Petrology
Jalil Ghalamghash; Meysam Akbari; Reza Jamal
Abstract
The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate ...
Read More
The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran-Chagai subduction zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate inclusions enclosed by acidic groundmass, and disequilibrium textures in plagioclase phenocrysts including sieve texture, zoning, and dissolution margin, which may reflect magma mixing. These rocks record high-K calc-alkaline to calc-alkaline affinity with enrichment in LREE and LILE relative to HREE and HFSE, respectively. These features, coupled with the clear depletion in HFSE (such as Nb, Ta, and Ti) are consistent with typical subduction-related volcanic arcs. Taftan primary melts might have been produced by ~15% partial melting of spinel lherzolite mantle. The normalized multi-element patterns which mimic the upper continental crust values, and enrichment in Pb, Th, U, and Rb agree well with magma evolution by assimilation and fractional crystallization (AFC). The available isotopic geochronology dataset reveal that the youngest volcanoes of the Makran-Chagai magmatic arc are Bazman and Kuh-e-Sultan volcanoes. A geochemical comparison of these volcanoes highlights that magmatism in the Taftan where the crust is thick, underwent a higher degree of crustal assimilation en route to the surface.
Petrology
hojjat hajhassani; Jalil Ghalamghash; Mansour Vousoughi Abedini; Rahim Dabiri; Hamideh Rashid
Abstract
The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They ...
Read More
The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They show enrichments of LREEs relative to HREEs and LILE relative to HFSE with negative anomalies in Nb, Ta and Ti, in normalized trace element diagrams. The leucocratic granite of the Alvand batholith resemble A-type and can be further classified in two of A and A' types granite. The trace elements content of A-type is much higher than A'-type granite. Based on geochemical data, it seems that A- and A'-type granites were generated from partial melting of mantle source. As mantle magma ascends, fractionate and empalce into the crust, A-type leucocratic are formed with minimal contamination and A'-type leucocratic with significant contaminant with continent crust are formed. Field and geochronology data suggest that the leucocratic granite were generated in the late Jurassic, which is contemporaneous with the subduction of the Neo-Tethys oceanic crust beneath the central Iran. It seems that the leucocratic granites were emplaced during a local extensional phase as dykes and small bodies in the Alvand batholith.
Petrology
J. Ghalamghash; Sara Houshmand; Sayad Jamal Shaikhzakariaee; Hamideh Rashid
Abstract
The Kharsare intrusive mass (South of Ghorveh) is located in the middle part of the Sanandaj–Sirjan zone. The batholith comprises three plutonic units including gabbro- diorite, granite and syenite. In addition, the hybrid rocks with a lot of mixing and minling evidences (including lobate or/and ...
Read More
The Kharsare intrusive mass (South of Ghorveh) is located in the middle part of the Sanandaj–Sirjan zone. The batholith comprises three plutonic units including gabbro- diorite, granite and syenite. In addition, the hybrid rocks with a lot of mixing and minling evidences (including lobate or/and ellipsoidal micro granular mafic enclaves sometimes with chilled margins in granite or in hybrid rocks; net-veining granite; and synplutonic brecciated mafic dikes) crop out in interaction zone between granites and gabbros. The calc-alkaline and metaluminous gabbro-diorite and High-K calc-alkaline and peraluminous granites emplaced in Late Jurassic, simultaneously. The peraluminous A-type syenite formed later and intrude two above mentioned plutonic rocks. Geochemical features suggest that gabbro-diorites and granites formed in an active continental margins. It seems the pioneer mafic magma formed in a subduction setting by partial melting of metasomatized mantle. It ascent and emplace in lower crust to produce the granitic melt. The mingling and mixing evidences that may support local crustal contamination of the mafic melt. The younger syenite is resulted from heating by intrusion of the mafic magma in the end phase of continental arc magmatism.
Petrology
Sanaz Yajam; jalil Ghalamghash
Abstract
The easts Sanadaj- Galali plutons of the northern Sanandaj-Sirjan Zone, Zagros Orogeny, are composite, polyphase bodies that generated during subduction of Neotethys beneath the Eurasian plate. A-type magmatism in this area presents by Alkaline, high K, ferroan leucogranites. Despite having mineralogical ...
Read More
The easts Sanadaj- Galali plutons of the northern Sanandaj-Sirjan Zone, Zagros Orogeny, are composite, polyphase bodies that generated during subduction of Neotethys beneath the Eurasian plate. A-type magmatism in this area presents by Alkaline, high K, ferroan leucogranites. Despite having mineralogical and isotopic similarities, these leucogranites show a clear division, based on the geochemical and SHRIMP zircon crystal dating results. Qalaylan leucogranite with the crystallization age of 159 ± 3Ma is A1-type. Other leucogranites are A2-type and crystalized about 20 million years later (140-149 Ma). In fact, mantle derived mafic magma, as heat source, caused partial melting of heterogeneous pre-fertilized Sanadaj-Sirjan basement and creates Qalaylan leucogranites. Younger leucogranites are A2-type and present different evolution path. These rocks generate in a post collisional setting as a result of partial melting of heterogeneous pre-fertilized Sanadaj-Sirjan basement, about 20 Ma later. In post collisional setting, asthenosphere upwelling do to the slab roll back or slab steepening could be a heat source of crust melting and generates the younger leucogranites.
