Petrology
Saeid Samarbakhsh; Mohammad Hashem Emami; Seyed Mojtaba Mortazavi; Mansour Vosoughi-Abedini
Abstract
The study area, situated 50 km north of Ghaemshahr, structurally belongs to the Central Alborz tectonic zone. The volcanic rocks of the area, including basalt, andesite, trachyandesite, and dolerite are the products of fractional crystallization and some contamination processes. Clinopyroxene, olivine, ...
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The study area, situated 50 km north of Ghaemshahr, structurally belongs to the Central Alborz tectonic zone. The volcanic rocks of the area, including basalt, andesite, trachyandesite, and dolerite are the products of fractional crystallization and some contamination processes. Clinopyroxene, olivine, and plagioclase are the main minerals of these rocks. Porphyritic to mega-porphyritic texture with microlithic, glomeroporphyritic, and amygdaloidal matrix are observed in these rocks. Plagioclase, hornblende, and pyroxene can be considered the main mineral phases of these rocks. The rocks are enriched in LIL and LREE elements and depleted in HFS elements. The ratios of trace elements and rare earth elements in the studied region indicate that the basalts were formed by melting a garnet bearing peridotite at great depths and pressures. Negative Ce anomaly, Nb negative anomaly, Pb positive anomaly the role of continental lithosphere in contaminating the magmatic sources of volcanic rock in the study area. The Pb/Ce ratio similar to ocean island basalt (OIB) sources, induces OIB sources, the asthenospheric mantle, in the initial formation of basaltic magma. it can be concluded that the volcanic rocks of the area have formed in an intra-plate environment in an extensional regime.
Petrology
Nasim Askari; reza Zarei Sahamieh; Jafar Omrani; Mohamad Heshem Emami; C., Vaccaro; J. F. Santos
Abstract
Zarrin Mafic dikes, which outcrop in the Western Yazd block, Central Iran, trending NW–SE, emplaced into the Zarrin granitoid. They are sub-alkaline gabbro; characterized by intergranular and mylonitic foliated texture. Geochemical data reveal the Zarrin mafic dikes are from the partial melting ...
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Zarrin Mafic dikes, which outcrop in the Western Yazd block, Central Iran, trending NW–SE, emplaced into the Zarrin granitoid. They are sub-alkaline gabbro; characterized by intergranular and mylonitic foliated texture. Geochemical data reveal the Zarrin mafic dikes are from the partial melting lithospheric mantle, a spinel-peridotitic source. Furthermore, they are characterized by 87Sr/86Sr ratio of (0.7044-0.7028) and 144Nd/143Nd ratio of (0.5123- 0.5122), that consistent with the derivation from a lithospheric mantle. Their primitive mantle normalized trace elemental patterns display enrichment in LILEs compared to HFSEs, and positive Rb, Ba, and U but negative Ta, Nb, Th, and Zr anomalies, carrying characteristics subduction-related magmatism and metasomatism by subduction-related fluids. The petrogenesis of the Zarrin mafic dikes are related to melting of the lithospheric mantle, and upwelling asthenospheric mantle in the extensional basin which was associated with the subduction.
Economic Geology
Sahar Tarabi; Mohamad Hashem Emami; Sourosh Modaberi; Seyed Jamal Shaykh Zakariaee
Abstract
Momen-abad area, in the southeast of Birjand and the northeast of Sarbisheh, is located in the Sistan-Zemestan zone. Based on the field studies, petrography, geochemical (XRF) and X-ray diffraction (XRD) in two volcanic sequences, the alteration conditions in the area have been investigated. According ...
