@article { author = {Karimpour, Mohammad Hassan and Shirdashtzadeh, Nargess and Sadeghi, Martiya}, title = {Granitoids of Sanandaj-Sirjan Zone that are concurrent with Cimmerian Orogeny (178-160 Ma) belong to ilmenite series (S-type): investigation of reason for lacking the porphyry tin mineralization}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {1-28}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.1011}, abstract = {Introduction The granitic rocks are divided into magnetite and ilmenite series (Ishihara 1977), coinciding spatially with the I-type (εNdi0; (87Sr/86Sr)i~0.704-0.706) and S-type granites (εNdi<0; (87Sr/86Sr)i~0.708-0.765), respectively (Takahashi et al., 1980). Most porphyry Sn deposits are associated with ilmenite (S-type) granitoids (Ishihara, 1977; Neiva, 2002). The published concepts on the origin and tectonomagmatic setting of Sanandaj-Sirjan Zone (SaSZ) Jurassic granitoids of 178-160 Ma are (1) metaluminous I-type granites formed in a magmatic arc of an Andean subduction system (Khalaji et al., 2007; Tahmasbi et al., 2010; Ahadnejad et al., 2011; Esna-Ashari et al., 2012), (2) subduction-related extensional basin (Shahbazi et al., 2010), (3) continental crust melting by roll-back of Neo-Tethys oceanic crust (Zhang et al., 2018), and (4) subduction-related S-type granites (Bayati et al., 2017). In this research, the origin and tectonomagmatic setting of Jurassic granitoids (from 178 to 160 Ma) in Sanandaj-Sirjan Zone and the tin mineralization potential are investigated based on the available geological, geophysical and isotopic geochemical data.   Materials and methods We used an integrated collection of published geochemical data (major, trace and rare earth elements of 102 samples), isotopic (e.g., (87Sr/86Sr)I of 50 samples, ƐNdi of 64 samples), geochronological (U-Pb dating of zircons), and geophysical data (airborne magnetic intensity) for the SaSZ granitoids of 178-160 Ma.   Result The SaSz Jurassic granitoids include granite, monzonite, diorite, Syenogranite, tonalite batholiths. The (87Sr/86Sr)I>0.707, N-MORB normalized patterns with enrichment in Low- and High Field Strength Elements (LFSE and HFSE) and depletion in P and Ti contents, chondrite-normalized patterns with flat heavy rare earth elements (HREE) patterns, magnetic susceptibility <10-5x100 (ilmenite series), no alteration, and no Sn, Cu, Pb, and Zn anomalies in whole rock composition of granitoids nor in the associated river sediments, absence of volcanic rocks, and occurrence of metamorphic rocks (slate and schist) during Cimmerian orogeny indicate the SaSZ granitoids are S-type granitoids formed in a continental collision zone.   Discussion Geological, geophysical and geochemical characteristics of granitoids in Sanandaj-Sirjan Zone (such as the absence of volcanic arc and volcanic rocks, continental crust thickening (56-52 km) and the formation of large-scale (batholith) granitoids at depths >4 km, regional metamorphism at ​​green schist facies (and amphibolite) following Cimmerian orogeny, low (Eu/Eu)N (reducing conditions), magnetic susceptibility <100x10-5 (ilmenite series), negative εNdi and (87Sr/86Sr)I >0.707) show that, unlike previous studies, these granitoids are S-type granitoids formed by melting the continental crust in a collisional zone. Therefore, tin mineralization might probably occurred in connection with them. However, there is ample evidence of the absence of tin mineralization by the magma that forms these S-type granitoids, that are including the lack of hydrothermal fluids and consequently mineralization potential (due to the absence of alteration minerals in ASTER satellite images), low content of tin, copper, lead and zinc elements in these granitoids Sanandaj-Sirjan Zone and associated river sediments, (Eu/Eu)N value > 0.2, Rb/Sr <3, low Y (10-75 ppm), Ba > 200 ppm, as well as the geological, geophysical and geochemical similarities to barren S-type (ilmenite series) granitoids in Lut block (in Najmabad, Sorkh kuh to Shah kuh areas) which have formed in a continental collision system during the Cimmerian orogeny.   References Ahadnejad, V., Valizadeh, M., Deevsalar, R. and Rezaei-kahkhaei, M., 2011. Age and geotectonic position of the Malayer granitoids: Implication for plutonism in the Sanandaj-Sirjan Zone, W Iran. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 261(1): 61–75. https://doi.org/10.1127/0077-7749/2011/0149 Bayati, M., Esmaeily, D., Maghdour-mashhour, R., Li, X. and Stern, R.J., 2017. Geochemistry and petrogenesis of Kolah-Ghazi granitoids of Iran: Insights into the Jurassic Sanandaj-Sirjan magmatic arc. Chemie der Erde- Geochemistry, 77(2): 281–302. https://doi.org/10.1016/j.chemer.2017.02.003 Esna-Ashari, A., Tiepolo, M., Valizadeh, M., Hassanzadeh, J. and Sepahi, A., 2012. Geochemistry and zircon U–Pb geochronology of Aligoodarz granitoid complex, Sanandaj-Sirjan Zone, Iran. Journal of Asian Earth Sciences, 43(1): 11–22. https://doi.org/10.1016/j.jseaes.2011.09.001 Ishihara, S., 1977. The Magnetite-series and Ilmenite-series Granitic Rocks. Mining Geology, 27(145): 293–305. https://doi.org/10.11456/shigenchishitsu1951.27.293 Khalaji, A.A., Esmaeily, D. and Valizadeh, M. V., 2007. Petrology and geochemistry of the granitoid complex of Boroujerd, Sanandaj-Sirjan Zone, Western Iran. Journal of Asian Earth Sciences, 29(5-6): 859–877. https://doi.org/10.1016/j.jseaes.2006.06.005 Neiva, A.M.R., 2002. Portuguese granites associated with Sn-W and Au mineralizations. Bulletin of the Geological Society of Finland, 74: 79–101. https://doi.org/10.17741/bgsf/74.1-2.003 Shahbazi, H., Siebel, W., Pourmoafee, M., Ghorbani, M., Sepahi, A.A., Shang, C.K. and Abedini, M.V., 2010. Geochemistry and U – Pb zircon geochronology of the Alvand plutonic complex in Sanandaj – Sirjan Zone (Iran): New evidence for Jurassic magmatism. Journal of Asian Earth Sciences, 39(6): 668–683. https://doi.org/10.1016/j.jseaes.2010.04.014 Takahashi, M., Aramaki, S. and Ishihara, S., 1980. Magnetite-Series/Ilmenite Series vs. I-type/S-type granitoids, Granitic Magmatism and related mineralization. Mining Geology, Special Issue, 8: 13–28. Tahmasbi, Z., Castro, A., Khalili, M., Khalaji, A.A. and De, J., 2010. Petrologic and geochemical constraints on the origin of Astaneh pluton, Zagros. Journal of Asian Earth Sciences, 39(3): 81–96. https://doi.org/10.1016/j.jseaes.2010.03.001 Zheng, W., Mao, J., Zhao, C., Zhang, Z., Xiao, W., Ji, W., Majidifard, M.R., Rezaeian, M., Talebian, M., Xiang, D., Chen, L., Wan, B., Ao, S. and Esmaeili, R., 2018. Geochemistry, zircon U-Pb and Hf isotope for granitoids, NW Sanandaj-Sirjan zone, Iran: Implications for Mesozoic-Cenozoic episodic magmatism during Neo-Tethyan lithospheric subduction. Gondwana Research, 62: 227–245. https://doi.org/10.1016/j.gr.2018.04.002}, keywords = {S-type granitoid,Sn deposit,Cimmerian Orogeny,Sanandaj-Sirjan zone}, title_fa = {گرانیتوئیدهای پهنه سنندج-سیرجان متعلق به سری ایلمینیت (نوع S)، همزاد با کوه‌ زایی سیمیرین (178-160 میلیون سال پیش): بررسی علت عدم تشکیل کانی‌ سازی قلع پورفیری}, abstract_fa = {در این پژوهش، بر اساس داده‌های زمین‌شناسی، زمین‌فیزیکی، زمین‌شیمیایی ایزوتوپی موجود برای گرانیتوئیدهای ژوراسیک (بازه 178-160 میلیون سال پیش) در پهنه سنندج-‌سیرجان1، به بررسی خاستگاه و پهنه تکتونوماگمایی این گرانیتوئیدها و امکان کانی‌سازی قلع در ارتباط با آنها پرداخته می‌شود. ویژگی‌های زمین‌شناسی، زمین‌فیزیکی و زمین‌شیمیایی گرانیتوئیدهای پهنه سنندج-سیرجان (مانند نبود کمان آتشفشانی و سنگ‌های آتشفشانی، ضخیم‌شدگی پوسته قاره‌ای (52 تا 56 کیلومتر) و تشکیل توده‌های گرانیتوئیدی با ابعاد بزرگ (باتولیت) در عمق بیشتر از 4 کیلومتر، پیدایش سنگ‌های دگرگونی و رویداد دگرگونی ناحیه‌ای در حد رخساره شیست سبز (و آمفیبولیت) در پی فرایندهای کوه‌زایی سیمیرین، مقدار (Eu/Eu)N کم (شرایط احیایی)، پذیرفتاری مغناطیسی کمتر از 5-10 x100 (سری ایلمینیت)، εNdiمنفی و (87Sr/86Sr)i بیشتر از 707/0) برخلاف پژوهش‌های پیشین نشان می‌دهند که این گرانیتوئیدها از گرانیتوئیدهای نوع S پدیدآمده در پی ذوب پوسته قاره‌ای در پهنه برخوردی هستند. از این‌رو، وقوع کانی‌سازی قلع در ارتباط با پیدایش آنها محتمل است؛ اما شواهد بسیاری بیانگر نبود کانی‌سازی قلع توسط ماگمای سازنده این گرانیتوئیدهاست که عبارتند از نبود محلول‌های گرمابی و در نتیجه توانایی کانی‌سازی (با توجه به نبود کانی‌های دگرسانی در تصاویر ماهواره ASTER)، فراوانی اندک عنصرهای قلع، مس، سرب و روی در این گرانیتوئیدها و رسوب‌های رودخانه‌ای وابسته به آنها، مقدار (Eu/Eu)N بیشتر از 2/0، Rb/Sr کمتر از 3، Y کم (ppm 10-75)، Ba بیشتر از ppm 200 و شباهت‌های زمین‌شناسی، زمین‌فیزیکی و زمین‌شیمیایی به گرانیتوئیدهای نوع S (سری ایلمینیت) نابارور در بلوک لوت (در مناطق نجم‌آباد، سرخ‌کوه تا شاه‌کوه) که در پهنه برخورد قاره‌ای و در طی کوه‌زایی سیمیرین پدید آمده‌اند.}, keywords_fa = {گرانیتوئید نوع S,کانسار قلع,کو‌ه‌ زایی سیمرین,پهنه سنندج-‌سیرجان}, url = {https://econg.um.ac.ir/article_40213.html}, eprint = {https://econg.um.ac.ir/article_40213_6acaaad454b97210ba50c560c0cb1f78.pdf} } @article { author = {Pezeshki Gharache, Farzaneh and Mousivand, Fardin and Rezaei-Kahkhaei, Mehdi and Fardoost, Farajollah}, title = {Ore facies, mineralogy, alteration, geochemistry and genesis of the Vanakan (Sokan) barite-zinc-lead-copper deposit, north east of Semnan}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {29-55}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.82657}, abstract = {Introduction The Vanakan (Sokan) barite-zinc-lead-copper deposit is located at 23 km northeast of Semnan, in the North Central Iran magmatic belt. It has occurred within the Eocene volcanic-sedimentary sequence. The host rocks of the ores mainly consist of tuff, shale and shaly tuff. Volcanic rocks in the district at the Ahovan region involve both mafic and felsic compositions including basalt, andesite, dacite, rhyolite and tuff. Many studies have been conducted on ore deposits in the Semnan region including Poshteh barite- base metals volcanogenic massive sulfide (VMS) deposit (Ghaffari, 2017), Hamyard (Haji-Bahrami, 2012) and northeast Semnan (e.g., Ghiasvand et al., 2009; Shahri, 2011) iron skarn deposits. Therefore, studying the barite-metal deposits in the Central Iran magmatic belt such as the Vanakan deposit, can provide exploratory keys to discover new reserves, which is one of the main goals of this research study. In this work, study on ore facies,mineralogy, alteration, geochemistry and genesis of the Vanakan barite-zinc-lead-copper deposit are considered.   