K Shiaian; J Ghalamghash; M Vosoughi Abediny; F Masoudi
Abstract
The Bazman volcano is located in the Makran Magmatic Arc. The pyroclastic rocks and lava with rhyodacitic to basaltic composition and calc-alkaline affinities erupted from the central and lateral craters of this volcano during the Quaternary period. The primitive mantle normalized Multi-elements diagrams ...
Read More
The Bazman volcano is located in the Makran Magmatic Arc. The pyroclastic rocks and lava with rhyodacitic to basaltic composition and calc-alkaline affinities erupted from the central and lateral craters of this volcano during the Quaternary period. The primitive mantle normalized Multi-elements diagrams show a relatively high abundance of LIL relative to HFS incompatible elements with negative anomalies of Nb and Ti. Their chondrite–normalized REE patterns are slightly enriched in LREE relative to HREE with negative Eu anomalies. These geochemical features suggest that the volcanic rocks of bazman formed in a subduction setting by partial melting of metasomatized mantle. On the base of La/Yb vs Dy/Yb and La/Sm vs Sm/Yb diagrams the sources of the magmas is phlogopite-spinel-lherzolite or/and phlogopite-garnet- lherzolite.
A Aslani; H Alimohammadian; J Ghalamghash; H Nazari
Abstract
The studied locality covers an area of 120 km2, located at south and southwest of the Hamedan city. The porphyritic granite is the dominant volume of this intrusive body. This granitoid is divided into the granites (monzogranites, syenogranites and alkali feldspar granites) and granodiorites from petrographic ...
Read More
The studied locality covers an area of 120 km2, located at south and southwest of the Hamedan city. The porphyritic granite is the dominant volume of this intrusive body. This granitoid is divided into the granites (monzogranites, syenogranites and alkali feldspar granites) and granodiorites from petrographic point of view. The major part of the study area have magmatic-sub-magmatic fabric and few of the samples show high temperature solid state deformation with presence of chess-board quartz, bending and kink band of biotite and mineral size decreasing from microstructural point of view. The total numbers of 450 oriented core samples were collected from 107 stations, to study the anisotropy of magnetic susceptibility. The total average susceptibility for all samples were 114-314 µSI and the mean susceptibility (Km) of granodiorites was 457.5 µSI, and it ranges from 282-633 µSI, which is higher in compare to granites. This difference is due to the presence of magnetite grains in granodiorites, which has been proved by heavy mineral analysis. The magnetite comprises 0.01-0.025 % of total volume in these rocks. The Km normally varies from 14-514 µSI and indicates the paramagnetic type of granites. The P values vary from 0.72-7.4 %. The T values in most of the samples is positive (T>0) and show planer nature of most of the intrusive body. The high degree of dipping of magnetic foliation and lineation at the central part of the intrusive body, which decreases with increasing distance from center of the intrusive body, may indicate the location of feeding. This characterization can be seen at two other places addition to the center. On the basis of magnetic parameter and other factors such as dominant transpression tectonic regime in this area, one can say that the ascending magma was due existing of stretching environment with NW-SE trend, and this can be proved by direction of magnetic lineations at the same direction. The differences in the direction of NE-SW, which some of the studied sites show, may be due to rotation of magnetic body during injection and emplacement in response to prevailing tectonic forces in studied area and viscosity of magma.
J Ghalamghash; R Chaharlang
Abstract
The Late Miocene- Quaternary volcanoes including Sahand, Ararat, Nemrut, Suphan, Tendurek and Lesser Caucasus volcanoes in the Arabia-Eurasia collision zone, are studied in this paper. The volcanoes have been erupted pyroclastic materials and lava flows with basaltic to rhyolitic composition, in several ...
Read More
The Late Miocene- Quaternary volcanoes including Sahand, Ararat, Nemrut, Suphan, Tendurek and Lesser Caucasus volcanoes in the Arabia-Eurasia collision zone, are studied in this paper. The volcanoes have been erupted pyroclastic materials and lava flows with basaltic to rhyolitic composition, in several times. These volcanic rocks have calk-Alkaline (Sahand) to Alkaline nature (Tendurek). The Nb, Ta, Ti and Y depletions in accompanied with Rb, Ba, K, Sr and Th enrichments are the common geochemical features of these volcanic rocks in primitive mantle normalized multi element diagrams. In addition, enrichment of LREE relative to HREE in chondrite–normalized REE patterns is visible in all volcanic rocks of the regions. The enrichment of LREE and depletion of HREE in Sahand and Lesser Caucasus volcanic rocks is implying that their magma is derived from fraction melting of garnet-lherzolite of mantle source. In contrast, the volcanoes of eastern Anatolia melted from spinel-lherzolite rocks of mantle. The negative Nb, Ta anomalies in primitive mantle normalized multi element diagrams of volcanic rocks indicate geochemical features of Pre-collision subduction component in parental magma of studied volcanoes. High contents of La, Th, Ce and Rb indicate magma contamination during parental magma emplacement in crust accompanied with assimilation, fractional crystallization process.