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Momen-abad area, in the southeast of Birjand and the northeast of Sarbisheh, is located in the Sistan-Zemestan zone. Based on the field studies, petrography, geochemical (XRF) and X-ray diffraction (XRD) in two volcanic sequences, the alteration conditions in the area have been investigated. According to mineralogy and chemical studies, bentonites are sodium-calcium and heterogeneous. Mineralogy findings indicate that smectite minerals, cristobalite and quartz, alkaline feldspars (albite and anorthite and sanidine), gypsum, calcite, hematite, holandite, klinoptiolite, kaolinite, ileite, and halite minerals form bentonites. In the first sequence, the effects of argillic and iron oxide alterations and in the second sequence, the effects of alteration of argillic, carbonate, chlorite, calcite, albite, silicification and iron oxide are found. Altered units which are related to the second sequence in four layers include Rhyolytic perlites of the vein, masses, lenses; white bentonites and green; Rhyodacite and dacite with the effects of alteration of devitrification, and the alteration of perlite to bentonite, advanced argillic and silicification. In addition, the composition textures of lava-pyroclastic, devitrification and the alteration of perlite to bentonite due to diagenetic alteration are found out. Glass argillization and feldspars in volcanic units, and the alteration of plagioclase to albite + sericit, biotite to chlorite, stone to quartz, calcite, zeolite and chlorite in perlites, iron oxide veins and red unit are found out in the sequences. Moreover, the change color of bentonite in the region related to alteration hydrothermal, and the presence of fluids and iron-magnesium-rich solutions are obvious in these sequences.
somaye kazemi koohbanani; seyed jamal sheikh zakariai; mohammad hashem emami; Rahim Dabiri
Abstract
KoheSiah volcanic complex is in north east of Qorveh in the Kurdistan province and in Sanandaj-Sirjan zone.The age of the studied region rocks are related to the quaternary time. Set volcanic cone with a crater that has been identified as unspecified and are an average height of 2157 meters above sea ...
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KoheSiah volcanic complex is in north east of Qorveh in the Kurdistan province and in Sanandaj-Sirjan zone.The age of the studied region rocks are related to the quaternary time. Set volcanic cone with a crater that has been identified as unspecified and are an average height of 2157 meters above sea level. The composition of volcanic rocks varies from basaltic composition, Basalitic andesites, andesite and , trachyandesite. On the basis of mineral chemistry the amphiboles are classified as calcic (magnesio-hornblende). Plagioclases vary from andesine-oligoclase to labradorite. Al-barometer accounts that the pressure of amphibole crystallization is 3.2 to 6.65 Kbar and Altotal versus Fetotal/(Mg+Fetotal) accounts the pressure between 4.5 to 7 Kbar. Hornblende - plagioclase thermometer shows 464 to 473 °C for equilibrium of these two minerals and biotite thermometer shows 500 to 650 °C for biotite in andesites. The estimated oxygen fugacity imply an oxidation magma (confirms iron oxide and enrichment of Mg in amphibole)
Petrology
mozhgan Taheri; afshin ashjaardalan; Mohammad hashem Emami; Seyed Jamal Shaikh Zakariay
Abstract
Abstract In the west and south-west part of Salafchegan near Zavarian village in Iran (In central Iranian volcano plotonic belt) there are some Plutonic rocks. Based on petrography and geochemistry findings these Plutonic rocks are Diorite, Monzonite and less Quartz monzonite. The main texture in Dioritic ...
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Abstract In the west and south-west part of Salafchegan near Zavarian village in Iran (In central Iranian volcano plotonic belt) there are some Plutonic rocks. Based on petrography and geochemistry findings these Plutonic rocks are Diorite, Monzonite and less Quartz monzonite. The main texture in Dioritic rocks is intergranular and in Monzonite is Porphyritic. Based on TAS diagram Samples located in Diorite, granodiorite and gabbrodiorite. Tectono-magmatic diagram Y Versus Zr shows the magmatic arc setting and Zr/TiO2 Versus Ce/P2O5 diagram contrasts postcolligenal magmatic arcs. Based on Chondrite and primitive mantle Spider diagrams, LREE have enriched to HREE in this area that makes the overal slope of these diagrams declined from left to right and this consident with the overal pattern of subduction zone. The results of petrography, geochemistry and tectonic setting studies in this area, indicate that neogene magmatism occurred in post colligenal tectonic setting - subduction of Neo-thetise ocean under central Iranian plate in neogen era.
S. A. Majidi; M. Lotfi; M. H. Emami; N. Nezafati
Abstract
The metallogenic zone of Bafgh-Saghand in central Iran hosts huge low-titanium iron oxide-apatite (IOA) deposits (also called Kiruna type iron deposits) with more than 1500 Million tons grading 55% iron. The genesis of these deposits including Chadormalu, Choghart, She-Chahun, and Esfordi has long been ...