Materials and methods First, regional and local geology, alteration, ore textures and structures and mineralogy of ore horizons in the Vanakan ore deposit were carefully checked out and studied during field studies. Then, the samples were systematically collected from trenches and open pit of the mine. Mineralogical studies were conducted on 24 thin sections and 8 polished samples in the microscopic laboratory at the Shahrood University of Technology. For geochemical studies, about 16 systematic samples from different ore facies and ore horizons were collected. Then, the samples were analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) method, and a few samples were studied by X-ray diffraction (XRD) method in the Aria Sharif Laboratories Company.   Results The host sequence in the Vanakan deposit involves three units, from bottom to top: Unit1: conglomerate, limestone, sandstone; Unit2: andesitic to dacitic lava-rich, and unit3: acidic tuff-rich. Mineralization as the Vanakan 1 and 2 deposits occurred at top of unit 2 and within unit 3. The entire Vanakan area involves a local syncline with northeast-southwest axial trend, in which the Vanakan 1 and Vanakan 1 deposits are located in the northern and southern limbs of the syncline, respectively. Based on structural,  textural and mineralogical studies, five different ore facies were distinguished  in Vanakan 1, from bottom to: 1) vein-veinlet and breccia: involving barite-pyrite-quartz vein-veinlets, 2) massive sulfide: composed of massive sphalerite, galena, barite, chalcopyrite and pyrite, 3) layered-banded sulfide ore: involving alternations of ore and sericite altered tuff-rich bands, 4) baritic ore: comprising of mainly barite and little sulfides, and 5) banded-exhalative cherty sediments. The ore facies in the Vanakan 2 from bottom to top are 1) barite -(galena)-rich vein-veinlets and 2) banded cherty iron oxide-hydroxides -rich red exhalative sediment. From a mineralogical point of view, the ores in the Vanakn 1 mainly consist of barite, sphalerite, galena, pyrite, chalcopyrite and marcasite accompanied with secondary minerals such as malachite, chrysocolla, smithsonite, cerussite, hematite, limonite, goethite.   Discussion Based on different characteristics of mineralization in the Vanakan district, such as geometry of ore bodies, textures and structures, ore facies, wall rock alterations, mineralogy, metal zonation and geochemical features, the Vanakan deposit can be classified as a bimodal- felsic or Kuroko-type volcanogenic massive sulfide (VMS) deposit, similar to those of the Mount Read volcanic deposits of Tasmanian Australia such as Rosebery (Large, 1992; Large et al., 2001) and Hokuroko basin in Japan (Huston et al., 2011; Ohmoto and Skinner, 1983).   References Ghaffari, G., 2017. Mineralogy, geochemistry and genesis of the Poshteh barite-kaoline-copper deposit, east of Semnan. M.Sc. thesis, Shahrood University of Technology, Shahrood, Iran, 186 pp. (in Persian with English abstract) Ghiasvand, A., Ghaderi, M. and Rashidnejad, N., 2009. Mineralogy, geochemistry and origin of iron deposits in north of Semnan. Geosciences, 18(72): 33–44. https://doi.org/10.22071/GSJ.2010.57133 Haji-Bahrami, M., 2012. Petrography, geochemistry and genesis of the Hamyard iron deposit, northeast of Semnan. M.Sc. Thesis, Damghan University, Damghan, Iran, 175 pp. (in Persian with English abstract). Huston, D.L., Relvas, J.M.R.S., Gemmell, J.B. and Drieberg, S., 2011. The role of granites in volcanic-hosted massive sulphide ore-forming systems: an assessment of magmatic–hydrothermal contributions. Mineralium Deposita, 46(5–6), 473–507. https://doi.org/10.1007/s00126-010-0322-7 Large, R.R., 1992. Australian volcanic-hosted massive sulfide deposits; features, styles, and genetic models. Economic Geology, 87(3): 471–510. https://doi.org/10.2113/gsecongeo.87.3.471 Large, R.R., McPhie, J., Gemmell, J.B., Herrmann, W. and Davidson, G.J., 2001. The spectrum of ore deposit types, volcanic environments, alteration halos, and related exploration vectors in submarine volcanic successions: Some examples from Australia. Economic Geology, 96(5): 913–938. https://doi.org/10.2113/gsecongeo.96.5.913 Ohmoto, H. and Skinner, B.L., 1983. The Kuroko and related volcanogenic massive sulphide deposits: Introduction and summary of new findings. In: H. Ohmoto and B.J. Skinner (Editors), Kuroko and related volcanogenic massive sulphide deposits. Economic Geology, Canada, pp. 1-8. https://doi.org/10.5382/Mono.05.01 Shahri, M., 2011. Investigation of skarnization, metasomatism and related to mineralization in Zartul area (Northeast Semnan). M.Sc. thesis, University of Technology, Shahrood, Iran, 144 pp. (in Persian with English abstract)}, keywords = {Barite- Zinc- lead- copper,Volcanogenic massive sulfide,Kuroko,Vanakan,Sokan,ore facies,Semnan}, title_fa = {رخساره‌های کانسنگ، کانی‌ شناسی، دگرسانی، ژئوشیمی و الگوی تشکیل کانسار باریت- روی-سرب-مس ونکان (سوکان)، شمال شرق سمنان}, abstract_fa = {کانسار باریت-‌روی-‌سرب-‌مس ونکان (سوکان) با سنگ میزبان توف، توف ­شیلی، گدازه آندزیتی و تراکی ­آندزیت به سن ائوسن در شمالی‌ترین بخش از کمربند ماگمایی شمال ایران مرکزی در شمال‌شرق سمنان واقع‌شده است. توالی میزبان از پایین به بالا شامل سه واحد سنگی است: 1) واحد غنی از سنگ‌های رسوبی شامل کنگلومرا، سنگ آهک و ماسه‌سنگ، 2) واحد غنی از گدازه حاوی سنگ ­هایی با ترکیب حدواسط تا اسیدی، آندزیت و تراکی­ آندزیت به همراه میان‌لایه­ هایی از شیل و 3) واحد غنی از توف شامل توف‌های داسیتی، توف ریولیتی و توف­ شیلی. منطقه معدنی ونکان در ناودیسی با روند محوری شمال‌شرقی-جنوب‌غربی قرار دارد. کانه ­زایی در کانسار ونکان به‌صورت سه افق کانه زایی دیده می­ شود. افق اول و اصلی کانه ­زایی که در یال شمال­ غربی ناودیس قرار دارد، شامل کانسار ونکان 1 بوده که از پایین به بالا از پنج رخساره کانه ­دار تشکیل شده است: 1) رخساره رگه-‌رگچه ­ای، 2) کانسنگ سولفید توده ­ای، 3) کانسنگ باریت لایه­ ای، 4) کانسنگ لایه ­ای- نواری سولفیدی و 5) رخساره نواری رسوبی-‌برون‌دمی. کانسار ونکان 2 واقع در یال جنوب­ شرقی دارای رخساره ­های 1) رگه-‌رگچه­ ای و برشی و 2) نواری رسوبی-‌برون‌دمی است. بافت ماده معدنی اغلب شامل رگه-‌رگچه­ ای، توده­ ای، برشی،  نواری-‌لامینه و دانه ­پراکنده است. کانی‌های اولیه و اصلی در ماده معدنی به ترتیب شامل باریت، اسفالریت، گالن، پیریت، کالکوپیریت و مارکاسیت و کانی‌های ثانویه مالاکیت، کریزوکولا، گوتیت، لیمونیت، اسمیت­زونیت و سروزیت هستند. دگرسانی عمده در کانسار ونکان در سنگ دیواره کمرپایین از نوع کلریتی و سریسیتی و به مقدار کمتر اپیدوتی، آرژیلیکی و سیلیسی است. طبق پژوهش‌های انجام‌شده، به‌نظر می­ رسد کانسارهای باریت-‌فلزات ­پایه ونکان بر اساس مقایسه با انواع مختلف کانسارهای سولفید توده ­ای آتشفشان‌زاد، بیشترین شباهت را با کانسارهای نوع کوروکو نشان می­ دهند.}, keywords_fa = {باریت-‌روی-‌سرب-‌مس,سولفید توده ای آتشفشان زاد,کوروکو,ونکان,سوکان,رخساره کانه دار,سمنان}, url = {https://econg.um.ac.ir/article_40226.html}, eprint = {https://econg.um.ac.ir/article_40226_2f2ce056ef2cea94aa41c1763130406f.pdf} } @article { author = {Hosseini, Kiamars and Rajabzadeh, Mohammad Ali}, title = {Mineralogy, Geochemistry, and Fluid Inclusion Microthermometry of Apatite and Rare Earth Element Minerals in the Esfordi Deposit, NE of Bafq, Yazd Province}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {57-84}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.84702}, abstract = {Introduction REE should be evaluated in rocks and minerals due to their behavior in complex geochemical processes leading to their use as tracers in geochemical environments. In addition, the lack of economic concentration of these elements is related to their contribution in rock forming minerals. Thus, high levels of technology and costs are essential for their extraction. However, REE minerals can be formed under special geological conditions. In this regard, the Esfordi iron-phosphate deposit is interesting both economically and scientifically. The present study is aimed at determination of rare earth element mineral types, along with their occurrence in this deposit by using mineralogy, geochemistry, and fluid inclusion microthermometry methods.   Method of study A total of 42 apatite samples were taken from different lithological units and ore-bearing veins. Following petrographic observations, 10 and 6 representative samples were analyzed using SEM and XRD methods in the Iran Minerals Processing Research Center, respectively. Geochemical properties of apatite and rare earth element minerals were determined on 8 samples using LA-ICP-Ms at the University of Tasmania, Australia. Moreover, the same was done for 6 samples using EPMA at the Geo Forschungs Zentrum Telegrafenberg of Potsdam University, Germany. In addition, 12 samples of apatite were considered for evaluating petrography of fluid inclusions. Microthermometry of the fluid inclusions was conducted on two second generation apatite samples associated with massive phosphate mineralization zone and magnetite mineralization zone in the laboratory of the Geological Survey and Mineral Explorations of Iran. Phases changes in fluid inclusions in heating and freezing tests under a Linkam THM600 microscope with TP94 Thermal Controller and LNP Type Cooler mounted on Zeiss microscope, with an accuracy of ±0.5 ˚C was performed. Given that no phase changes were produced in some inclusions (melt inclusions) up to the temperature of 600°C, two samples of apatite were studied using the Linkam TS1400XY microscope in Lithosphere Fluid Research Lab of the Department of Petrology and Geochemistry at Eötvös Loránd University, Budapest, Hungary.   