دانشگاه فردوسی مشهد زمین شناسی اقتصادی 2008-7306 18 2 2026 08 23 Assessment of Gold Mineralization Potential along the Khonsar–Aligudarz belt, with Emphasis on the Darreh Sari Area, Using Factor Analysis and Geological Evidence ارزیابی پتانسیل کانه ­زایی طلا در محور خوانسار- الیگودرز با تأکید بر منطقه دره ­ساری، با استفاده از تحلیل عاملی و شواهد زمین‌ شناسی 173 197 48840 10.22067/econg.2026.1182 FA مینا شاهین دانشجوی دکتری، گروه زمین‌شناسی، دانشکده علوم، دانشگاه اصفهان، اصفهان، ایران 0009-0000-0379-9805 زهرا اعلمی نیا دانشیار، گروه زمین شناسی، دانشکده علوم، دانشگاه فردوسی مشهد، مشهد، ایران 0000-0002-0018-2428 زهره حسین زاده استادیار، گروه مهندسی معدن، دانشکده مهندسی معدن و مواد، دانشگاه صنعتی همدان، همدان، ایران 0000-0002-8476-4440 سید محسن طباطبایی منش استاد، گروه زمینشناسی، دانشکده علوم، دانشگاه اصفهان، اصفهان، ایران 0000-0003-4050-5073 پوریا محمودی دکتری، شرکت تهیه و تولید مواد معدنی ایران (ایمپاسکو)، تهران، ایران Journal Article 2026 07 28 Assessment of gold mineralization potential in metamorphic terrains requires the application of effective analytical approaches because geochemical patterns are simultaneously influenced by lithological variability, hydrothermal alteration, and structural complexity. In this study, the gold mineralization potential along the Khonsar-Aligudarz belt was evaluated by integrating factor analysis with geological evidence. For this purpose, stream-sediment data from the Golpayegan and Aligudarz 1:100000 geochemical sheets were processed, and inter-element relationships were investigated. The results indicate that factor analysis successfully separated the component related to gold mineralization from the regional lithological background and delineated areas with the highest mineralization potential. Validation of the results through field investigations, petrographic studies, and mineralogical examinations in the Darreh Sari area confirmed the presence of NW-SE trending quartz–hematite–bearing vein-veinlets containing pyrite, pyrrhotite, arsenopyrite, marcasite, chalcopyrite, sphalerite, and galena, as well as iron-, manganese-, and copper-oxide minerals, including hematite, goethite, and, less commonly, magnetite, pyrolusite, and malachite, within Triassic–Jurassic schists and metapelites. The close correspondence between the geochemical anomalies and shear zones and quartz veins indicates that these structures played a major role in channeling mineralizing fluids and concentrating gold. The results of this study indicate that integrating factor analysis with geological information provides an effective approach for reducing uncertainty in regional exploration and prioritizing gold exploration targets in the central Sanandaj–Sirjan Zone and other comparable metamorphic environments.IntroductionGold, as one of the most important strategic and economic metals, forms within a wide range of hydrothermal and orogenic systems, and delineating prospective zones for its occurrence remains a central objective of mineral exploration. In the central Sanandaj–Sirjan Zone, between Khonsar and Aligudarz, several gold occurrences (e.g., Darreh Sari, Hasan Abad, Reza Abad, Hossein Abad, Koucheri, and Sefidsang) have been documented within Triassic–Jurassic schists and metapelites, typically as quartz vein-veinlets with iron and base-metal sulfides and associated silicification, chloritization, carbonatization, and oxidation. Structural control by brittle–ductile shear zones, combined with hydrothermal fluid–rock interaction, has played a fundamental role in concentrating gold and base metals in this belt. Despite reasonable knowledge of these occurrences' geology and mineralogy, regional evaluation of geochemical dispersion patterns remains challenging, since differential element behavior during weathering and transport produces complex, overlapping anomalies that single-element interpretation cannot reliably resolve.Stream sediment geochemistry is among the most effective, economical regional exploration methods for detecting concealed mineralization, though its performance depends heavily on data processing. Conventional univariate threshold methods generally fail to reveal complex inter-element relationships or separate signals from different mineralizing systems, whereas multivariate statistics, particularly factor analysis, overcome this limitation by extracting independent geochemical