Y Bayati-Rad; H Mirnejad; J Ghalamghash
Abstract
Gol-Gohar mining complex, located southwest of Sirjan (KermanProvince) and within the Sanandaj-Sirjan structural zone, has a number of iron-rich deposits that provides 30% of steel demand in the country. The main ore in this deposit is magnetite with subordinate amounts of hematite and accessory pyrite ...
Read More
Gol-Gohar mining complex, located southwest of Sirjan (KermanProvince) and within the Sanandaj-Sirjan structural zone, has a number of iron-rich deposits that provides 30% of steel demand in the country. The main ore in this deposit is magnetite with subordinate amounts of hematite and accessory pyrite and chalcopyrite phases. Comparison of rare earth element (REE) distribution patterns of Gol-Gohar magnetite with those of magmatic magnetite (Kiruna) and also magnetite associated with granite and basalts show similar enrichment in light REE relative to the heavy REE and negative Eu anomaly. Such features can also be observed in apatite from Kiruna, Iron Spring, Choghar and Esfordi Fe ore deposits, the origin of all of which have been ascribed as magmatic due to a lack REE distribution patterns similar to phosphorites. Based on these characteristics, it seems that the magnetite in Gol-Gohar Fe deposit has dominantly originated from a magmatic fluid.
J Ghalamghash; S. Houshmand Manavi; M. Vousoughi Abedini
Abstract
Oshnavieh Plutonic Complex (OPC), hosted within the northernmost part of the Sanandaj- Sirjan zone, allows distinguishing three suites including diorite, granite and alkalisyenite-alkaligranite (AS-AG). Dioritic rocks formed from partial melting of enriched lithospheric mantle sources on base of minerlogical ...
Read More
Oshnavieh Plutonic Complex (OPC), hosted within the northernmost part of the Sanandaj- Sirjan zone, allows distinguishing three suites including diorite, granite and alkalisyenite-alkaligranite (AS-AG). Dioritic rocks formed from partial melting of enriched lithospheric mantle sources on base of minerlogical and geochemistry. The granite suite is S type that formed from partial melting of metapelitic-greywacke source. The peraluminous A-type granite of AS-AG suite are generated by partial melting of quartzo-feldspatic source at high temperatures. According to the negative Nb, Ta and Ti anomaly in spider diagrams, and tectonic discrimination diagram of Rb-(Y+Nb), the diorite suite formed in active continental margin (VAG) environment. According to the diorite’s formed environment and simultaneously formed granite in 100 M.a., OPC seems to have formed by northeastward subduction of Neo-tethyan oceanic crust under the Iranian continental crust. Following intrusion and setting of mafic magma into the crust, partial melting of pelitic-greywacke, resulted from heating by intrusion of the mafic magma, produced the granitic magma. After 20 Ma the AS-AG suite formed from melting of quartzo-feldspatic rocks of lower crust, probably by heating of mafic magma and/or in relaxation period of subduction and emplaced in the continental volcanic arc.
M. Advay; A. Jahangiri; M. Mojtahedi; J. Ghalamghash
Abstract
The study area as a part of Maku-Tabriz zone is located in about 20 km NE of Khoy, NW Iran. Shah Ashan Dagh granite covers about 60 km2 of the area and emplaced into Permian host rocks and covered by Oligo-Miocene sedimentary rocks (Qom Formation). The Shah Ashan Dagh intrusive rocks composed of gabbro ...
Read More
The study area as a part of Maku-Tabriz zone is located in about 20 km NE of Khoy, NW Iran. Shah Ashan Dagh granite covers about 60 km2 of the area and emplaced into Permian host rocks and covered by Oligo-Miocene sedimentary rocks (Qom Formation). The Shah Ashan Dagh intrusive rocks composed of gabbro and alkali-feldspar granite. Porphyric and granophyric textures indicate shallow depth emplacement and perthitic texture shows hypersolvous nature of this body. The studied mafic rocks have high LREEs relative to HREEs and they indicate relatively enrichment of LILEs and depletion in HFSEs (exception Hf, Ta, Nb). The studied mafic rocks based on positive Nb and Ta anomalies show similarity to plum type MORB. These rocks are tholeiitic and they have mantle plum enriched source. Shah Ashan Dagh granite characterized with high-K, sub-alkaline, metaluminous to peraluminous and weakly peralkaline nature. They have high content of LILEs, especially Th and Rb, and low content of Eu, Sr, Ta, Nb, Ba, and Ti, implying the granites may have been derived from crustal melts.
