Petrological Journal

Evolution of the ore-forming fluids in the Dashkasan gold deposit, NE Qorveh, West of Iran, based on tourmaline chemical composition and fluid inclusion data

Mohammad Moradi; Zahra Alaminia; Ebrahim Tale Fazel; Mahin Mansouri Esfahani

Articles in Press, Accepted Manuscript, Available Online from 31 May 2022

https://doi.org/10.22108/ijp.2022.132378.1265

Abstract

The Dashkasan gold deposit with 52 Mt of oxidized ore reserves at mean grades of 1.77 g/t Au is hosted by porphyritic dacite/rhyodacite rocks. Tourmaline mineralization occurs as ... Read More

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Petrology, trace and rare earth elements geochemistry, and tectonic setting of basic- intermediate volcanic rocks from northwest of Nain, Isfahan

farzaneh khademian; Zahra Alaminia; Ali Ghasemi; Alireza Nadimi

Volume 13, Issue 4 , December 2022, , Pages 1-34

https://doi.org/10.22108/ijp.2023.134625.1285

Abstract

Received: 3 August 2022Accepted: 2 January 2022 KeywordsVolcanic rocksCalc-alkaline seriesEnriched mantleGarnet-lherzoliteSubduction zoneCentral part of Urumieh- Dokhtar ... Read More Received: 3 August 2022Accepted: 2 January 2022 KeywordsVolcanic rocksCalc-alkaline seriesEnriched mantleGarnet-lherzoliteSubduction zoneCentral part of Urumieh- Dokhtar zone ?????????????????????????????10.22108/ijp.2023.134625.1285 IntroductionThe magmatic evolution of the Urumieh-Dokhtar arc is related to the Neo-Tethys subduction and the continental collision between the Arabian and Eurasian plates, which has led to the creation of diverse and different magmatism along different parts of this belt (Shahabpour, 2005; Agard et al., 2011; Richards, 2015; Karimpour et al., 2021).Volcanic rocks, with various lithological compositions located in the central part of the Urumieh-Dokhtar belt, are part of the extensive Eocene activity, Knowing the nature of basic-intermediate volcanic rocks northwest of Nain requires more detailed investigations. For this purpose, the exploration areas of Chakad, Safafoulad, and Mehrando, located northwest of Nain, were selected for further investigations. The main goal of the present paper is to understand the origin and the tectonic of the volcanic rocks of this part of the Urumieh-Dokhtar magmatic belt using their petrography and geochemical characteristics. Regional GeologyMany outcrops belonging to Tertiary volcanic lavas and pyroclastic deposits are widespread 50 km northwest of Nain, within the central part of the Urumieh-Dokhtar magmatic arc (UDMA). The volcanic units are basic to acidic composition ranging in age from Eocene to Oligocene (Chiu et al., 2013) and pyroclastic rocks including tuff, breccia, and ignimbrite, low in altitude, overlain by a sequence of Quaternary alluvium. In the exploration areas of Chakad, Safafoulad, and Mehrando, the Eocene basic-intermediate volcanic rocks with the combination of basalt, basaltic-andesite and pyroclastic rocks exposed and play as the host rocks for copper mineralization. The youngest igneous units observed in the region are a set of parallel diabase and dolerite dikes as swarms, intruded the volcanic rocks. Based on field observations, silica and carbonate veins with different trends are observed along with copper mineralization in basaltic- andesite and basalt units. This ore mineralization occurs mainly as an oxide (malachite and azurite) accompanies with propylitic alteration and less argillic and silicification along and at the intersection of faults and fractures.Materials and methodsFollowing the preparation of thin sections and petrographic and mineralogical investigations of these units, 26 volcanic samples have been analyzed by the ICP-MS method for trace and rare earth elements.Petrography The basic-intermediate volcanic rocks of the region are mostly basalt and basaltic-andesite, as well as diabase and dolerite dikes. The studied basalts, mineralogically, dominated by Euhedral to subhedral phenocrysts of plagioclases (30 to 50 vol%) and clinopyroxene phenocrysts, with porphyritic texture. Small amounts of olivine occur as phenocryst and iddingsite basaltic- andesite consists of plagioclase (40 to 60 vol%), and clinopyroxene (15 to 20 vol%) phenocrysts set in a fine-grained to microlithic groundmass. Clinopyroxene and plagioclase with intergranular texture are the dominant minerals in diabase and dolerite. Chlorite, calcite, epidote, and quartz are the main altered minerals of the rocks under study.Discussion and ConclusionBased on the geochemical data, the basic- intermediate volcanic rocks with the combination of basalt and basaltic- andesite have a calc-alkaline nature, consistent with the features of volcanic arcs in the subduction zone of the active continental margin. In the primitive mantle-normalized multi elements diagram, the patterns of basic- intermediate volcanic rocks show enrichment of LILE (e.g., Ba, K, Rb) and depletion of HFSE (e.g., Nb, Ti, Zr) one of the remarkable features of subduction zone- related magmas (Yang and Li, 2008; Kuscu and Geneli, 2010). In the chondrite-normalized REEs diagram, these rocks exhibit LREE enrichment relative to HREEs. Rare earth elements such as La and Sm are not significantly affected by the mineralogical changes of the source rock, so they can provide information on the chemical composition of the total source rock. The volcanic rocks of the region generated by partial melting of 5 to 10% (Aldanmaz et al., 2006) of the enriched garnet- lherzolite mantle at a depth of 90 to 100 km. It seems that the parent magma has been metasomatized under the influence of fluids and sediments derived from the oceanic lithosphere. As the tectonic setting identification diagrams display the studied samples plotted in the range of magmas related to the subduction zone of the active continental margin. The magmatism under discussion, is the result of the subduction of the Neo-Tethys oceanic lithospheric beneath the central Iranian plate which have given rise to great magmatism during the Eocene and following it.AcknowledgmentsThe authors are very grateful to the esteemed referees of Petrology magazine for their valuable suggestions in improving the scientific structure of the article

