as well. Discussion Based on the chemical analytical results of the host rock (Ed unit) in the Siahouki area, the composition of Ed unit plots on the dacite and rhyolite domains (i.e., 61.17 to 76.28 wt.% SiO2) (Table 1). The samples are characterized by the high Al2O3 contents (0.9 to 17.33 wt.%), very high K2O (˃ 4.26 wt.%), and a high ratio of K2O/Na2O, consistent with the chemical characteristics of typical shoshonitic rocks (Morrison, 1980). The studied samples show negative Ta anomalies, and low Nb/Ti ratios, as well as high contents of Al2O3 and P2O5 and the high LILE/HFSE ratios. Also, enrichment in Pb can be related to crustal contamination. The formation of potassic magmatism took place with the release of fluids from the subducted Neo-Tethyan crust, the metasomatism of the lithospheric mantle, and the subsequent melting of the metasomatized mantle, which is the result of an extension phase and fault systems in the region, the parent shoshonitic magma rose to the earth's surface. Conclusion The Eocene volcanic units at Siahouki are mainly composed of lavas and tuffs with an acidic to intermediate (rhyolite, dacite, and andesite) composition associated with intercalations of intermediate to basic (trachy-andesite, basaltic trachy-andesite and basaltic andesite) lavas. The chemical features of the host rocks (Ed unit) at the Siahouki deposit, which are dacite and rhyolite in composition, are comparable with typical shoshonitic rocks. Other geochemical characteristics of the volcanic-hosted Cu-Au mineralization in the Siahouki deposit (including low Nb/Ti ratios, negative Ta anomalies, and the high contents of Al2O3, P2O5, and LILE/HFSE ratios) suggest that the deposit generated in a continental volcanic arc environment and display close genetic relationship with shoshonitic composition. کانسار مس- طلای سیاهوکی در 50 کیلومتری شمال بم و در بخش جنوبی کمربند ماگمایی ارومیه- دختر جای گرفته است. بخش بزرگی از گسترة سیاهوکی از سنگ‌های آتشفشانی ائوسن و نهشته‌های کواترنری پوشیده شده است. واحدهای آتشفشانی ائوسن بیشتر با گدازه‌ها و توف‌های با ترکیب اسیدی تا حد واسط (ریولیت، داسیت و آندزیت) همراه با میان‌لایه‌هایی از گدازه‌های با ترکیب حد واسط تا بازیک (تراکی‌آندزیت، تراکی‌آندزیت بازالتی و آندزیت‌بازالتی) فراگرفته شده است. کانی‌سازی به‌صورت رگه‌- رگچه‌های کوارتز و کربنات در واحدهای کریستال‌توف داسیتی و لیتیک‌توف ‌آندزیتی رخ داده است. بر پایة داده‌های تجزیة شیمیایی، مقدار K2O (بیش از 26/4 درصدوزنی) و نسبت K2O/Na2O (بیشتر از 2) در نمونه‌های سنگ‌های آتشفشانی بالاست. همچنین، داده‌های تجزیة نمونه‌ها گویای نسبت کم Nb/Ti و ناهنجاری منفی عنصر Ti و نیز مقدار بالای نسبت‌هایK2O، Al2O3، P2O5 و LILE/HFSE هستند. ویژگی‌های زمین‌شیمیایی واحدهای آتشفشانی میزبان کانه‌زایی مس- طلا در کانسار سیاهوکی نشان می‌دهد این کانسار در یک محیط کمان آتشفشانی قاره‌ای پدید آمده است و با سنگ‌های با سرشت شوشونیتی ارتباط زایشی نزدیکی نشان می‌دهند.