Results Mineralogical studies of apatite in Esfordi revealed the extensive presence of monazite and a lesser amount of xenotime. The results indicate two generations of monazite in this deposit. The first generation is observed as inclusions within the apatites, while the second generation occurs along the fractures of apatites. Monazite inclusions are abundant in the dark phase of host apatites. Based on geochemical data, the second generation of monazite is enriched in La, La/Ce, Nd, and Pr compared to the first generation. Furthermore, strong negative correlation coefficients were observed between Ca, P, and ΣREE, while a positive correlation was reported between Si and P in apatite and monazite. Chondrite normalized spider diagrams indicate a negative slope (LREE/HREE>1) in all of the samples. Moreover, a strong negative correlation was observed between Sr and Y in the studied apatite and monazites. Fluid inclusions within the apatites were classified into eight groups: a) one-phase gaseous inclusions, b) one-phase liquid inclusions, c) two-phase liquid rich inclusions (L+V), d) two-phase gas-rich inclusions (V+L), e) two-phase liquid- solid inclusions (L+V), f) three-phase inclusions (V-L-S), g) three-phase CO2 bearing inclusions associated with formation of clathrate, and h) melt inclusions. The composition of the fluid inclusions is plotted in magmatic and hydrothermal fields. The salinity of most of the inclusions is low to medium (5-21 wt.% NaCl) and homogenization temperature ranges from 250 to 350˚C. Also, a limited number of fluid inclusions were homogenized in the range of 378-486 ˚C, indicating high salinity (43 to 54 wt.% NaCl). The fluid trapping depths were measured to be in the range 100-1700 m.   Discussion The Esfordi iron-apatite deposit is located NE of Bafq, Yazd province and it hosts three types of apatite mineralization in massive, vein, and disseminated forms, as well as REE-bearing minerals. Periodic variations in mineralizing fluid is evidenced by changes in REE content of the studied minerals. The presence of monazite in dark phases of the host apatite mineral indicates leaching of REE from the host apatite and redeposition during the nucleation of monazite grains (Heidarian et al., 2017). Mineralogical data indicated that the apatites are of the fluorapatite type with minor contents of chloride (Rajabzadeh et al., 2013). The quantities of Sr and Y in the studied minerals indicate a strong negative correlation, consistent with magmatic differentiation. In addition, the concentrations of Mn, Sr, and Y support the granitoid origin of the Esfordi deposit (Belousova et al., 2002). Microthermometric data plotted on magmatic and hydrothermal fields indicated that mixing fluids and boiling are the important factors in mineralization. Upon the obtained data of the present study, main parts of the Esfordi iron phosphate deposit have been formed at temperatures ranging from 146 to 486˚C and depths of 100 to 1700 m.   Acknowledgements The authors appreciate Shiraz University Research Council for their support of this work. The Director General and personnel of the Esfordi Mine Company are acknowledged for their assistance in the field works.   References Belousova, E.A., Griffin, W.L., O’Reilly, S.Y. and Fisher, N.I., 2002. Apatites as indicator mineral for mineral exploration: trace-element compositions and their relationship to host rock type. Journal of Geochemical Exploration, 76(1): 45–69. https://doi.org/10.1016/S0375-6742(02)00204-2 Heidarian, H., Alirezaei, S. and Lentz, D., 2017. Chadormalu Kiruna-type magnetite–apatite deposite, Bafq district, Iran: Insights in to hydrothermal alteration and petrogenesis from geochemical, fluid inclusion and sulfur isotope data. Ore Geology Reviews, 83(7): 43–62. https://doi.org/10.1016/j.oregeorev.2016.11.031 Rajabzadeh, M.A., Hoseini. K. and Moosavinasab. Z., 2013. Mineralogical and geochemical studies on apatites and phosphate host rocks of Esfordi deposit, Yazd province, to determine the origin and geological setting of the apatite. Journal of Economic Geology, 6(2): 331–353. (in Persian with English abstract) https://dx.doi.org/10.22067/ECONG.V6I2.20956 }, keywords = {Mineralogy,Geochemistry,Microthermometry,apatite,Monazite,Rare Earth Element Minerals,Esfordi deposit,Bafq}, title_fa = {کانی‌ شناسی، زمین‌ شیمی و ریزدماسنجی میان‌ بارهای سیال کانی آپاتیت و کانی‌ های عناصر کمیاب خاکی در کانسار اسفوردی، شمال شرق بافق، استان یزد}, abstract_fa = {کانسار آهن-‌آپاتیت اسفوردی در شمال‌شرق شهر بافق قرار دارد. آپاتیت دارای الگوی ناهمگن رنگ با فاز‌های تاریک و روشن است که با غلظت‌های متفاوت REE و عناصر Si، Cl وF  مشخص می‌شود. دو نسل کانی مونازیت به صورت گسترده و زنوتیم به صورت معدود در بلورهای آپاتیت تشکیل شده‌اند. نسل دوم مونازیت دارای نسبت بالاتر La/Ce و غنی‌شدگی عناصر La، Pr و Nd در مقایسه با مونازیت نسل اول است. توزیع عناصر کمیاب خاکی در آپاتیت و مونازیت نشان‌دهنده غنی‌شدگی از LREE بوده که ویژگی کانسار‌های آهن-‌آپاتیت نوع کایروناست. دو محدوده مشخص از چگالی در میان‌بار‌های سیال نشان‌دهنده حضور دو نوع سیال ماگمایی با دما و شوری بالا و گرمابی با دما و شوری کم تا متوسط است. اختلاط سیال و کاهش دما عوامل مهم در ته‌نشست کانسار هستند. بخش عمده و اصلی کانسار اسفوردی در دمایی بین 146 تا 486 درجه سانتی‌گراد تشکیل‌شده است.}, keywords_fa = {کانی‌ شناسی,زمین‌ شیمی,ریزدماسنجی,آپاتیت,مونازیت,کانی‌ های عناصر کمیاب خاکی,کانسار اسفوردی,بافق}, url = {https://econg.um.ac.ir/article_40214.html}, eprint = {https://econg.um.ac.ir/article_40214_57d26f79a1855a1e9e2a28e5083ec880.pdf} } @article { author = {Bigdeli, Roya and Tale Fazel, Ebrahim and Maanijou, Mohammad}, title = {Mineralization, ore mineral chemistry and sulfur stable isotopes at the Chaldaq gold prospect (north Takab): evidence for gold formation mechanism}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {85-111}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.83781}, abstract = {Introduction The Takab-Angouran ore field, one of the Iran’s largest gold districts, is located in northwestern Zagros and belongs to the northwestern part of the Sanandaj-Sirjan Zone. This area has a dominant NW-SE structural trend and is spatially associated with the Sanandaj-Sirjan zone. Its geological and petrological characteristics seem to have closer affinities to the Central Iran zone. There are no chronological data on the ultramafic rocks or associated amphibolites, granulites and calc-silicates of the Takab area and the petrogenesis of the ultramafic rocks and their tectonic relations with other parts of the metamorphic complex are unclear. A Neoproterozoic-Lower Cambrian age for the protoliths of Takab-Angouran ore field seems likely, in view of comparable lithology, stratigraphy and geochronology with the Central Iran zone. The Chaldaq gold prospect is located in the Takab-Angouran ore field, NW Iran, within Iman Khan NW-trending anticline. The rock units at the mining area mainly consist of Precambrian sequence (Iman Khan schist, Chaldaq limestone and Zarshuran black shale) overlain by Cambro-Ordovician limestone and Oligo-Miocene Qom Formations (Mehrabi et al., 1999). The gold mineralization in the Chaldaq prospect is hosted by Chaldaq carbonaceous sedimentary rocks. Two major sets of faults which were recognized by Mehrabi et al., 1999 at the Zarshuran mine are: 1) northwest (310–325) and 2) southwest (255–265). Herein, we report on the textural, paragenetic relationships, mineral chemistry and sulfur isotopes of the Chaldaq prospect. This study is focused on: (1) documenting the chemical composition of different sulfides, (2) determining the chemical state of gold in iron sulfides, (3) determining the sulfur activity, and (4) source of sulfur.   Materials and methods About 70 rock samples were collected from various parts of the deposit for determinations of mineralogy, mineral texture, mineral chemistry and sulfur isotope. The polished thin sections were carbon coated and analyzed on a Camera SX100 electron microprobe at the Iranian Mineral Processing Research Center (IMPRC), Karaj. The detection limits for major and minor elements are approximately 0.05 and 0.01 wt.%, respectively. Sulfur isotope analyses were conducted on 0.05 g of a 200-mesh sized of pyrite and realgar which were handpicked and checked under a binocular microscope to ensure purity of >98%. Each sample was reacted with Cu2O powder to produce SO2. The SO2 gas was collected and purified, and followed by S isotopic analysis using a MAT252 mass spectrometer at stable isotope laboratory of the University of Arizona. The δ34S values were reported relative to Vienna Cañon Diablo Troilite (VCDT), and analytical precision is ±0.2‰.   