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The metallogenic zone of Bafgh-Saghand in central Iran hosts huge low-titanium iron oxide-apatite (IOA) deposits (also called Kiruna type iron deposits) with more than 1500 Million tons grading 55% iron. The genesis of these deposits including Chadormalu, Choghart, She-Chahun, and Esfordi has long been a subject of debate. In this regard, several hypotheses such as magmatic, hydrothermal, carbonatititc, BIF, and sedimentary-exhalative have been proposed so far. In this study, 20samples of the magnetite ore from the deposits of Chadormalu, Choghart, She-Chahun, and Esfordi were selected and analyzed for their oxygen isotope values. Based on the analyses results, the variations of δ18O values in the deposits are meaningful and result from the characteristics of the ore forming processes involved. The δ18O values of the analyzed magnetite samples range from -0.1 to +2.2‰ and indicate the role of both orthomagmatic (>0.9‰) and hydrothermal (<0.9‰) processes in the formation of these deposits. On the other hand, the values lower than +0.3‰ can be attributed to secondary oxidation or hydrothermal processes and/or a combination of both. The oxygen isotope data of the investigated samples are identical to the deposits such as El Laco of Chile, Kiruna and Grängesberg of Sweden, and Zhibo and Chagangnuoer of China with a magmatic-hydrothermal genesis. According to the geological and analytical evidence obtained from the iron oxide-apatite deposits of the Bafgh-Saghand area, first a tonalite-trondhjemite-granodiorite, diorite, and granite magmatism related to a continental margin subduction at 533 to 525Ma has caused a magmatic mineralization of iron in the area, while a later hydrothermal process related to an alkaline intrusion (syenite and monzosyentie) has caused a hydrothermal mineralization. Therefore a magmatic-hydrothermal source can be suggested for the formation of the low-titanium iron oxide-apatite deposits of the Bafgh-Saghand area.
S. A. Majidi; M. Lotfi; M. H. Emami; N. Nezafati
Abstract
The Origin of Iron Oxide-Apatite deposits (IOA) with low Ti or Kiruna type deposits has long been a matter of debate. In this case, several provenances have been proposed for these deposits which include: magmatic, magmatic-hydrothermal, hydrothermal, banded iron formations, and sedimentary-exhalative. ...
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The Origin of Iron Oxide-Apatite deposits (IOA) with low Ti or Kiruna type deposits has long been a matter of debate. In this case, several provenances have been proposed for these deposits which include: magmatic, magmatic-hydrothermal, hydrothermal, banded iron formations, and sedimentary-exhalative. Bafq-Saghand metallogenic zone is located in central Iran and hosts several large IOA type deposits including Chadormalu, Choghart, Se-Chahun, and Esfordi with nearly ~1500 mt ore with an average grade of 55%. Mineralization of REE-rich apatite is very common in these deposits, an issue that could be utilized for the study of their genesis. Fifteen apatite samples from the deposits of Chadormalu, Choghart, Se-Chahun, and Esfordi were taken and analyzed using LA ICP-MS. According to the geochemical analysis, the apatite of the abovemnetioned deposits show high enrichment of Y, Na, and Si, while very low content of Cl. Total REE content varies from 0.36-2.25% in which the LREE show an enrichment indicating strongly fractionation from HREE. Strong negative Eu anomaly (0.69-0.256) is observed. Sr and Y contents in apatites are 165-365 and 743-1410 ppm, respectively. The Fe-OH-Cl diagram shows that apatites is situated in the Hydroxil-fluoroapatite domain. The results show that these deposits are similar to those of IOA type deposits (e.g. Kiruna, El Laco, Abagong, Avnik, etc.). Apatite mineralization is unlikely related to carbonatitic magmatism, but situated in the Kiruna type and mafic rocks domain. The main mineralization event was likely related to tonalite-trondhjemite-granodiorite (TTG) and diorite-granite of arc magmatism (525-532 Ma) which were intruded into the Cambrian volcano sedimentary units (as country rock). Then the hydrothermal processes following alkaline intrusion (syenite and monzosyenite) led to mineralization. In general, the iron oxide-apatite (IOA) mineralization with low Ti has occurred through the magmatic-hydrothermal processes in the Bafgh-Saghand zone.