https://ijp.ui.ac.ir/article_28825_1d8ea0a862b5d6f39603c5b3c95283cd.pdf

دانشگاه اصفهان پترولوژی 2228-5210 15 3 2024 09 22 Mineral chemistry, Geochemistry and petrogenesis of volcanic rocks in the Shahvarogh area (West of Tafresh, Markazi Province) شیمی ‌کانی، زمین‌شیمی و سنگ‌زایی سنگ‌های آتشفشانی ناحیة شاهواروق (باختر تفرش، استان مرکزی) 113 137 29051 10.22108/ijp.2024.142612.1341 FA سیدوحید شاهرخی دانشیار، گروه زمین‌شناسی، واحد خرم‌آباد، دانشگاه آزاد اسلامی، خرم‌آباد، ایران Journal Article 2024 08 27 Introduction The Urmia-Dokhtar Magmatic (volcanic and plutonic) Arc (UDMA) with 2000 Km length in Iran is a small section of the Alpine-Himalayan orogenic belt (Glennie, 2000; Alavi, 2004; Ilbeyli, 2004). The studied area is located in the northeast of Ashtian and composed of two area of Feshk and Master. These areas are situated at 49°44' and 49°55' longitude and 34°31' and 34°44' latitude. Based on the structural zone, this area is a small part of UDMA (Hajian, 1970). Wrinkles and big faults mechanisms such as Tafresh, Talkhab, and Tabarteh have been effective in the formation and morphology of this area that particularly control the sedimentary basins and volcanic processes via the approximate procedure of northwest-southeast. Geology Rock outcrops in the study zones are associated with the Mesozoic and Cenozoic Eras with the oldest ones made of carbonate rocks belonging to the Middle Triassic. The first group is attributed to Eocene, mainly includes acidic tuffs to gray basic, tuffs containing the crystal glass pieces and trachyte lava, trachyandesite and dacitic- rhyodacite types in the form of a semi-dense, gray dark to bright pink dikes and dark lavas from andesites- trachyandesite, quartz latite andesite and basaltic andesite. The Eocene rocks are divided into six units (Lithozone E1 to E6) in this zone consisting of E1 (conglomerate, marl, and sandstone), E2 (ignimbrite, tuff, and nummulite-bearing sandy limestone), E3 (green rhyolitic to dacitic tuff accompanied by marl, shale, sandstone, and limestone), E4 (red to dark brown tuff and dark lava), E5 (green tuff, sedimentary layers, and rhyolite), E6 (basalt, andesite, and dark tuff interlayered with nummulitic limestone) (Hajian, 2001). Sampling and Analytical Techniques The survey was conducted by selecting the proper locations and taking 300 samples. They were exported to the Geological Survey of Iran (GSI) for whole rock chemical analysis with ICP-MS and XRF methods. The microprobe analyses were conducted by Cameca SX100 microprobe (France) with carbon coating at the Iranian Mineral Processing Research Center on 10 polished sections at the Iran Minerals Processing Research Center after detailed petrography studies. Discussion The microscopic study of samples reveals that the rhyolite, dacite, andesite, trachy-andesite and andesi-basalt rocks dominantly have porphyritic, microlite porphyritic and microlite glomeroporphyritic textures. In the dacite rocks, plagioclases have oscillatory zoning. If the magmatic chamber is attacked by the basic magma while cooling the dacite melts, first, the plagioclase crystals melt partially and then become recrystallized. Therefore, these crystals can adsorb dusty textures (Gills, 1981). Amphibole phenocrysts with 3 to 5 Vol.% reveal the effects of burns and decay in most samples of dacite, trachy-andesite, andesi-basalt, and especially the andesite. Amphiboles in the form of inclusion in the plagioclase, are almost anhedral and have a green-blue multiplicity which can represent their sodic composition (Tabatabai Manesh et al. 2010). Pyroxene is another detectable mineral in andesite and andesibasalt rocks. Olivine crystals are observed in approximately 5 Vol% in basaltic andesitic rocks, damaged completely by the decomposition pressure with only a small piece remaining intact. In some thin sections of the dacite rocks, quartz with 3-5% modal frequency is observed with anhedral and neomorph margins in many cases. Geochemistry According to the TAS and AFM Diagram (Le Bas et al., 1986; Irvine and Baragar, 1971), as to lithology combinations, where: 1) the samples vary within dacite to andesite types in the Shahvaroogh and Sadabad area; 2) from