Results and discussion Based on field and petrographic observations, three mineralization stages including diagenetic, hydrothermal (early-ore, main-ore and late-ore substages), and supergene stages were identified at the Chaldaq deposit. At least six types of pyrite and arsenian pyrite were recognized at the Chaldaq deposit. On the basis of EPMA results, gold with 10 to 80 ppm Au content occurs as solid solution (Au+)in arsenian pyrite [(Fe2+As3+)S2Au2.S0]. Various studies have documented that gold in the primary ores of sediment-hosted gold deposits is largely hosted by arsenian pyrite, and that gold in occurs as a substituting cation in the form of  solid solution (Au+) and/or as nanoparticles of native gold (Au0) (Cook and Chryssoulis, 1990; Fleet and Mumin, 1997; Reich et al., 2005). Au– and Au3+ have also been suggested to occur as solid solution in pyrite (Arehart et al., 1993; Li et al., 2003). The understanding of the chemical state of gold in iron sulfides is important for deep understanding of gold depositional mechanism in sediment-hosted gold deposits. Main-ore substage sulfide minerals has δ34S values ranging from 3.5 to 6.5 ‰ (avg. 5‰, n=6). The Fe content of sphalerites from the main-ore indicates that sphalerite precipitated from relatively low fS2 fluid. Based on all evidence, it can be said that sulfur mineralization of the Chaldaq prospect has been formed by the performance of oxidized hydrothermal fluid on organic-bearing carbonaceous host rocks (at the Chaldaq unit) and the systematic subtraction of H2S reductive species from that environment. Considering the low temperature (fS2 between -14 to -16) and the acidic to neutral pH (presence of kaolinite and illite) for the main-ore stage of hydrothermal mineralization in the Chaldaq prospect, probably the major contribution of sulfur is in the form of H2S. References Arehart, G.B., Chryssoulis S.L. and Kesler, S.E., 1993. Gold and arsenic in iron sulfides from sediment-hosted disseminated gold deposits: implications for depositional processes. Economic Geology, 88(3): 171–185. https://doi.org/10.2113/gsecongeo.88.1.171 Cook, N.J. and Chryssoulis S.L., 1990. Concentrations of invisible gold in the common sulfides. Canadian Mineralogist, 28(3): 1–16. https://doi.org/10.1007/s00126-0140562-z Fleet, M.E. and Mumin, A.H., 1997. Gold-bearing arsenian pyrite and marcasite and arsenopyrite from Carlin trend gold deposits to laboratory synthesis. American Mineralogist, 82(3): 182–193. https://doi.org/10.2138/am-1997-1-220 Li, J.L., Qi, F. and Xu, Q.S., 2003. A negatively charged species of gold in minerals–further study of chemically bound gold in arsenopyrite and arsenian pyrite. Neues Jahrbuch für Mineralogie-Abhandlungen, 5(2): 193–214. https://doi.org/10.1127/0028-3649/2003/2003-0193 Mehrabi, B., Yardley, B.W.D. and Cann, J.R., 1999. Sediment-hosted, disseminated gold mineralisation at Zarshuran, NW Iran. Mineralium Deposita, 34(3): 656–671. https://doi.org/10.1007/s001260050227 Reich, M., Kesler, S.E., Utsunomiya, S., Palenik, C.S., Chryssoulis, S.L. and Ewing, R.C., 2005. Solubility of gold in arsenian pyrite. Geochimica and Cosmochimica Acta, 69(6): 2781–2796. https://doi.org/10.1016/j.gca.2005.01.011}, keywords = {Arsenian pyrite,Ore mineral chemistry,Sulfur isotope,gold,Chaldaq prospect,Zarshuran}, title_fa = {کانه زایی، شیمی کانه ها و ایزوتوپ های پایدار گوگرد در اندیس طلای چالداغ (شمال تکاب): شواهدی برای دستیابی به سازوکار تشکیل طلا}, abstract_fa = {منطقه اکتشافی چالداغ با عیار متوسط 5/4 گرم در تن به‌عنوان یکی از اندیس­ های پرعیار کانسار زرشوران، در شمال تکاب واقع‌شده است. از لحاظ ساختاری این منطقه در غرب گسل رانده قینرجه و طاقدیس ایمان­خان (راستای NW) قرار دارد و واحد کربنات آهن­دار چالداغ به سن نئوپروتروزوئیک-کامبرین بالایی، سنگ میزبان اصلی کانه ­زایی است. طبق شواهد ریزکاوالکترونی، طلا به‌صورت محلول جامد با کاتیون Au+ و محتوای 10 تا 80 گرم در تن (ppm) در ترکیب کانه آرسنین­پیریت با فرمول (Fe2+As3+)S2Au2.S0 تمرکز دارد. شواهد ایزوتوپ پایدار گوگرد بر روی کانه ­های سولفیدی رالگار و پیریت گویای مقادیر δ34SCDT بین 5/3 تا ‰ 5/6 (متوسط ‰ 5 در تعداد 6 نمونه)، است. با توجه به مقادیر FeS mol% اسفالریت­، تغییرات LogfS2 در اندیس چالداغ بین 14- تا 16- به‌دست آمد که منطبق با شرایط سولفیداسیون متوسط است. طبق شواهد به‌نظر می­ رسد در اندیس طلای چالداغ، سیال گرمابی غنی از H2S هم‌ زمان با فرایند کربنات­ زدایی و آزاد‌شدن مقادیر بالای Fe2+ و As3+ در محیط، با این کاتیون­ ها واکنش داده و آرسنین­پیریت تشکیل‌ شده است. در پی این فرایند، ضمن کاهش محتوای H2S محیط، کمپلکس­ های بی­سولفیدی Au(HS)2– تحت شرایط خنثی تا اسیدی و ماهیت اکسیدی محیط ناپایدار شده و به دنبال آن ته‌نشینی طلا رخ‌داده است.}, keywords_fa = {آرسنین پیریت,شیمی کانه,ایزوتوپ گوگرد,طلا,اندیس چالداغ,زرشوران}, url = {https://econg.um.ac.ir/article_40215.html}, eprint = {https://econg.um.ac.ir/article_40215_0e2f4ff6a3cca5abe2cca0a3b0a756e9.pdf} } @article { author = {Sayari, Mohammad and Sharifi, Mortaza}, title = {Evolution of the volcanic mechanism in the central part of the Urumieh-Dokhtar magmatic arc}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {113-144}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.85642}, abstract = {Introduction Cenozoic volcanic activities in the Urumieh-Dokhtar Magmatic Arc (UDMA) have occurred in three main pulses of Eocene, upper Oligocene-Pliocene, and Pio-Quaternary (Dilek et al., 2010, Sayari, 2015). Magmatic activities in the UDMA until a few years ago were marked with calc-alkaline and occasionally shoshonitic signatures. Recent studies have reported post-collisional adakites in some parts of the UDMA (e.g., Ghadami et al., 2008; Omrani et al., 2008; Sayari, 2015; Sayari and Sharifi, 2018). Since magmatic genesis of calc-alkaline, shoshoitic, and especially adakites are absolutely different, variation in the volcanism nature of Iran is a key to recognition of geodynamic evolution of Iran. This study tries to analyze the volcanic evolution in the central part of the UDMA by systematically processing of geochemical database for three main Cenozoic volcanic pulses.       Materials and methods Whole rock reliable ICP-MS analysis data from scientific texts having exact location coordinates were gathered to form a geochemical geodatabase which includes 99 samples. This database spatially covers around 200 km in the central part of the UDMA from 51°15´E and 33°47´N (north of Isfahan) to 52°57´E and 32°35´N (east of Isfahan).     Results Analysis of the geochemical geodatabase indicates that none of the samples belong to alkaline and tholeiitic magmatic series. About 71 percent of group 1 (volcanic pulse of Eocene) are calc-alkaline, and the remaining 29 percent are shoshonitic. About 67 percent of group 2 (volcanic pulse of Oligocene-Miocene) are shoshonitic, and the remaining 33 percent are calc-alkaline. About 88 percent of group 3 (volcanic pulse of Plio-Quaternary) are adakite, and the remaining nearly 12 percent are both calc-alkaline/shoshonitic (samples CN4, JS13, OG4 and SK1 of Khodami, 2009). Adakitic samples are situated in two areas in Joshaghan-Ghohrud and Kajan-Kahang. Sayari and Sharifi (2018) showed that there is a correlation between UDMA adakites and positive lithospheric thickness anomalies. They showed that adakites in the central part of UDMA are restricted to 4 regions exactly where lithosphere and crust are anomalously thicker than the surrounding. In the areas where adakites lie, lithosphere-asthenosphere boundary (LAB) is situated deeper than 212 km (Sayari and Sharifi, 2018). The geochemical aspect of the studied adakites which are all related to the third volcanic pulse of UDMA shows that they have been derived from the subducted slab. They do not have adakite-like or crust-derived adakites characteristics.   Discussion The results indicate that volcanic activities from Eocene to Quaternary have evolved from calc-alkaline to shoshonitic signatures and then turned into adakitic nature. Calc-alkaline and shoshonitic magmatism resulted from partial melting of the mantle wedge, while adakitic magmatism resulted from partial melting of the subducted slab. This means that the origin of the third volcanic pulse has shifted from mantle wedge to slab. According to the La/Sm versus La diagram (Aldanmaz, 2000) calc-alkaline samples have been derived from about 15% partial melting of the spinel-garnet lherzolite, and the shoshonitic samples have resulted from about 3% partial melting of the spinel-garnet lherzolite. Based on La/Yb versus Yb diagram (Bourdon et al., 2002), adakites from Kajan-Kahang have been derived from about 10% partial melting of the garnet amphibolite. Moreover, the Adakites from Joshaghan-Ghohrud have resulted from about 6% partial melting of the hornblende eclogite.   Acknowledgment The authors would like to thank the management of the Regional Water Company of Isfahan, Graduate School of the University of Isfahan, and Ms. Fatemeh Darvishzadeh.T   References Aldanmaz, E., Pearce, J.A., Thirlwall, M.F. and Mitchell, J.G., 2000. Petrogenetic evolution of late Cenozoic, post-collision volcanism in western Anatolia, Turkey. Journal of Volcanology and Geothermal Research, 102(1–2): 67–95. https://doi.org/10.1016/s0377-0273(00)00182-7 Bourdon, E., Eissen, J.P., Gutscher, M.A., Monzier, M., Samaniego, P., Robin, C., Bollinger, C. and Cotton, J., 2002. Slab melting and slab melt metasomatism in the Northern Andean Volcanic Zone: adakites and high-Mg andesites from Pichincha volcano (Ecuador). Bulletin de la Société Géologique de France, 173(2): 195–206. https://doi.org/10.2113/173.3.195 Dilek, Y., Imamverdiyev, N. and Altunkaynak, S., 2010. Geochemistry and tectonics of Cenozoic volcanism in the Lesser Caucasus (Azerbaijan) and the peri-Arabian region: collision-induced mantle dynamics and its magmatic fingerprint. International Geology Review, 52(4–6): 536–578. Ghadami, G., Moradian, A. and Mortazavi, M., 2008. Post-collisional Plio–Pleistocene adakitic volcanism in Central Iranian volcanic belt: geochemical and geodynamicimplications. Journal of Sciences, Islamic Republic of Iran, 19(3): 223–235. Retrieved June 11, 2021 from https://journals.ut.ac.ir/pdf_31896_3d5550b30b2590c75543469f305410a2.html Khodami, M., 2009. Petrology of Plio-Quaternary