R Dabiri; M.H Emami; H Mollaei; M Ghaffari; M Vosougi Abedini; N Rashidnejad Omran
Abstract
Quaternary volcanic rocks are widely developed in NW of Ahar, NW Iran. Based on geochemical data, these rocks mainly consist of alkali basalts, trachybasalts, basaltic trachyandesites and trachyandesites. The major- and trace-element chemistry indicates that the lavas are dominantly alkaline in character. ...
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Quaternary volcanic rocks are widely developed in NW of Ahar, NW Iran. Based on geochemical data, these rocks mainly consist of alkali basalts, trachybasalts, basaltic trachyandesites and trachyandesites. The major- and trace-element chemistry indicates that the lavas are dominantly alkaline in character. The studied rocks display microlithic porphyritic texture with phenocrysts of olivine, clinopyroxene, and plagioclase ± amphibole ± biotite. Major and trace element abundances vary along continuous trends of increasing SiO2, Al2O3, K2O, Na2O, Ba and Rb decreasing CaO, Fe2O3* and Cr with decreasing MgO.The volcanic rocks in this area are characterized by the LILE and LREE enrichments and negative HFSE anomalies. The Sr and Nd isotopic ratios vary from 0.704463 to 0.704921and from 0.512649 to 0.512774, respectively.CaO/Al2O3 ratios versus MgO, La/Sm ratios versus Rb and Ba and Zr versus Th suggest that that fractional crystallization was a major process during the evolution of magmas. AFC modeling and isotopic data as well as microscopic evidence, clearly indicate that crustal contamination accompanied by the fractional crystallization played an important role in petrogenesis of the trachyandesites. Also, geochemical and isotopic compositions indicate that magma mixing was not essential process in the evolution of Ahar magmas. Alkali basaltswith high 143Nd/144Nd ratio, low 87Sr/86Sr ratio and high MgO, Ni and Cr contents indicate that they crystallized from relatively primitive magmas. REE modelling and Trace element ratios indicate that the alkali baslats were derived by small degrees (~1-3%) of partial melting from the spinel lherzolite.
M.H Emami; S Houshmand
Abstract
Mylonitic granite-granodiorites of Nowghan shear zone extend in NW-SE trend in the metamorphic rocks of the southwest Golpayegan. Different outcrops of mylonitic bodies have been studied in order to investigate the origin of granitoid rocks in Nowghan shear zone and determined their tectonic setting ...
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Mylonitic granite-granodiorites of Nowghan shear zone extend in NW-SE trend in the metamorphic rocks of the southwest Golpayegan. Different outcrops of mylonitic bodies have been studied in order to investigate the origin of granitoid rocks in Nowghan shear zone and determined their tectonic setting in Sanandaj-Sirjan zone. Field evidence, mineralogy and geochemical data suggest that the mylonitic rocks have S-type and strongly peraluminous characteristics. From the tectonic setting point of view, the granitoid bodies are of the collisional type and they formed as syn-tectonic to post-tectonic intrusions.
M. H. Emami; R. Monsef; N. Rashid Nejad Omran
Abstract
Miocene to Pliocene volcanic rocks in the Raveh region have exposed northern part of the Urumieh - Dokhtar Magmatic Belt. Neogene volcanic rocks are situated on Upper Red Formation. Magmatic activity separated in two phase. The first phase is composed of basic to intermediate volcanic rocks such as basaltic-andesite ...