factors and hidden correlations, distinguishing gold-related components from lithological background or polymetallic systems and improving the accuracy of potential maps. Within this framework, the Darreh Sari area, southwest of Golpayegan and southeast of Aligudarz, was delineated as a gold anomaly from stream sediment data; subsequent field work confirmed quartz–hematite veins- veinlets within Triassic–Jurassic schists accompanied by iron and base-metal sulfides, indicating a gold-bearing hydrothermal system. This study integrates stream sediment geochemistry, factor analysis, and field, petrographic, and mineragraphic evidence to evaluate gold potential along the Khonsar–Aligudarz axis, providing a practical framework for targeted exploration in comparable metamorphic terrains. Geological settingThe study area lies in the central Sanandaj–Sirjan metamorphic-structural zone, one of Iran's principal metamorphic-magmatic and metallogenic belts, whose evolution is generally attributed to Paleo-Tethys closure and prolonged Neo-Tethyan subduction beneath Central Iran from the Late Triassic to the Cenozoic, accompanied by magmatism, regional metamorphism, and polyphase deformation; an alternative model instead links part of the Mesozoic magmatism to intracontinental rifting. The belt mainly comprises Mesozoic sedimentary–volcanic sequences metamorphosed under greenschist- to amphibolite-facies conditions, producing slate, phyllite, quartzite, schist, amphibolite, and gneiss. In the central sector, Triassic–Jurassic phyllite–schist sequences are cut by numerous shear zones and faults that, with hydrothermal circulation and quartz veining, principally control mineralization.Materials and methodsGeochemical data from 947 stream sediment samples covering ~1,419 km2 across the Golpayegan and Aligudarz 1:100000 sheets (Mohajjel and Eftekhar Nezhad, 1992; Soheili et al., 1992), previously analyzed by inductively coupled plasma spectrometry and archived by the Geological Survey and Mineral Exploration Organization of Iran, were used. Concentrations of Cu, Pb, Zn, Ba, B, Co, Cr, Mn, Ni, Sc, Sr, V, and Y were evaluated via descriptive statistics, frequency and box plots, and factor analysis with varimax rotation on standardized data to extract mineralization-related factors and construct factor-score maps. The previously undocumented Darreh Sari anomaly was investigated over two field campaigns documenting mineralized outcrops, and alteration zones, sampled for petrographic and mineragraphic study; five rock-chip samples from two gold-bearing veins were analyzed for gold grade by Fire Assay. ResultsStream Sediment Geochemistry Results Stream sediment concentrations show wide ranges reflecting catchment-scale geochemical heterogeneity. Co and Ni display the most uniform distributions, consistent with lithological control, whereas B (CV = 73.4%) and Mn (CV = 94.1%) show the greatest dispersion, reflecting hydrothermal alteration or oxide concentration; Pb shows the highest variability among base metals (CV = 59.3%), suggesting local sulfide enrichment. Factor analysis extracted six factors: lithological (Sc–Y–V), mafic (Ni–Cr–Co), mineralization (Pb–Zn–Mn), alteration (B–Ba), carbonate (Sr), and magmatic-hydrothermal (Cu). The mineralization factor-score map shows pronounced anomalies at the Reza Abad, Hasan Abad, and Takht-e Khosrow occurrences, plus a distinct NW–SE-trending anomaly at Darreh Sari matching the vein orientation; all anomalies are confined to the Triassic–Jurassic greenschist unit, confirming its role in mineralization.At Darreh Sari, local geology comprises Precambrian mica schists with metarhyolite intercalations, Triassic–Jurassic units (marble, black shale, slate, phyllite, schist), granodioritic intrusions, and Quaternary deposits. The intensely fractured, thrust-bounded metamorphic units favored quartz-vein emplacement, while carbonaceous black shales likely supplied sulfur and gold. Gold occurs mainly as two NW–SE-trending silicic veins (~990 m long, ~2 m wide) parallel to host-rock schistosity, locally cut by younger veinlets indicating post-mineralization reactivation. Fire Assay of five samples yielded gold grades of 87, 1051, 2591, and 5256 mg/t east to west along the main vein and 557 mg/t in a subsidiary vein, with the highest grades in the west matching the strongest anomaly and confirming economic