volcanic rocks in south-east and north-west of Isfahan. Ph.D. Thesis, University of Isfahan, Isfahan, Iran, 174 pp. (in Persian with English abstract) Retrieved June 11, 2021 from https://lib.ui.ac.ir/dL/search/default.aspx?Term=6027&Field=0&DTC=3 Omrani, J., Agard, P., Witechurch, H., Benoit, M., Prouteau, G. and Jolivet, L., 2008. Arc magmatism and subduction history beneath the Zagros Mountains, Iran: a new report of adakites and geodynamic consequences. Lithos, 106(3–4): 380–398. https://doi.org/10.1016/j.lithos.2008.09.008 Sayari, M., 2015. Petrogenesis and evolution of Oligocene-Pliocene volcanism in the central part of Urumieh-Dokhtar Magmatic Arc (NE of Isfahan). Ph.D. Thesis, University of Isfahan, Isfahan, Iran, 195 pp. (in Persian with English abstract) Retrieved June 11, 2021 from https://lib.ui.ac.ir/dl/search/default.aspx?Term=12518&Field=0&dtc=3 Sayari, M., Sharifi, M., 2018. Anomalies in the depth of the asthenospheric mantle: key to the enigma of adakites in the Urumieh-Dokhtar magmatic arc. Neues Jahrbuch für Mineralogie-Abhandlungen: Journal of Mineralogy and Geochemistry, 195(3): 227–245. https://doi.org/10.1127/njma/2018/0093}, keywords = {Volcanism,Cenozoic,partial melting,Adakite,Urumieh-Dokhtar}, title_fa = {تحول سازوکار آتشفشانی در بخش میانی کمان ماگمایی ارومیه-دختر}, abstract_fa = {در این پژوهش پایگاه ژئوشیمی زمین‌مرجع متشکل از 99 آنالیز شیمیایی در طول حدود 200 کیلومتر از بخش میانی کمان ماگمایی ارومیه-‌دختر (از شمال تا شرق اصفهان) مورد کنکاش قرار‌گرفت. این محدوده بین طول­ های جغرافیایی ´15°51 و ´57°52 شرقی و عرض­ های جغرافیایی ´35°32 و ´47°33 شمالی واقع‌شده ­است. این پایگاه داده از بین داده‌های ژئوشیمیایی سنگ کل منتشر‌شده در پهنه مورد بررسی که دو شرط مهم را داشته­ اند، انتخاب شدند. اول اینکه داده ­ها دارای مختصات جغرافیایی صحیح و یا نقشه مختصات­ دار باشند، دوم اینکه آنالیزها توانایی تفکیک سری­ های ماگمایی و تشخیص آداکیت ­ها را داشته­ باشند (عناصر کمیاب Y، Yb، Lu، Sr با دقت مناسب گزارش شده­ اند). این آنالیزها در سه دسته سنی ائوسن، الیگوسن- پلیوسن و پلیو-کواترنر قرار می­ گیرند. یک نمودار جریانی برای شناسایی سری ماگمایی نمونه ­ها طراحی‌شد و کلیه داده­ ها به‌صورت نظام­ مند بر مبنای آن مورد تحلیل قرار گرفتند. نتایج نشان می­ دهد که ماهیت ماگماتیسم فاز اول اغلب کالک‌آلکالن، فاز دوم معمولاً شوشونیتی و فاز سوم اغلب آداکیتی بوده­ است. با استفاده از نمودارهای تعیین درصد ذوب‌بخشی سنگ­های ماگمایی مشخص­شد که نمونه ­های کالک‌آلکالن از ذوب‌بخشی حدود 15 درصد گوه گوشته­ ای اسپینل-گارنت لرزولیت به‌دست آمده‌اند. برآورد می ­شود که نمونه­ های شوشونیتی از ذوب‌بخشی حدود 3 درصد گوه گوشته ­ای با ترکیب اسپینل-‌گارنت لرزولیت حاصل شده­ اند. آداکیت­ ها حاصل ذوب پوسته اقیانوسی فرورانده‌شده هستند و بر اساس درصد ذوب‌بخشی منشأ به دو دسته قابل تفکیک ­اند. دسته اول، نمونه ­های منطقه کجان و کهنگ که از ذوب‌بخشی حدود 10 درصد گارنت آمفیبولیت حاصل شده ­اند و دسته دوم، نمونه­ های منطقه جوشقان- قهرود که نزدیکی بیشتری با سنگ منشأ هورنبلند اکلوژیت دارند، ذوب‌بخشی حدود 6 درصد نشان می ­دهند. البته باید توجه داشت این تفاسیر برمبنای داده‌های موجود است و در آینده با در دست‌ داشتن داده‌های صحیح مختصات‌دار بیشتر، این پایگاه داده می‌تواند کامل ­تر شده و ارزیابی دقیق­ تری از تحولات ژئوشیمی سنگ ­های آتشفشانی منطقه ارائه نماید.}, keywords_fa = {آتشفشانی,سنوزوئیک,ذوب‌ بخشی,آداکیت,ارومیه-‌دختر}, url = {https://econg.um.ac.ir/article_40218.html}, eprint = {https://econg.um.ac.ir/article_40218_f821106fe1fdde92c1dad5a74d5bdea0.pdf} } @article { author = {Samadi, Ramin and Torabi, Ghodrat and Mirnejad, Hassan}, title = {Geochemistry, origin and anatexis temperature of monzogranite formation in Mount Khalaj (Mashhad, Iran)}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {145-164}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.84933}, abstract = {Introduction Granitoids are the main rock units in the continental crust. Study of granitoids reveals significant information on tectonic mantle and upper crust. Many researchers have investigated petrogenesis and origin of granitoids (e.g., Chappell and White, 2001; Barbarin, 1999; Frost et al., 2001). For example, Chappell and White (1992), Pitcher (1993) and Chappell et al., (1998) have divided granites into two major groups of: (1) I-type granites (high-temperature or Cordellerian granitoids, including low-K granitoid to high-Ca tonalite, without inherited zircons) formed by partial melting of mafic rocks at >1000 ℃ in mantle or subduction zones of continental margins, and (2) S-type (low-temperature or Caledonian granitoids with inherited zircons) granites formed by partial melting of felsic crust at ~700-800 ℃. Northeast of Iran is a key location for studying the Cimmerian Orogeny, which is related to the Late Triassic collision between it and Eurasia, and the closure of the Paleo-Tethys (Samadi et al., 2014). Mesozoic Mashhad granitoids have cropped out along with the Paleo-Tethys suture zone. Distinct granitoid suites, i.e., monzogranite, granodiorite, tonalite, and diorite occur in Mount Khalaj located in the south of Mashhad. It comprises of monzogranite and granodiorite. However, monzogranite is the most abundant. To study the plutonic events during the Turan and Central Iran collision, the origin and tectonic setting of monzogranite of Mount Khalaj are investigated in this study based on whole rock geochemical data.   Materials and methods This research study is based on field studies and petrography. Fresh thin sections samples were selected for geochemical analysis. Whole rock composition was measured on pressed powder tablets by X-ray fluorescence (XRF) using a Philips PW 1480 wavelength dispersive spectrometer with a Rh-anode X-ray tube and a 3 MeV electron beam Van de Graaff Accelerator, at the center for Geological Survey of Iran. The trace element data of a sample was measured at the Activation Laboratories, Ontario, Canada (ActLabs). Samples were digested by lithium metaborate/tetraborate fusion and analyzed with a Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP/MS. GCDkit 4.1 and CorelDraw software packages were used for plotting diagrams and calculation of saturation temperatures.   Results The Khalaj granitoid is mineralogically composed of quartz, potassic feldspar, plagioclase, mica, and accessory minerals of zircon and apatite. Geochemically, it is an unaltered acidic intrusion with ~72-73 wt.% SiO2. It is a granitoid (monzogranite) based on various classification diagrams (e.g., Cox et al., 1979; etc.). It shows the peraluminous nature (A/CNK~ 1.08-1.24) with negative Eu anomaly of ~0.62-0.73 (Eu/Eu*<1), low HREE and high LREE and LILE contents.   Discussion Geochemically, the low HREE and high LREE and LILE content in the Mount Khalaj monzogranite indicate a more differentiated melt for it. Monzogranite samples from the Khalaj-Khajeh Morad regions are similar to ferroan alkali-calcic, felsic peraluminous S-type granitoids based on discrimination diagrams by various researchers (e.g., Chappell and White, 2001; Villaseca et al., 1998). In fact, the Mount Khalaj monzogranite is a collisional granite (based on diagrams by: Batchelor and Bowden, 1985; Sahin et al., 2004), produced by anatexis and partial melting of felsic upper crust pelitic sediments (based on diagrams by: Almeida et al., 2007; Patiño Douce, 1999). It is classified as a low-temperature S-type granite formed at 730-800 ℃ (based on the diagram of Rapp and Watson, 1995), with TZr of ~732-745 ℃ (by using GCDKit software). Therefore, S-type syn- to post-collisional Mount Khalaj monzogranite is a consequence of partial melting (anatexis) of hydrous sedimentary rocks of upper crust after Paleo-Tethys subduction under Turan plate and continental collision and compressional tectonism.   References Almeida, M.E., Macambira, M.J.B. and Oliveira, E.C., 2007. Geochemistry and zircon geochronology of the I-type high-K calc-alkaline and S-type granitoid rocks from southeastern Roraima, Brazil: Orosirian collisional magmatism evidence (1.97-1.96 Ga) in central portion of Guyana Shield. Precambrian Research, 155(1–2): 69–97. https://doi.org/10.1016/j.precamres.2007.01.004 Barbarin, B., 1999. A review of the relationships between granitoid types, their origin and their geodynamic environments. Lithos, 46(3): 605–626. https://doi.org/10.1016/S0024-4937(98)00085-1 Batchelor, R.A. and Bowden, P., 1985. Petrogenetic interpretation of granitoid rocks series using multicationic parameters. Chemical Geology, 48(1–4): 43–55. https://doi.org/10.1016/0009-2541(85)90034-8 Chappell, B.W. and White, A.J.R. 2001. Two contrasting granite types: 25 years later. Australian Journal of Earth Sciences, 48: 489–499. https://doi.org/10.1046/j.1440-0952.2001.00882.x Chappell, B.W. and White, A.J.R., 1992. I- and S-type granites in the Lachlan fold belt. Earth and Envioronmental Sciennce Transactions of The Royal Society Edinburgh, 83(1–2): 1–26. https://doi.org/10.1017/S0263593300007720 Chappell, B.W., Bryant, C.J., Wyborn, D., White, A.J.R. and Williams, I.S., 1998. High- and low-temperature I-type granites. Resource Geology, 48(4): 225–236. https://doi.org/10.1111/j.1751-3928.1998.tb00020.x Cox, K.G., Bell, J.S. and Pankhurst, R.J., 1979. The interpretation of igneous rocks. Allen and Unwin, London, 450 pp. https://doi.org/10.1007/978-94-017-3373-1 Frost, B.R., Barnes, C.G., Collins, W.J., Arculus, S.R.J., Ellis, D.J. and Frost, C.D., 2001. A geochemical classification for granitic rocks. Journal of Petrology, 42(11): 2033–2048. https://doi.org/10.1093/petrology/42.11.2033 Patiño Douce, A.E., 1999. What do experiments tell us about the relative contributions of crust and mantle to the origins of granitic magmas? Geological Society, London, Special Publication, 168: 55–75. https://doi.org/10.1144/GSL.SP.1999.168.01.05 Pitcher, W.A.S., 