Investigation of the geochemical and mineralogical characteristics of the dikes associated with copper mineralization at the southeastern Ardestan (NE Isfahan)

Maryam Salehi; Zahra Alaminia; Mahin Mansouri Esfahani

Volume 8, Issue 30 , September 2017, , Pages 81-98

https://doi.org/10.22108/ijp.2017.81992

Abstract

The Ardestan study area lies in the northeast of Isfahan and at the outer margin of Urumieh -Dokhtar Volcanic Arc (UDMA). In this area, copper mineralization is associated with dikes. ... Read More

Cu mineralization and geochemical haloes characteristics of Garmab district (eastern Semnan)

Zahra Alaminia; Mohammad Sharifi

Volume 6, Issue 24 , January 2016, , Pages 23-38

Abstract

The Garmab Cu mineralization, in the east of Semnan and southeast of Shahroud, is situated in the Eocene conglomerate association with weakly hydrothermal altered. The weak alteration, ... Read More

Geochemistry and geochronology of Upper Cretaceous, magnetite series granitoids, Arghash-GhasemAbad, NE Iran

Zahra Alaminia; Mohammad Hassan Karimpour; Seyed Massoud Homam; Fritz Finger

Volume 3, Issue 12 , March 2013, , Pages 103-118

Abstract

The Arghash gold prospect occurs in the northeastern of Central Iranian domain. It is located in Sabzevar zone, north of Darouneh fault. The exposed rocks in the study area consist ... Read More

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Author = Alaminia, Zahra

Evolution of the ore-forming fluids in the Dashkasan gold deposit, NE Qorveh, West of Iran, based on tourmaline chemical composition and fluid inclusion data

Abstract

Petrology, trace and rare earth elements geochemistry, and tectonic setting of basic- intermediate volcanic rocks from northwest of Nain, Isfahan

Abstract

Investigation of the geochemical and mineralogical characteristics of the dikes associated with copper mineralization at the southeastern Ardestan (NE Isfahan)

Abstract

Cu mineralization and geochemical haloes characteristics of Garmab district (eastern Semnan)

Abstract

Geochemistry and geochronology of Upper Cretaceous, magnetite series granitoids, Arghash-GhasemAbad, NE Iran

Abstract