mineralization. Mineragraphic study shows abundant multi-generation pyrite and pyrrhotite, accessory arsenopyrite, marcasite, chalcopyrite, sphalerite, and galena as intergrowths and cavity fillings, subordinate early-stage magnetite, and colloform marcasite, consistent with a hydrothermal quartz-vein system corroborating the geochemical model.DiscussionGold mineralization at Darreh Sari developed within a Sanandaj–Sirjan segment shaped by Neo-Tethyan convergence, regional metamorphism, and crustal-scale shear zones. Factor analysis effectively separated lithological background (Factors 1, 2) from mineralization-related components (Factors 3, 6), which form discrete anomalies independent of lithological boundaries and spatially linked to alteration, confirming the superiority of multivariate over single-element interpretation in structurally complex terrains. The close correspondence between anomalies, shear zones, and quartz veins indicates that brittle–ductile structures were the primary conduits for mineralizing fluids, consistent with structural controls documented for the Muteh gold belt and other orogenic systems of the zone. The paragenetic sequence, pyrite and pyrrhotite followed by base-metal sulfides, reflects progressive evolution of a multistage hydrothermal system consistent with orogenic gold models. Carbon-rich host rocks likely contributed sulfur, CO2, and metals through devolatilization, consistent with models in which organic matter scavenges, transports, and helps precipitate gold via fluid reduction. Surface hematitic staining likely reflects supergene oxidation, yet the coherent anomalies indicate the primary hydrothermal signal survived weathering. These results confirm that multivariate analysis of stream sediment data reveals hydrothermal signals in complex terrains, and that integrating it with structural and remote-sensing data effectively reduces exploration uncertainty and prioritizes drilling targets. ConclusionThis study demonstrates that factor analysis of stream sediment geochemical data, integrated with geological and mineragraphic evidence, effectively identifies gold-related anomalies in the Darreh Sari area and along the Khonsar–Aligudarz belt. Separating lithological components from hydrothermal signals enabled recognition of genuine mineralization-related anomalies, whose strong correspondence with NW–SE-trending shear zones, quartz veins, and Triassic–Jurassic metamorphic units confirm the key role of structural controls in channeling fluids and concentrating gold. Consistency between geochemical and field/mineragraphic observations validates a structurally controlled hydrothermal model, offering an efficient framework for prioritizing exploration targets and reducing uncertainty in early-stage gold exploration across comparable settings of the Sanandaj–Sirjan Zone. ارزیابی پتانسیل کانه‌زایی طلا در مناطق دگرگونی به دلیل تأثیر هم‌زمان تنوع سنگ‌شناسی، دگرسانی‌های گرمابی و پیچیدگی‌های ساختاری بر الگوهای زمین‌شیمیایی، نیازمند به‌کارگیری روش‌های تحلیلی کارآمد است. در این پژوهش، پتانسیل کانه‌زایی طلا در محور خوانسار- الیگودرز با تلفیق تحلیل عاملی و شواهد زمین‌شناسی مورد ارزیابی قرار‌گرفته است. برای این منظور، داده‌های رسوب آبراهه‌ا­ی مربوط به برگه‌های زمین‌شیمیایی ۱:۱۰۰۰۰۰ گلپایگان و الیگودرز پردازش‌شده و روابط بین عناصر مورد بررسی قرار‌گرفته است. نتایج نشان می‌دهد که تحلیل عاملی توانسته است مؤلفه‌ مرتبط با کانه‌زایی طلا را از زمینه‌ی سنگ‌شناسی منطقه به‌ خوبی تفکیک‌کرده و پهنه‌های دارای بیشترین پتانسیل کانه‌زایی را مشخص‌کند. اعتبارسنجی نتایج از طریق بررسی‌های صحرایی، سنگ‌نگاری و کانی‌شناسی در محدوده‌ دره‌ساری، وجود رگه- رگچه‌های کوارتز- هماتیت‌دار با روند شمال‌غربی- جنوب‌شرقی، حاوی کانی‌های پیریت، پیروتیت، آرسنوپیریت، مارکازیت، کالکوپیریت، اسفالریت و گالن و همچنین کانی‌های اکسیدی آهن، منگنز و مس شامل هماتیت، گوتیت و به ‌ندرت مگنتیت، پیرولوزیت و مالاکیت را در شیست‌ها و متاپلیت‌های تریاس- ژوراسیک تأیید می‌کند. انطباق مناسب بی‌هنجاری‌های زمین‌شیمیایی با پهنه‌های برشی و رگه‌های کوارتزی نشان می‌دهد که این ساختارها نقش اصلی را در هدایت سیالات کانه‌زا و تمرکز طلا ایفا کرده‌اند. نتایج این پژوهش بیانگر آن است که تلفیق تحلیل عاملی با اطلاعات زمین‌شناسی، رویکردی مؤثر برای کاهش عدم ‌قطعیت در اکتشاف ناحیه‌ای و اولویت‌بندی اهداف اکتشافی طلا در بخش میانی پهنه‌ی سنندج- سیرجان و سایر محیط‌های دگرگونی مشابه را فراهم می‌آورد. https://econg.um.ac.ir/article_48840_dcda4faf1ee68fd824f9bdefc41b8e19.pdf