1993. The nature and origin of granite. Chapman and Hall, London, 321 pp. https://doi.org/10.1007/978-94-011-5832-9 Rapp, R.P. and Watson, E.B., 1995. Dehydration melting of metabasalt at 8–32 kbar: Implications for continental growth and crust-mantle recycling. Journal of Petrology, 36(4): 891–931. https://doi.org/10.1093/petrology/36.4.891 Sahin, S.Y., Güngör, Y. and Boztuğ, D., 2004. Comparative petrogenetic investigation of Composite Kaçkar Batholith granitoids in Eastern Pontide magmatic arc-Northern Turkey. Earth, Planet and Space, 56(4): 429–446. https://doi.org/10.1186/BF03352496 Samadi, R., Mirnejad, H., Kawabata, H., Valizadeh, M.V., Harris, C. and Gazel, E., 2014. Magmatic garnet in the Triassic (215 Ma) Dehnow pluton of NE Iran and its petrogenetic significance. International Geology Review, 56(5): 596–621. https://doi.org/10.1080/00206814.2014.880659 Villaseca, C., Barbero, L. and Herreros, V., 1998. A re-examination of the typology of peraluminous granite types in intracontinental orogenic belts. Earth and Envioronmental Sciennce Transactions of The Royal Society Edinburgh, 89(2): 113–119. https://doi.org/10.1017/S0263593300007045}, keywords = {Petrography,Geochemistry,monzogranite,Mesozoic,Khalaj,Mashhad}, title_fa = {ژئوشیمی، خاستگاه و دمایی آناتکسی تشکیل مونزوگرانیت‌ خلج (مشهد، ایران)}, abstract_fa = {سنگ‌های مونزوگرانیتی گروهی از گرانیتوئیدهای مشهد با سن مزوزوئیک هستند که در منطقه خلج (واقع در جنوب‌ شهر مشهد) رخنمون دارند. این سنگ‌ها دارای کانی‌های کوارتز، پتاسیم فلدسپار، پلاژیوکلاز، میکا و کانی های فرعی زیرکن و آپاتیت هستند. از دیدگاه ژئوشیمیایی، در مونزوگرانیت خلج میزان کم‌ HREE و میزان بالای LREE و LILE نشان‌دهنده درجات بالای تفریق مذاب مولد آن است. بنابراین، مونزوگرانیت خلج از گروه گرانیتوئیدهای فروئن، آلکالی کلسیک، پرآلومین، فلسیک نوع S و محصول ذوب‌بخشی رسوبات پوسته بالایی در دمای نزدیک به 730 تا 800 درجه سانتی‌گراد است. دماهای اشباع‌شدگی ماگما از زیرکنیم هنگام تشکیل زیرکن کمتر از 800 (تقریباً 732 تا 745) درجه سانتی‌گراد محاسبه‌شد. با فرورانش پالئوتتیس زیر ورقه توران و برخورد قاره‌ای، پوسته‌ بالایی در اثر فرایندهای زمین‌ساختی فشاری دچار ذوب‌بخشی شده‌ و توده‌های نفوذی مونزوگرانیتی هم‌زمان ‌با برخورد تا پسابرخوردی نوع S خلج تشکیل شده‌اند.}, keywords_fa = {سنگ‌ نگاری,ژئوشیمی,مونزوگرانیت,مزوزوئیک,خلج,مشهد}, url = {https://econg.um.ac.ir/article_40219.html}, eprint = {https://econg.um.ac.ir/article_40219_27c539caf8c70f8752ac1a166261c85a.pdf} } @article { author = {Karami, Fatemeh and Kouhestani, Hossein and Mokhtari, Mir Ali Asghar and Azimzadeh, Amir Morteza}, title = {The Halab deposit, SW Zanjan: Volcanogenic massive sulfide Zn–Pb (Ag) mineralization, Takab–Takht-e-Soleyman–Angouran metallogenic district}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {165-192}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.76448}, abstract = {Introduction The Halab Zn–Pb (Ag) deposit, 125-km southwest of Zanjan, is located in the Takab–Takht-e-Soleyman–Angouran metallogenic district (TTAMD), Sanandaj-Sirjan zone. Several types of deposits are present in the TTAMD, including nonsulfide Zn–Pb deposits, sediment-hosted epithermal gold deposits, epithermal precious and base metal deposits, skarn and volcano-sedimentary iron deposits, and massive sulfide Pb-Zn (Ag) deposits. The most important deposits discovered to date within the TTAMD are the Angouran nonsulfide Zn–Pb deposit (Gilg et al., 2006; Boni et al., 2007; Daliran et al., 2013), Zarshuran sediment-hosted epithermal gold deposit (Mehrabi et al., 1999; Asadi et al., 2000; Daliran et al., 2002), and Agdar’reh epithermal gold deposit (Daliran, 2008). Other important deposits or occurrences include Touzlar, Ay Qalasi, Arabshah, Qozlou, Shahrak, Goorgoor, Mianaj, and Halab (Heidari et al., 2015; Mohammadi Niaei et al., 2015; Najafzadeh et al., 2017; Nafisi et al., 2019). To date, no detailed study has been reported to understand the characteristics of Zn–Pb (Ag) mineralization at the Halab deposit. This paper presents the geologic framework, mineralization characteristics, and lithogeochemical signatures of the Halab deposit with emphasis on ore genesis. Identification of these characteristics can serve as a model for exploration of Zn–Pb (Ag) mineralization in the Halab area and other parts of the TTAMD.   Materials and methods Detailed field work was carried out in the Halab deposit. Sixteen polished-thin and thin sections from host rocks and ore horizon were studied by conventional petrographic and mineralogic methods at the University of Zanjan. In addition, a total of 10 samples from barren host rocks and ore horizon at the Halab deposit were analyzed by ICP–MS for trace elements and REE compositions at Zarazma Co., Tehran, Iran.   Results and Discussion The host rocks in the Halab area consist of Precambrian deformed metamorphic rocks (equal to the Kahar Formation) that are unconformably overlain by dolomitic marble of the Jangoutaran unit. The metamorphic sequence is composed of pelitic (garnet mica schist, biotite muscovite schist, calcite biotite schist), mafic (biotite amphibole schist and actinolite schist), and felsic (quartz schist) schists intercalated with marble, and quartzite. These rocks are metamorphosed in green schist to amphibolite facies. Mineralization in the Halab deposit occurs as NE-trending foliation-parallel Zn‒Pb (Ag) stratiform horizon hosted by quartz schist units. The ore horizon reaches up to 300 m in length and 3 to 5 m in width, and it is generally 75° SE dipping. Chloritization and silicification of the host rocks are close to the ore horizon, while the sericitic alteration is envelope of the chloritization and silicification. Sphalerite, galena, pyrite and chalcopyrite are the main sulfide minerals in the Halab deposit based on mineralography. Smithsonite, cerussite, chalcocite, covellite and goethite have formed as supergene minerals. Quartz, calcite, chlorite and epidote also present as gangue minerals. The ore minerals show laminated, disseminated, massive, brecciated, replacement and vein-veinlet textures. Chondrite-nonmineralized REE pattern of barren quartz schist host rocks and mineralized samples indicate that mineralized samples are enriched in REE. The main characteristics of the Halab deposit reveal that Zn‒Pb (Ag) mineralization at Halab is comparable with laminated and disseminated parts of Bathurst types of massive sulfide deposits.   Acknowledgements The authors are grateful to the University of Zanjan Grant Commission for research funding. Journal of Economic Geology reviewers and editor are also thanked for their constructive suggestions and improved the early version of manuscript.   References Asadi, H.H., Voncken, J.H.L., Kühnel, R.A. and Hale, M., 2000. Petrography, mineralogy and geochemistry of the Zarshuran Carlin-like gold deposit, northwest Iran. Mineralium Deposita, 5(7): 656–671.  https://doi.org/10.1007/s001260050269 Boni, M., Gilg, H.A., Balassone, G., Schneider, J., Allen, C.R. and Moore, F., 2007. Hypogene Zn carbonate ores in the Angouran deposit, NW Iran. Mineralium Deposita, 42(8): 799–820. https://doi.org/10.1007/s00126-007-0144-4 Daliran, F., 2008. The carbonate rock-hosted epithermal gold deposit of Agdarreh, Takab geothermal field, NW Iran, hydrothermal alteration and mineralization. Mineralium Deposita, 43(4): 383–404. https://doi.org/10.1007/s00126-007-0167-x Daliran, F., Hofstra, A.H., Walther, J. and Stüben, D., 2002. Aghdarreh and Zarshuran SRHDG deposits, Takab region, NW Iran. Annual Meeting, Geological Society of America (GSA), Denver, USA. Daliran, F., Pride, K., Walther, W., Berner, Z.A. and Bakker, R.J., 2013. The Angouran Zn (Pb) deposit, NW Iran: Evidence for a two stage, hypogene zinc sulfide-zinc carbonate mineralization. Ore Geology Reviews, 53: 373–402. https://doi.org/10.1016/j.oregeorev.2013.02.002 Gilg, H.A., Boni, M., Balassone, G., Allen, C.R., Banks, D. and Moore, F., 2006. Marble-hosted sulphide ores in the Angouran Zn-(Pb-Ag) deposit, NW Iran: interaction of sedimentary brines with a metamorphic core complex. Mineralium Deposita, 41(1): 1–16. https://doi.org/10.1007/s00126-005-0035-5 Heidari, S.M., Daliran, F., Paquette, J.L. and Gasquet, D., 2015. Geology, timing, and genesis of the high sulfidation Au (-Cu) deposit of Touzlar, NW Iran. Ore Geology Reviews, 65: 460–486. https://doi.org/10.1016/j.oregeorev.2014.05.013 Mehrabi, B., Yardley, B.W.D. and Cam, J.R., 1999. Sediment-hosted disseminated gold mineralization at Zarshuran, NW Iran. Mineralium Deposita, 34(7): 673–696. https://doi.org/10.1007/s001260050227 Mohammadi Niaei, R., Daliran, F., Nezafati, N., Ghorbani, M., Sheikh Zakariaei, J. and Kouhestani, H., 2015. The Ay Qalasi deposit: An epithermal Pb‒Zn (Ag) mineralization in the Urumieh‒Dokhtar Volcanic Belt of northwestern Iran. Neues Jahrbuch für Mineralogie Abhandlungen (Journal of Mineralogy and Geochemistry), 192(3): 263–274. https://doi.org/10.1127/njma/2015/0284 Nafisi, R., Kouhestani, H., Mokhtari, M.A.A., Sadeghi, M., 2019. Geochemistry and tectonomagmatic setting of protolite rocks of meta-volcanics in the Halab metamorphic complex (SW Dandy, Zanjan Province). Journal of Economic Geology, 11(2): 211–235. (in Persian with extended English abstract) https://doi.org/10.22067/ECONG.V11I2.68167 Najafzadeh, M., Ebrahimi, M., Mokhtari, M.A.A. and Kouhestani, H., 2017. The Arabshah occurrence: An epithermal Au–As–Sb Carlin type mineralization in the Takab–Angouran–Takht-e-Soleyman metallogenic zone, western Azerbaijan. Advanced Applied Geological Journal, 6(22): 61–76. (in Persian with English abstract) https://doi.org/10.22055/AAG.2016.12709}, keywords = {Zn–Pb (Ag) mineralization,Volcanogenic massive sulfide,Bathurst