trachy-andesite, trachy-basalt, basaltic andesite, andesite and dacite types in Feshk area; 3) from rhyolite, dacite and basaltic andesite composition in Kordabad area. Conveying the obtained results from samples analysis to A/NK to A/CNK, Ti/100-Zr-Y.3, Ti/100-Zr-Sr/2, Ti–Zr (Pearce and Can, 1973), and Nb/Th on Nb (Boztug et al., 2006) and Hf/3-Th-Nb/16 diagram (Wood, 1980; Maniar and Piccolo, 1992), based on Al value reveals that most samples have a meta-alumina nature while others possess per-aluminus affinity. According to many researchers, enrichment of LILE elements (e.g., K, Rb, Sr, Ba, Th,) and LREE and the increase in negative anomaly to great amounts of elements including Ti, Eu, Nb, and HREE (Yb) contribute to the magma contamination by the upper crust during the magmatic evolutions or the presence of intrusive compounds such as the fluids or melts obtained from intrusive sediments in addition to adaptation to the dominant characteristics on the beneath shell (Temel et al., 1998; Kurkcuoglu, 2010). According to the same researchers, in normalized spider figures, the depletion of elements from left to right of the figure indicate that the significant features of faulting zones and LREEs enrichment (between 10-100 times more) in calc-alkaline series are normal. In the Ab-An-Or diagram (Deer et al. 1992) the plagioclase in the trachybasalt and andesibasalt samples lies within the labradorite to bytownite range (only one case of anorthite), in andesitic and trachyandesitic type is oligoclase to andesine, and in dacite- rhyodacite and rhyolite samples are of albite type in Ab-An-Or chart. Based on the Wo-En-Fs ternary plot (Morimoto et al., 1988), all pyroxenes are of augite type. Conclusion The studied volcanic rocks are of basalt andesite types. According to petrographic studies and microprobe analysis, the plagioclase minerals include albite and oligoclase in dacite, and rhyodacite, and rhyolite rocks, oligoclase-andesine in the trachy-andesite and andesite rocks, bytownite-labradorite to anorthite in the trachy-basalt and andesite basalt rocks, and also clinopyroxene (augite and clinoenstatite), amphibole (hornblende and oxihornblende), quartz, biotite, apatite and opaque minerals. The geochemical and petrological results indicate that the source magma of these rocks is a combination similar to the melts derived from the enriched mantle with a fractional 10-20% melting degree of a spinel lherzolite source to garnet-spinel lherzolite. The fluids released from the subducted oceanic slab were effective in the mantle metasomatism. The appearance of the rocks in this area with the volcanism related to the subduction of Neo-Tethys oceanic crust under Central Iran microcontinent. ناحیة شاهواروق در باختر شهرستان تفرش و در شمال استان مرکزی جای گرفته است و بخشی از پهنة‌ ماگمایی ارومیه-‌دختر (UDMA) به‌شمار می‌رود. این ناحیه دربردارندة سنگ‌های آتشفشانیِ تراکی‌بازالت، آندزی‌بازالت، آندزیت، تراکی‌‌آندزیت، داسیت، ریولیت، ریوداسیت، ایگنمبریت، توفیت و توف به سن ائوسن میانی و بالایی است. بافت بیشتر این سنگ‌ها پورفیری، میکرولیتی- پورفیری و میکرولیتی و گاهی نیز غربالی است. کانی‌های سازندة این سنگ‌ها، پلاژیوکلاز، آمفیبول، کلینوپیروکسن و گاهی نیز الیوین و کوارتز هستند. بر پایة داد‌ه‌های شیمی‌کانی، پلاژیوکلازها در تراکی‌‌بازالت و آندزی‌بازالت در گسترة لابرادوریت تا بیتونیت، در آندزیت و تراکی‌‌آندزیت در گسترة الیگوکلاز تا آندزین و در داسیت، ریوداسیت و ریولیت در گسترة آلبیت تا الیگوکلاز جای می‌گیرند. کلینوپیروکسن‌ها بیشتر از نوع اوژیت هستند و شمار کمی نیز ترکیب کلینوانستاتیت نشان می‌دهند. آمفیبول نیز از نوع هورنبلند است. در مقاطع نازک، شواهد آلایش ماگمایی همراه با منطقه‌بندی نوسانی و خوردگی در پلاژیوکلاز شناسایی می‌شود. کنارة سوخته در اطراف آمفیبول‌ها نشان‌دهندة رخداد واکنش‌های اکسایش و تعادل‌نداشتن این کانی در محیط‌های آبدار و پر دماست. داده‌های زمین‌شیمی سنگ ‌کل نشان‌دهندة سرشت متاآلومینوس وکالک‌آلکالن ماگمای مادر سازندة این سنگ‌هاست. ماگمای مادر این سنگ‌ها چه‌بسا از گوشتة دگرنهادشده با درجة ذوب 10% تا 20% اسپینل لرزولیت تا گارنت ‌اسپینل لرزولیت پدید آمده است. این ماگما در مسیر حرکت و هنگام فوران به مقدار کم با پوستة قاره‌ای آلایش یافته است. از دیدگاه تکتونوماگمایی، ماگمای سازنده در پهنة فرورانش پدید آمده ‌است.

https://ijp.ui.ac.ir/article_29051_5b6fcfa79f2c5e6314a277fec05d9949.pdf