Mineral chemistry and P-T conditions of the adakitic rocks from Torud–Ahmad Abad magmatic belt, S-SE Shahrood, NE Iran

Yousefi, Fazilat; Sadeghian, Mahmoud; Wanhainen, Christina; Ghasemi, Habibollah; Papadopoulou, Lambrini; Bark, Glenn; Rezaei-Kahkhaei, Mehdi; Koroneos, C.

doi:10.1016/j.gexplo.2017.09.006

Cited by 5 publications

(15 citation statements)

References 26 publications

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“…Their composition ranges from Mg-hastingsite to Mg-hornblende. Pyroxenes range in composition from diopside to augite (Yousefi et al, 2017b). The studied rocks display porphyritic, glomeroporphyritic, granular and trachytic textures.…”

Section: Petrographymentioning

confidence: 99%

“…Based on previous studies, the composition of the hypabyssal rocks in Torud-Ahmad Abad are andesite, dacite and basaltic andesite (Yousefi et al, 2017a). The mineral assemblages and the composition of minerals in magmatic rocks are related to the composition and evolving conditions of the melt during crystallization (Yousefi et al, 2017b). In these rocks, accumulated ferromagnesian minerals, especially hornblende and pyroxene, occur in the form of enclaves and micro-enclaves (mafic clots).…”

Section: Introductionmentioning

confidence: 99%

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Plagioclase Hosted Melt Inclusion in Hypabyssal Rocks in Torud-Ahmad Abad Magmatic Belt

Yousefi¹,

Παπαδοπούλου

Sadeghian³

et al. 2019

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This study investigates for the first time melt inclusions (MI) that are found within fundamental minerals of subvolcanic rocks in Torud-Ahmad Abad magmatic belt. The Torud-Ahmad Abad magmatic belt is situated in south-southeast of Shahrood and belongs to the northern part of central Iran structural zone. Melt inclusions represent liquids that were trapped along growth zones (primary) or healed fractures of mineral phases, which crystallized from the silicate liquid as it cooled. Based on SEM analysis of these melt inclusions, their compositions are dacite, andesite and basaltic andesite. Thus, with the use of melt inclusions in the volcanic rocks of Torud-Ahmad Abad magmatic belt, we attempt to show the compositional evolution and origin of magma. The effective factors on magma evolution are magma mixing, fractional crystallization and crustal contamination. Περίληψη Σε αυτή την εργασία, εξετάζονται για πρώτη φορά, τα εγκλείσματα τήγματος (melt inclusions -MI) που φιλοξενούνται μέσα στα ορυκτά συστατικά των υποηφαιστειακών πετρωμάτων της μαγματικής ζώνης Torud-Ahmad Abad, νότια-νοτιοανατολικά του Shahrood (στο βόρειο τμήμα της τεκτονικής ενότητας του κεντρικού Ιράν). Τα Volume 55 εγκλείσματα τήγματος αντιπροσωπεύουν ρευστά που εγκλωβίστηκαν κατά τη διάρκεια της ανάπτυξης των ζωνών (πρωτογενής) ή κατά την επούλωση ρωγμών των ορυκτών φάσεων, οι οποίες κρυσταλλώθηκαν από ένα πυριτικό τήγμα κατά τη διάρκεια της ψύξης. Αυτά τα εγκλείσματα τήγματος, με βάση τις αναλύσεις SEM, αντιστοιχούν σε σύσταση δακίτη, ανδεσίτη και βασαλτικού ανδεσίτη. Έτσι, με την χρήση των εγκλεισμάτων τήγματος των ηφαιστειακών πετρωμάτων της μαγματικής ζώνης Torud-Ahmad Abad, φαίνεται η εξέλιξη και η προέλευση του μάγματος. Οι παράγοντες που συνέβαλαν στην εξέλιξη αυτών των μαγμάτων είναι η μίξη μαγμάτων, η κλασματική κρυστάλλωση και η μόλυνση από τον φλοιό. Λέξεις κλειδιά: εγκλείσματα τήγματος, υποηφαιστειακά πετρώματα, εξέλιξη μάγματος, μαγματική ζώνη Torud-Ahmad Abad.