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Miocene to Pliocene volcanic rocks in the Raveh region have exposed northern part of the Urumieh - Dokhtar Magmatic Belt. Neogene volcanic rocks are situated on Upper Red Formation. Magmatic activity separated in two phase. The first phase is composed of basic to intermediate volcanic rocks such as basaltic-andesite to andesitic lavas and pyroclastics (Ngv1).The second phase has intermediate to acidic rocks as well as andesite, quartz andesite and dacite (Ngv2).According to geochemical data, these samples show magmatic affinities to the calc-alkaline series. REE and trace element patterns show LREE enrichment relative to HREE, depletion in Nb, Ta and Ti, and also high Th/Yb and Th/Nb ratios relative to MORB and OIB. The parent magma of the Raveh volcanic rocks, with calc-alkaline compositions, has been originated probably from the metasomatized mantle with effective of fluids and sediment resulted from the Neothytian subducting slab. After collision between Arabian plate and Central Iran Block in Early Cenozoic, region experienced of crustal thickening and volcanism activity formed in relation to localized extensional basin in Early Miocene to Early Pliocene. The volcanism postdates continental collision, occurring in transtentional tectonic setting.
Gh. Tajbakhsh; M. H. Emami; H. Moine Vaziri; N. Rashidnejad Omran
Abstract
Nepheline syenite intrusive of Kaleybar is located in South and West of the Kaleybar city in eastern Azarbayjan province. This zoned intrusive complex is formed by penetration of two separated silica undersaturated and saturatated magmatic phases with Oligocene-Miocene ages. Undersaturated rocks are ...
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Nepheline syenite intrusive of Kaleybar is located in South and West of the Kaleybar city in eastern Azarbayjan province. This zoned intrusive complex is formed by penetration of two separated silica undersaturated and saturatated magmatic phases with Oligocene-Miocene ages. Undersaturated rocks are composed of alkali pyroxenite, mela alkali-gabbro to nepheline gabbro-diorte, nepheline syenite and nepheline sodalite syenite dikes. Silica saturated rocks is consist of a quartz monzonitic stock, which has penetrated in the center of nepheline syenite intrusive and related quartz syenite - micro syenite dikes. Undersaturated phase has potassic alkaline affinity and nepheline syenites are miaskitic Malignite. In contrast, silica saturated rocks belong to high-K calc-alkaline to shoshonitic magma. Field observation, petrographical and geochemical studies, indicates that undersaturated rocks are comagmatic and crystal fractionation, accumulation and low density minerals floatation processes play significant role in their magmatic evolution. High enrichment of rare elements especially LREE and LILE compare to variable depletion of HREE and HFSE are infer a basanitic parental magma generated from a previously subduction-metasomatised lithospheric mantle source. Silica saturated magma of Kaleybar was probably resulted form the lower crust Partial melting and geochemical similarities resulted from partial melting of lower crust and its geochemical similarities with undersaturated parts is due to magma mixing and contamination. Repeatedly injection of alkaline and calc-alkaline magmas could be occurred in a post collision setting after Eocene in Azerbaijan region.
M. Sabeti; M. H. Emami; A. Saeedi; K. Ajdary; A. Minaee; A. R. Nadimi
Abstract
Bouin– Miandasht Intrusive body is located in South- West of Golpayegan quadrangle and Sanandaj- Sirjan Zone. This Intrusion is composed of a compositional range including: porphyroid granite (monzogranite- syenogranite), granodiorite and gabbro – diorite. Variation diagrams of major and ...
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Bouin– Miandasht Intrusive body is located in South- West of Golpayegan quadrangle and Sanandaj- Sirjan Zone. This Intrusion is composed of a compositional range including: porphyroid granite (monzogranite- syenogranite), granodiorite and gabbro – diorite. Variation diagrams of major and trace elements show a trend of continuous compositive spectrum and affinity in granite to granodiorite and noncontinuous spectrum and lack of affinity between gobbro- diorite with the former group. All samples are metaluminous and slightly peraluminous, and rich in K contents. On the basis of geochemical data, these rocks are I- type granites characterized by depletion in Ta, Nb, P, Ti and enrichment in Cs, K, Sr, Rb, Ba that are obvious in the multi-element spider diagrams. The enrichment in LILEs and depletion in HFSEs reveal I- type metalominous volcanic arc granitoid (VAG).Satellite images and geological evidences show that there are 2 main fault systems in Golpayegan region with two trends of NW-SE and NE- SW.
A. Khakzad; A. Khakzad; H. Asadi; M. H. Emami
Abstract
Kahang exploration area located in Esfahan state and 10 Km of the east of Zefreh town that is located on Uromieh-Dokhtar volcanoplotonic belt. Primary results showed that it has good potential for resources of Copper (Cu) and Molybdenum (Mo). Kahang region is an alteration and breccia zone. Generally, ...