type,Halab,Zanjan}, title_fa = {کانسار حلب، جنوب باختر زنجان: کانه زایی روی-سرب (نقره) سولفید توده ای آتشفشان زاد در ناحیه فلززایی تکاب-تخت‌سلیمان- انگوران}, abstract_fa = {کانسار روی- سرب (نقره) حلب در فاصله 125 کیلومتری جنوب­ باختر زنجان قرار‌گرفته و بخشی از ناحیه کانه ­دار تکاب- تخت­ سلیمان- انگوران است. توالی سنگی در محدوده این کانسار متشکل از تناوب شیست­ های پلیتی، مافیک و فلسیک ­همراه با میان‌لایه‌هایی از مرمر و کوارتزیت مربوط به پرکامبرین (معادل سازند کهر) است که در حد رخساره شیست سبز تا آمفیبولیت دگرگون شده ­اند. کانه ­زایی در کانسار حلب با درازای 300 متر و پهنای 3 تا 5 متر به­ صورت چینه­سان و هم ­روند با برگ‌ وارگی درون واحدهای شیست فلسیک (کوارتز شیست) رخ‌داده است. بر اساس بررسی‌های میکروسکوپی، کانه‌های فلزی در کانسار حلب شامل کانی­ های درون­ زاد اسفالریت، گالن، پیریت و کالکوپیریت، کانی­ های مرحله برون­ زاد (اسمیت­زونیت، سروزیت، کالکوسیت، کوولیت و گوتیت) و کانی­ های باطله شامل کوارتز، کلسیت، کلریت و اپیدوت هستند. مهم ­ترین بافت ­های کانسنگ شامل لامینه­ ای، دانه ­پراکنده، توده ­ای، بِرشی، جانشینی و رگه-رگچه ­ای است. دگرسانی ­ها شامل کلریتی‌شدن و سیلیسی‌شدن است. دگرسانی سریسیتی در خارج از افق کانه ­دار توسعه‌یافته و دگرسانی ­های کلریتی و سیلیسی را در‌بر‌گرفته است. مقایسه الگوی عناصر نادر خاکی در کوارتز شیست­ میزبان و نمونه ­های کانه ­دار بیانگر غنی­ شدگی این عناصر (REE = 1046.8∑) در نمونه ­های کانه ­دار است. این امر را می ­توان به شرایط احیایی محیط تشکیل کانه ­زایی مرتبط دانست. با توجه به ویژگی­ های زمین­ شناسی و کانه ­زایی، کانسار حلب را می ­توان معادل­ دگرگون و دگرشکل ­شده بخش‌های لایه ­ای و افشان کانسارهای سولفید توده ای آتشفشان ­زاد نوع بتورست در‌نظر‌گرفت.}, keywords_fa = {کانه‌زایی روی-‌سرب (نقره),سولفید توده‌ای آتشفشان‌زاد,نوع بتورست,حلب,زنجان}, url = {https://econg.um.ac.ir/article_40222.html}, eprint = {https://econg.um.ac.ir/article_40222_2b6bef0b7794d5c2c829aa508f7e3ea9.pdf} } @article { author = {Keykhay-Hosseinpoor, Majid and Kouhsari, Amir Hossein and Hossein Morshedy, Amin and Porwal, Alok}, title = {Porphyry Cu-Au prospectivity modelling using semi-supervised learning algorithm in Dehsalm district, eastern Iran}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {193-213}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.81382}, abstract = {Introduction The identification of potentially mineralized areas has progressed with the use and interpretation of all available exploratory data in the form of mineral potential modeling (MPM) (Yousefi and Nykänen, 2017). Recently, machine learning methods have been a popular research topic in the field of MPM ((Chen and Wu, 2016). Machine learning algorithms that have been used in MPM generally fall into the categories of being supervised or unsupervised. Supervised models, use the location of the known mineral occurrences as training sites (or labeled data). Therefore, these models suffer stochastic bias and error (Zuo and Carranza, 2011). Unsupervised models classify mineral prospectivity of every location based solely on feature statistics of individual evidential data layers ((Abedi et al., 2012). The semi-supervised learning models are a hybrid of supervised and unsupervised learning models that use both labeled and unlabeled data to extract the hidden structure of the data, as well as the relation between the input exploration layers and the output labeled data (Fatehi and Asadi, 2017). The Dehsalm study area forms a part of the Lut metallogenic block of eastern Iran, which is characterized by the subduction zone setting and extensive magmatism (Beydokhti et al., 2015). The objective of this research is to present a prospectivity model to delineate exploration target areas for porphyry Cu-Au mineralization in the study area. For generating a prospectivity model, we used TSVM algorithm, a semi-supervised learning integration technique, to identify the anomalous areas related to the porphyry Cu-Au mineralization. The input layers are selected based on a conceptual model for porphyry Cu-Au mineral system. The performance of the mineral prospectivity maps (MPMs) is evaluated using the various techniques, including the receiver operating characteristic (ROC) curve, an area under curve (AUC) metric.   Materials and methods To apply a process-based understanding of porphyry copper-gold deposit system on the mapping of prospectivity, a conceptual model must be first developed (Fatehi and Asadi, 2017). Such a model should depict critical scale-dependent processes involved in the mineral deposit formation, and a mineral system approach can be followed to aid understanding where, when and why mineral deposits form (Parsa et al., 2016). The spatial data sets used to model porphyry Cu-Au prospectivity of the study area include geological, remote sensing, geophysical, and geochemical data. In this study, semi-supervised support vector machine (TSVM) prospectivity technique is utilized to model porphyry Cu-Au target areas. The TSVM is an extension of SVM that uses the unlabeled data to improve the performances of the classifier. The aim of TSVM algorithm is to find the decision hyper-plane subject to maximize the margin distance in labeled and unlabeled data.   Result In the present study, TSVM and SVM models were applied to Cu-Au prospectivity modeling in the study area. The models were trained based on the location of known Cu-Au mineralization occurrences and non-deposit location using e1071 package in R open-source statistical software (70% of the labeled data were used in training and 30% in the testing phase of learning in both algorithms). The RBF kernel function were used and the optimal values of the kernel parameters were assessed using a 10-fold cross-validation procedure and the best learning performance was selected by correct classification rate. The output of the models highlighted the target areas for porphyry Cu-Au mineralization in the study area. The receiver operating characteristics (ROC) analysis shows that both models perform well, however, the TSVM model yields the best performance.   Discussion To identify exploratory target areas on a regional scale, various supervised and unsupervised approaches have been developed in mineral potential modeling. Supervised methods such as SVM use labeled data to classify exploratory datasets. In this research, a new semi- supervised learning method, TSVM, was applied to model the mineral potential for porphyry Cu-Au mineralization in the Dehsalm exploration zone. The introduced target areas by TSVM method, within the known mineral indices, covered smaller areas than targets identified by SVM model, so planning the detailed exploration phase will be optimal. The result of this research demonstrates the superiority of the semi-supervised learning method in identifying the target areas for planning the exploratory operations.   Acknowledgements We would like to thank the Geological Survey of Iran for providing the exploration data used in this research. The financial support of the South Khorasan Industry, Mine & Trade Organization is gratefully thanked.   References Abedi, M., Norouzi, G.H. and Bahroudi, A., 2012. Support vector machine for multi-classification of mineral prospectivity areas. Computers & Geosciences, 46: 272–283.  https://doi.org/10.1016/j.cageo.2011.12.014 Beydokhti, R.M., Karimpour, M.H., Mazaheri, S.A., Santos, J.F. and Klötzli, U., 2015. U-Pb zircon geochronology, Sr-Nd geochemistry, petrogenesis and tectonic setting of Mahoor granitoid rocks (Lut Block, Eastern Iran). Journal of Asian Earth Sciences, 111: 192–205. https://doi.org/10.1016/j.jseaes.2015.07.028 Chen, Y. and Wu, W., 2016. A prospecting cost-benefit strategy for mineral potential mapping based on ROC curve analysis. Ore Geology Reviews, 74: 26–38. https://doi.org/10.1016/j.oregeorev.2015.11.011 Fatehi, M. and Asadi, H.H., 2017. Data integration modeling applied to drill hole planning through semi-supervised learning: A case study from the Dalli Cu-Au porphyry deposit in the central Iran. Journal of African Earth Sciences, 128: 147–160. https://doi.org/10.1016/j.jafrearsci.2016.09.007 Parsa, M., Maghsoudi, A., Yousefi, M. and Sadeghi, M., 2016. Prospectivity modeling of porphyry-Cu deposits by identification and integration of efficient mono-elemental geochemical signatures. Journal of African Earth Sciences, 114: 228–241. https://doi.org/10.1016/j.jafrearsci.2015.12.007 Yousefi, M. and Nykänen, V., 2017. Introduction to the special issue: GIS-based mineral potential targeting. Journal of African Earth Sciences, 128: 1–4. https://doi.org/10.1016/j.jafrearsci.2017.02.023 Zuo, R. and Carranza, E.J.M., 2011. Support vector machine: a tool for mapping mineral prospectivity. Computers & Geosciences, 37(12): 1967–1975. https://doi.org/10.1016/j.cageo.2010.09.014}, keywords = {Mineral potential modeling,Porphyry Cu-Au mineralization,Semi-supervised learning,Support vector machine,Dehsalm}, title_fa = {مدل‌ سازی پتانسیل کانی سازی مس و طلای پورفیری با به‌ کارگیری روش یادگیری نیمه‌ نظارتی در پهنه اکتشافی دهسلم، شرق ایران}, abstract_fa = {شناسایی نواحی امیدبخش معدنی در اکتشافات ناحیه ­ای برای برنامه­ ریزی عملیات اکتشاف تفصیلی با به‌کارگیری و تحلیل داده ­های اکتشافی موجود در قالب مدل‌سازی پتانسیل معدنی توسعه‌یافته است. در این پژوهش، برای مدل‌سازی پتانسیل مس و طلای پورفیری در پهنه اکتشافی دهسلم واقع‌ در جنوب بلوک لوت، شرق ایران، از روش یادگیری ماشین بردار پشتیبان نیمه‌نظارتی استفاده‌شده است. روش­های یادگیری نیمه‌نظارتی در مرحله یادگیری، از داده­ های برچسب ­دار و بدون برچسب اکتشافی در الگوریتم محاسباتی خود بهره می­ برند. در این مقاله، با به‌کارگیری الگوریتم ماشین بردار پشتیبان نیمه‌‌نظارتی بر روی داده­ های اکتشافی منطقه دهسلم شامل داده ­های زمین­ شناسی (سنگ‌شناسی و ساختاری)، ژئوشیمی رسوبات آبراهه­ ای، تصاویر ماهواره­ای و مغناطیس هوابرد، مناطق هدف اکتشافی مس و طلای پورفیری شناسایی شد. در ادامه، نتیجه به‌کارگیری این مدل با خروجی روش ماشین بردار پشتیبان در حالت نظارت‌شده مقایسه و ارزیابی عملکرد مدل­ های تولیدشده با استفاده از نمودارهای منحنی مشخصه عملکرد سیستم و میزان تغییرات پیش­ بینی-مساحت بهبودیافته، بررسی شد. بر این اساس، مدل پتانسیل نیمه­ نظارتی عملکرد بهتری را در شناسایی اهداف اکتشافی مس و طلای پورفیری داشته است. نواحی اهداف پتانسیل شناسایی‌شده در مدل نیمه­ نظارتی، تمامی اندیس­ های معدنی شناخته‌شده در منطقه مورد بررسی را در 2/9 درصد از مساحت ناحیه مورد بررسی، به ­درستی پیش­ بینی کرده است. اهداف اکتشافی معرفی‌شده، اغلب هم‌راستا با روند گسل­ های اصلی منطقه، در راستای شمال‌غربی- جنوب‌شرقی و مرتبط با واحدهای ولکانیک نظیر ریولیت، آندزیت، داسیت و ریوداسیت هستند. نتیجه حاصل از این پژوهش نشان ­دهنده برتری روش یادگیری نیمه ­نظارتی در شناسایی نواحی هدف معدنی برای برنامه ­ریزی عملیات تفصیلی اکتشافی است.