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Section: Petrographymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plagioclase Hosted Melt Inclusion in Hypabyssal Rocks in Torud-Ahmad Abad Magmatic Belt

Yousefi¹,

Παπαδοπούλου

Sadeghian³

et al. 2019

geosociety

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“…The association of these hypabyssal magmatic rocks and melting Neo‐Tethys oceanic plate has been widely accepted by researchers (Ghasemi & Rezaei Kahkhaei, 2015; Jamshidi et al, 2015; Yousefi, Sadeghian, Samyari, & Ghasemi, 2017; Yousefi, Sadeghian, Wanhainen, et al, 2017). According to geothermobarometry of some phenocrysts, such as amphibole, plagioclase, and pyroxene, in these adakites in some of these regions, the depth of the beginning of magma crystallization (before shallow emplacement) is estimated to be <30 km (Jamshidi et al, 2015; Yousefi, Sadeghian, Wanhainen, et al, 2017). Our focus is on the three neighbouring areas, where magmatism occurred, that is, Sabzevar, Qouchan‐Esfarayen, and south to southeast Shahrood.…”

Section: Introductionmentioning

confidence: 99%

“…Also Maghdour‐Mashhour, Esmaeily, Shabani, Chiaradia, and Latypov (2015) have pointed to volcanic and plutonic rocks that outcrop in central (Urumieh–Dokhtar Magmatic Assemblage, UDMA) and north–northeastern Iran (Alborz Magmatic Belt, AMB); they proposed that this magmatism marked the beginning of subduction of the Neo‐Tethyan oceanic lithosphere beneath the south–southwestern border of the Turkish–Iranian high plateau and was approximately simultaneous with the closure of Palaeotethys in southern Eurasia during the Late Permian–Early Triassic. In several parts of the Central Iran Structural Zone (CISZ), there are numerous intrusions with intermediate to felsic compositions with adakitic geochemical signatures (Gardideh, Ghasemi, & Sadeghian, 2018; Jamshidi, Ghasemi, Miao, & Sadeghian, 2018; Jamshidi, Ghasemi, Troll, Sadeghian, & Dahren, 2015; Yousefi et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Adakitic rocks in northeast Iran usually are exposed as dikes, small outcrops representing hypabyssal domes, and small intrusions (stocks to plutons) (Figure 1). The specific focus of this analysis is magmatism in the northern part of the CISZ, which includes smaller magmatic belts, such as Torud–Ahmad Abad, Abbas Abad–Davarzan‐Sabzevar, and Qouchan–Esfarayen (Yousefi, 2017; Yousefi, Sadeghian, Samyari, & Ghasemi, 2017). These areas have also been mentioned by Jamshidi et al (2015) and Gardideh et al (2018), where recent research has been carried out in these regions as well.…”

Section: Introductionmentioning

confidence: 99%

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Petrology, petrogenesis, and geochronology review of the Cenozoic adakitic rocks of northeast Iran: Implications for evolution of the northern branch of Neo‐Tethys