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Kahang exploration area located in Esfahan state and 10 Km of the east of Zefreh town that is located on Uromieh-Dokhtar volcanoplotonic belt. Primary results showed that it has good potential for resources of Copper (Cu) and Molybdenum (Mo). Kahang region is an alteration and breccia zone. Generally, more than %90 of rocks of this region has been affected by hydrothermal fluids.The occurrence of altration zones and Iron Oxides were confirmed by Satellite images processing. Faults and linear features were recognized using Satellite images (ETM) processing and PCA method. 320 litho geochemical samples of the area have been collected. They were chemically analyzed For geochemical survey . For the reason of irregular distribution of the elements in haloes related to porphyric massives , the normal data are used for study of distribution pattern of indicator elements and drawing maps . Also , the degree of correlation between elements are calculated using some statistic methods such as spearman and pearson and cluster analysis .Based on factor analysis method is distinguished that principal elements of the area are affected by 4 factors. In the next stage , geochemical maps of unielement of soil and rock samples are drawed for study of pattern of zonation of elements . Based on threshold limit method , the anomalous areas and pattern of zonation of elements are distinguished. Also, for separating and identifying the important anomalies, the P.N. method was used. For investigation of geochemical behaviors of Cu and Mo, anomalous maps of 10 elements were drawn which are Cu, Mo, Au, Ag, Pb, Zn, As, Sb, Mn and Ba. Consequently, it was found that in central part of Quartzmonzonites and Diorites areas the most concentration of Cu and Mo have been occurred, whereas in the margin of the andesitic rocks areas there is the most concentration of supergeous ores such as Pb, Zn and Ag.
To get better results and also to select the proper points for drilling, the composites haloes method was used and on the base of standard normalized data, the map of composite haloes of supergene and hypogen ores were drawn. The Solovof method was used for evaluation of erosion surface in ore area. The results show that the ore is located in subsurface and has not been destroyed by erosion.
I. Monsef; M. Rahgoshay; M. H. Emami
Abstract
The Late Jurassic to Early Cretaceous Orzuieh volcanic sequence is exposed in the southern part of the Sanandaj – Sirjan Zone. Major and trace element geochemistry shows magma evolution from the transitional to the calc-alkaline series. Clinopyroxene compositions are similar to their composition ...
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The Late Jurassic to Early Cretaceous Orzuieh volcanic sequence is exposed in the southern part of the Sanandaj – Sirjan Zone. Major and trace element geochemistry shows magma evolution from the transitional to the calc-alkaline series. Clinopyroxene compositions are similar to their composition in subduction setting and support a volcanic arc related environment. REE and trace element diagrams show enrichment patterns in LREE relative to HREE and depletion in Nb and Ta elements. This magmatic sequence has been originated from the mantle source with effect of liquids and sediment resulted from the subducting slab. The Orzuieh volcanic sequence is probably originated during the subduction of the Neo-Tethyan Oceanic lithosphere under the Sanandaj – Sirjan Zone, during the Late Jurassic to Early Cretaceous time, in the volcanic arc tectonic environment.
M. Aghazadeh; M. H. Emami; H. Moin Vaziri; N. Rashidnezhad Omran; A. Castro
Abstract
Khankandi pluton is located in northwestren part of Iran, within Garadagh (Arasbaran) - south Armenia block. Main units of the pluton are monzonite and granodiorite associated with minor gabbro and lamprophyric and dacitic dykes. Granodioritic plutonism is followed by gabbro and monzonite. Lamprophyric ...
