دانشگاه اصفهان پترولوژی 2228-5210 16 4 2025 12 22 Petrology and geochemistry of igneous rocks and their relationship with mineralization in Talahoueieh area, north of Bam, Urumieh-Dokhtar Magmatic Arc سنگ‏‌شناسی و زمین‏‌شیمی سنگ‏‌های آذرین و ارتباط آنها با کانه‏‌زایی در محدودة تلاهوییه، شمال بم، کمان ماگمایی ارومیه- دختر 83 110 30247 10.22108/ijp.2026.147520.1377 FA جلال حسن شاهی دانشجوی دکتری، گروه زمین‌شناسی اقتصادی، دانشگاه تربیت مدرس، تهران، ایران مجید قادری استاد، گروه زمین‌شناسی اقتصادی، دانشگاه تربیت مدرس، تهران، ایران حسینعلی تاج الدین استادیار، گروه زمین‌شناسی اقتصادی، دانشگاه تربیت مدرس، تهران، ایران، Journal Article 2025 11 25 <strong>Introduction</strong> 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. <strong>Research Method</strong> 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. <strong>Regional Geology</strong> 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. <strong>Alteration and Mineralization</strong> 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. <strong>Discussion </strong> 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. <strong>Conclusion</strong> 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. محدودة تلاهوییه در ۲۰ کیلومتری شمال بم در جنوب‏‌خاوری ایران، شامل واحدهای متنوعی از سنگ‏‌های آتشفشانی- رسوبی، آذرین آتشفشانی و درونی است که در محیط فرورانش پوستة اقیانوسی و کمان ماگمایی پدید آمده‏‌اند. سنگ‏‌های رسوبی قدیمی‏‌تر شامل شیل، توف و کنگلومرا هستند که در زیر واحدهای آتشفشانی جای دارند و واحدهای آذرآواری و آتشفشانی داسیتی- آندزیتی با رنگ‏‌های ارغوانی تا خاکستری تیره در سطح محدوده گسترده‏‌ شده‌اند. توده‏‌های آذرین درونی گرانیتی کوچک نیز در جنوب محدوده دیده می‌شوند که در برخی بخش‌ها به کانه‏‌زایی اسکارنی انجامیده‏‌اند. سنگ‏‌های آذرین بیشتر از نوع کالک‏‌آلکالن تا شوشونیتی با ترکیب پتاسیم متوسط تا بالا هستند که گویای فرایندهای ماگمایی شامل جدایش بلوری، ذوب ‌بخشی و آلایش پوسته‏‌ای هستند. الگوهای عنصرهای خاکی کمیاب با غنی‏‌شدگی LREE، تهی‏‌شدگی HREE و آنومالی منفی Eu با محیط کمانی و سامانه‏‌های پورفیری- اپی‏‌ترمال همخوانی دارند. در این محدوده، دگرسانی‏‌ها شامل پهنه‏‌های گستردة آرژیلیک، سیلیسی و کلریتی هستند که نقش مهمی در تمرکز فلزهای چندگانه (Cu-Pb-Zn-Ag) به‏‌صورت رگه- رگچه‏‌ای داشته‏‌اند. کانه‏‌زایی رگه‏‌ای با کنترل ساختاری از راه گسل‏‌های راستالغز راستگرد و حضور سیالات گرمابی اسیدی همراه است که در توف‏‌های آذرآواری و کمتر در آندزیت‏‌ها کانه‏‌زایی دیده می‏‌شود. ترکیب کانی‏‌شناسی کانه‏‌ها شامل کالکوپیریت، بورنیت، مالاکیت، آزوریت، گالن و اسفالریت است و نشان‏‌دهندة سامانه گرمابی با دمای متوسط تا پایین است. این مجموعه شواهد زمین‏‌شیمیایی، کانی‏‌شناسی و ساختاری نه‌تنها سرشت زمین‌ساختی محدودة تلاهوییه را روشن می‏‌سازد، بلکه بررسی این سامانه می‏‌تواند راهنمای ارزشمندی برای گسترش اکتشافات معدنی و ارزیابی منابع فلزات چندگانه و ذخایر پورفیری- اپی‏‌ترمال منطقه باشد. https://ijp.ui.ac.ir/article_30247_1e848e3a0e83467043cbb6f61f9b7868.pdf