et al. 2020

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Cenozoic adakitic rocks of the northern part of the Central Iran Structural Zone (CISZ) are among the notable geological features of the terrains in northeast Iran, so a comprehensive comparison of several of these adakitic sequences is presented. This lithogeochemical analysis is constrained to examining adakitic magmatism of the three magmatic belts within the CISZ, which from southeast to northeast and from oldest to youngest are as follows: (a) south of Shahrood‐Damghan, (b) north‐northwest of Sabzevar‐Neyshabour, and (c) south of Qouchan and west of Esfarayen. Radiogenic isotope analysis using Rb–Sr and Sm–Nd methods show that the adakitic rocks associated with Qouchan‐Esfarayen magmatism have 0.512581 to 0.51288 initial 143Nd/144Nd and 0.703903 to 0.705627 initial 87Sr/86Sr, with εNd −0.86 to 4.98. Adakitic rocks in south to southeast Shahrood have 0.512775 to 0.512893 initial 143Nd/144Nd and 0.703746 to 0.705314 initial 87Sr/88Sr, with εNd 3.69 to 6.0, and adakites emplaced into the Sabzevar ophiolite have 0.512846 to 0.512911 initial 143Nd/144Nd and 0.70379 to 0.705019 initial 87Sr/86Sr contents with εNd of 5.26 to 6.54. Isotopic initial ratios of Nd and Sr support an origin involving partial melting of the subducting oceanic lithosphere of the northern branch of Neo‐Tethys and the associated suprasubduction mantle wedge in producing these adakitic rocks.

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Geochemical and Nd-Sr Isotopic Compositions of Hypabyssal Adakites in the Torud-Ahmad Abad Magmatic Belt, Northern Central Iran Zone: Analysis of Petrogenesis and Geodynamic Implications

et al. 2021

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Eocene intermediate to felsic subvolcanic rocks of the Torud-Ahmad Abad magmatic belt (TAMB), in the northern part of the Central Iran zone, are exposed between the Torud and Ahmad Abad regions in South-Southeast Shahrood. These igneous rocks include hypabyssal dacite, trachyte, andesite, trachy-andesite, and basaltic andesite; they are mainly composed of phenocrysts and microcrystalline groundmass of pyroxene, amphibole, and plagioclase, with minor biotite and titanomagnetite; they form domal structures (plugs and stocks), dikes, and sills that intruded into Neoproterozoic to cogenetic Eocene volcano-sedimentary sequences. Based on isotopic analysis of these intermediate to acidic rocks, initial ratios of 143 Nd/ 144 Nd range from 0.512 775 to 0.512 893 and initial ratios of 87 Sr/ 86 Sr range from 0.703 746 to 0.705 314, with quite positive ɛ Nd(i) values of +3.69 to +6.00. They are enriched in light rare earth elements and large ion lithophile elements and depleted in heavy rare earth elements and high-field strength elements, the SiO 2 content is (52-62) wt.%, and Na 2 O content >3 wt.%, Al 2 O 3 content >16 wt.%, Yb <1.8 ppm, and Y <18 ppm. These geological, geochemical, and Sr and Nd isotopic data are consistent with adakitic signatures originating by partial melting of the subducted Neo-Tethys oceanic slab (Sabzevar branch) and lithospheric suprasubduction zone mantle. The mantle signatures typifying the rapidly emplaced adakitic rocks (slab (high-silica adakite) and suprasubduction zone (low-silica adakite) melts) together with their locally voluminous extent are evidences that support a locally extensional geodynamic setting; and the evidence is consistent with an evolution to local transpression in the Late Eocene in this convergent margin arc environment to rifting (basalts to adakites) towards submarine conditions in the Neogene. KEY WORDS: isotope geochemistry, adakite rocks, Central Iran zone, Shahrood, Iran.

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Mineral chemistry and P-T conditions of the adakitic rocks from Torud–Ahmad Abad magmatic belt, S-SE Shahrood, NE Iran

Cited by 5 publications

References 26 publications

Plagioclase Hosted Melt Inclusion in Hypabyssal Rocks in Torud-Ahmad Abad Magmatic Belt

Plagioclase Hosted Melt Inclusion in Hypabyssal Rocks in Torud-Ahmad Abad Magmatic Belt

Petrology, petrogenesis, and geochronology review of the Cenozoic adakitic rocks of northeast Iran: Implications for evolution of the northern branch of Neo‐Tethys

Geochemical and Nd-Sr Isotopic Compositions of Hypabyssal Adakites in the Torud-Ahmad Abad Magmatic Belt, Northern Central Iran Zone: Analysis of Petrogenesis and Geodynamic Implications

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