}, keywords_fa = {مدل‌سازی پتانسیل معدنی,مس و طلای پورفیری,یادگیری نیمه‌نظارتی,ماشین بردار پشتیبان,دهسلم}, url = {https://econg.um.ac.ir/article_40223.html}, eprint = {https://econg.um.ac.ir/article_40223_f83ad1d6e4e91207600189ba6d9e34e2.pdf} } @article { author = {Ahmadi Khalaji, Ahmad and Pourmohammad, Abdolsamad and Ebrahimi, Mohammad and Homam, Masoud and Esmaeili, Rasoul}, title = {Determination of physicochemical conditions and role of fluids in evolution of Geysour granitoid (eastern Gonabad), using biotite mineral chemistry}, journal = {Journal of Economic Geology}, volume = {13}, number = {1}, pages = {215-242}, year = {2021}, publisher = {Ferdowsi University of Mashhad}, issn = {2008-7306}, eissn = {2423-5865}, doi = {10.22067/econg.v13i1.84657}, abstract = {  Introduction The chemical composition of biotite in mineralization associated with granitoids and copper porphyry deposits is sensitive to several chemical and physical factors. It is also related tomagmatic and hydrothermal activities including water concentration, halogen and metal deposits, oxidation-sulfidation equilibrium, volatility (in melt-fluid-vapor equilibrium), elemental distribution relationships, and temperature and pressure of economic deposits (Webster, 1997, 2004).   Material and methods Detailed field studies have been done, and several thin sections and polished thin sections were studied by conventional petrographic methods. Thirty points of biotite grains were selected and analyzed by a CAMECA SX Five electron probe micro-analyzer with 15 kV accelerator voltage and 20 nA beam current (5 μm beam size) at the Institute of Geology and Geophysics in the Chinese Academy of Sciences (IGG-CAS). The results were processed using MICA + software (Yavuz, 2003a, 2003b).   Results and Discussion The Geysour granitoid pluton (Lower Cretaceous) consists of granodiorite, mafic microgranular enclaves, and micro-granite sill. The granodioriticrocks are mainly composed of plagioclase, quartz, K-feldspar and biotite along with accessory minerals of zircon, apatite and magnetite. Mafic microgranular enclaves are composed of quartz diorite, granodiorite and biotite granite, with fine-grained to porphyry texture and large eyes of quartz and plagioclase assemblages. The microgranite has porphyry texture with a fine-grained groundmass. Its phenocrysts are plagioclase, quartz and biotite along with accessory minerals of allanite, needle like apatite, epidote and calcite. Biotite is the only ferromagnesian mineral in theGeysour granitoid which falls into the category of real trioctahedral mica. The biotites of granodiorite and enclave samples are in group I and group of ferrous biotites. The biotitesof microgranite samples are in group I and group of magnesium biotites (Tischendorf et al., 1997). In the 10*TiO2-(FeOtot+MnO)-MgO ternary diagram (Nachit et al., 2005) all the analyzed biotites fall into the field of reequilibrated primary biotite. The formation temperatures of biotites in granodiorite, enclave and microgranite are 653-732 oC, 631-724 oC and 689-732 oC, respectively (Luhar et al., 1984; Henry et al., 2005). The mean pressure values are about 4 Kbar ​​for granodiorite and enclave and 2 Kbar for microgranite (Uchida et al., 2007). Biotites of granodioriteand enclave biotites are located on top of the NNO buffer, which correspond to biotite compositions of magnetite series magmas, and biotites ofmicrogranite lie below the NNO buffer line and within the QFM buffer range. Biotite composition based discriminant diagrams cannot be used to determine the tectonic setting of the Geysour granitoids because they are low temperature I-type granites. The mean logarithmic ratios of fH2O to fHF and fHCl, and fHF to fHCl for the rocks studied are as follows: log(fH2O/fHF)fluid=4.56, log(fH2O/fHCl)fluid=4.47 and log(fHF/fHCl)fluid=-0.53. The first two values ​​are much larger than 1 indicating that the fluids are rich in water. Also, all biotites have high angles with linear trends of log(fHF/fHCl), log(fH2O/fHCl) and log(fH2O/fHF) indicating changes in fugacity conditions and halogen content of the fluid due to wall-rock reaction (Boomeri et al., 2009). Hydrothermal fluid fugacity ratio has been calculated for biotites of granodiorite, enclaves and microgranite samples at mean temperature of 661 oC, 654 oC and 703 o C, respectively, which indicate that hydrothermal fluids are of potassic type, because the log(fH2O/fHCl) is high, the log(fHF/fHCl) is slightly negative and the log(fH2O/fHF) is lower than that of phyllic alteration (Selby and Nesbitt, 2000). Meanwhile the magmatic fluid is significantly different from porphyry-type fluids (Baldwin and Pearce, 1982; Mason and Feiss, 1979; Selby and Nesbitt, 2000).   References Baldwin, J.‌A. and Pearce, J.‌A., 1982. Discrimination of productive and nonproductive porphyritic intrusions in the Chilean Andes. Economic Geology, 77‌(3): 664–674. http://dx.doi.org/10.2113/gsecongeo.77.3.664 Boomeri, M., Nakashima, K. and Lentz, D.‌R., 2009. The Miduk porphyry Cu deposit, Kerman, Iran: A geochemical analysis of the potassic zone including halogen element systematics related to Cu mineralization processes. Journal of Geochemical Exploration, 103‌(1): 17–29. https://doi.org/10.1016/j.gexplo.2009.05.003 Henry, D.‌J., Guidotti, C.‌V. and Thomson, J.‌A., 2005. The Ti-saturation surface for low-to-medium pressure metapelitic biotites: Implications for geothermometry and Ti-substitution mechanisms. American Mineralogist, 90‌(2–3): 316–328. https://doi.org/10.2138/am.2005.1498 Luhar, J.‌F., Carmichael, I.‌S.‌E. and Varekamp, J.‌C., 1984. The 1982 Eruptions of El Chichon volcano, Chiapas, Mexico: Mineralogy and Petrology of the anhydrite-bearing Pumices. Journal of volcanology and geothermal research, 23 (1–2): 69–108. https://doi.org/10.1016/0377-0273(84)90057-XMason, D.‌R. and Feiss, P.G., 1979. On the relationship between whole rock chemistry and porphyry copper mineralization. Economic Geology, 74(6): 1506–1510. https://doi.org/10.2113/gsecongeo.74.6.1506 Nachit, H., Ibhi, A., Abia, El.-H. and Ohoud, M.B., 2005. Discrimination between primary magmatic biotites, reequilibrated biotites and neoformed biotites. Comptes Rendus Geoscience, 337‌(16): 1415–1420. https://doi.org/10.1016/j.crte.2005.09.002 Selby, D. and Nesbitt, B.E., 2000. 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Geochimica et Cosmochimica Acta, 61‌(5): 1017–1029. https://doi.org/10.1016/S0016-7037(96)00395-X Webster, J.D., 2004. The exsolution of magmatic hydrosaline chloride liquids. Chemical Geology, 210‌(1–4): 33–48. https://doi.org/10.1016/j.chemgeo.2004.06.003 Yavuz, F., 2003a. Evaluating micas in petrologic and metallogenic aspect: I—definitions and structure of the computer program Mica+. Computational Geosciences, 29‌(10): 1203–1213. https://doi.org/10.1016/S0098-3004(03)00142-0 Yavuz, F., 2003b. Evaluating micas in petrologic and metallogenic aspect: Part II—Applications using the computer program Mica+. Computational Geosciences, 29‌(10): 1215–1228. https://doi.org/10.1016/S0098-3004(03)00143-2}, keywords = {biotite,buffer,fluids,granitoid,Geysour,Gonabad}, title_fa = {تعیین شرایط فیزیکو شیمیایی و نقش سیالات در تکامل گرانیتوئید گیسور (شرق گناباد) با استفاده از شیمی کانی بیوتیت}, abstract_fa = {توده گرانیتوئیدی گیسور با سن کرتاسه پایینی از گرانودیوریت، آنکلاوهای میکروگرانولار مافیک و سیل میکروگرانیت تشکیل‌شده است. کانی‌های اصلی این سنگ‌ها عبارتند از پلاژیوکلاز، کوارتز، ارتوکلاز و بیوتیت. بیوتیت­های نمونه های گرانودیوریت و آنکلاوها در گروه I و گروه بیوتیت­ های آهن­ دار قرار دارند و بیوتیت­ های نمونه ­های میکروگرانیت در گروه I و گروه بیوتیت ­های منیزیم ­دار قرار می­ گیرند. دمای تشکیل بیوتیت ­ها در گرانودیوریت 653 تا 732 درجه سانتی‌گراد ، آنکلاو 631 تا 724 درجه سانتی‌گراد و در میکروگرانیت 689 تا 732 درجه سانتی‌گراد است. همچنین مقدار فشار متوسط برای گرانودیوریت و آنکلاو حدود Kbar 4 و میکروگرانیت Kbar 2 است. بیوتیت­ های توده گرانودیوریتی و آنکلاوها در بالای بافر NNO قرار دارند و بیوتیت ­های میکروگرانیت در زیر خط بافر NNO و در محدوده بافر QFM واقع می ­شوند. از آنجایی‌که توده گرانیتوئیدی گیسور از گرانیت ­های نوع I دما‌ پایین است، نم ی­توان از نمودارهای متمایز‌کننده محیط­ های زمین‌ساختی با استفاده از ترکیب بیوتیت ­ها استفاده‌ کرد. همه بیوتیت ­ها با روندهای خطی log(fHF/fHCl)، log(fH2O/fHCl) و log(fH2O/fHF) زاویه زیادی می­ سازند که بیانگر تغییر شرایط فوگاسیته و تغییر محتوای هالوژن سیال ­ها در اثر واکنش سنگ دیواره است. نسبت ­های فوگاسیته سیالات هیدروترمال نشان می­ دهند که سیالات هیدروترمال از نوع پتاسیک هستند؛ اما سیالات ماگمایی توده نفوذی گیسور به‌طور مشخصی متفاوت از سیالات پورفیری است.}, keywords_fa = {بیوتیت,بافر,سیالات,گرانیتوئید,گیسور,گناباد}, url = {https://econg.um.ac.ir/article_40224.html}, eprint = {https://econg.um.ac.ir/article_40224_2a68ba67310d79a64e1cf1596c4b7fdc.pdf} }