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Khankandi pluton is located in northwestren part of Iran, within Garadagh (Arasbaran) - south Armenia block. Main units of the pluton are monzonite and granodiorite associated with minor gabbro and lamprophyric and dacitic dykes. Granodioritic plutonism is followed by gabbro and monzonite. Lamprophyric and dacitic dykes are emplaced at the end of the granodioritic plutonism. Gabbro and monzonites are shoshonitic, and granodiorites and dacites have high K-calc alkaline nature and charactistics of C-type (potassic or continental) adakites and high Ba-Sr granitoides. Lamprophyres are alkaline and have camptonitic composition. The monzonites follow fractionation trend of gabbro with minor crustal assimilation and contamination. Melting of garnet bearing mafic lower crust, metasomatised lithospheric mantle and upwelling asthenosphere produced granodioritic and dacitic, shoshonitic gabbro and lamprophyric magma respectively. The production of various magma types in the Oligocene of the Arasbaran occurred in response to slab break off and/or delamination of lithospheric mantle and upwelling of asthenosphere. Plutonism occurred after collision between Iranian and Arabian plates and crustal thickening in the extensional post collisional tectonic setting.
Z. Azimzadeh; M. H. Emami; R. Hajialioghli
Abstract
The Zand-Abad area is located in NW Ahar of north Azerbaijan. Magmatic rocks in this area consists of granitoids including monzogranite, granodiorite, monzonite and syenogranite as well as mafic rocks mainly diorite and associated extrusive rocks as andesite, trachyandesite, dacite, trachydacite, rhyolite. ...
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The Zand-Abad area is located in NW Ahar of north Azerbaijan. Magmatic rocks in this area consists of granitoids including monzogranite, granodiorite, monzonite and syenogranite as well as mafic rocks mainly diorite and associated extrusive rocks as andesite, trachyandesite, dacite, trachydacite, rhyolite. Subvolcanic rocks are porphyritic diorite and porphyritic monzodiorite. According to the different geochemical studies, the tectonic environment of Zand-Abad volcanic and plutonic rocks is determined as continental arc setting related to dilatory creep down subduction. This will be interpreted in relation with the Neotethyse post-collision activities. Considering the mineralogy and chemical evidence, we suggest that the Zand-Abad magmatic rock types (i.e. volcanic, sub-volcanic and plutonic rocks) have been derived from single magmatic source and undergone fractional crystallization, magma mixing and crustal contamination, resulting from hybrid granitoids. Magmatic series of the different types of magmatic rocks is alkaline. Calc-alkaline and shoshonite property of some samples is interpreted related to magma mixing and crustal contamination processes.
zahra badrzadeh; M. Sabzehei; E. Rastad; M. H. Emami; D. Gimeno
Abstract
The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons ...
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The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons in distal part of the deposit, the occurrence of a stringer zone discordantly under massive ore, the presence of pyrite as the main sulfide mineral, brecciated textures and mineralogical zonation in the massive ore, all suggest that the Sargaz deposit can be classified as a volanogenic massive sulfide deposit. The mineralogy is reasonably simple, with pyrite being the main sulfide mineral, with lesser chalcopyrite and sphalerite. On the basis of different generation of minerals, shape, size, their mutual geometry, relative timing of crosscutting structures and replacement features, brecciated textures and mineralogical zonation indicate that the growth history of the Sargaz deposit was complex due to syn and post depositional processes. Based on mineralogical, textural and paragenetic relationships, four principal stages of mineralization are recognized. Stage I mainly consist of fine grained pyrite (As rich), and locally sphalerite, quartz and barite. Framboidal pyrite, colloform pyrite and sphalerite were formed during this stage. After stage 1 mineralization, collapse of the sulfide mounds took place probably due to dissolution of anhydrite matrix, producing accumulations of pyrite breccias. Following this mound collapse, during stage II, pyrite (Co rich), sphalerite, tetrahedrite-tenantite and galena were formed as euhedral and coarse grains. Stage III deposits consist of chalcopyrite replacements and zone refining process. During this stage, due to zone refining, a chalcopyrite-pyrite zone was developed at the lower part of the massive sulfide lens and a sphalerite-rich zone formed in the upper part. During stage IV, over refining process, led to the dissolution of stage III chalcopyrite and base-metal depleted pyrite body in the lowermost part of the massive sulfide lens and carbonate veins were emplaced into the sulfide lens replacing earlier barite.
F. Gharib; Y. Lasemi; M. H. Emami
Abstract
The clastic facies of Kahar Formation were identified in the studied sections of coastal, deltaic and fluvial and also carbonate facies in shallow marine environments. The vertical displacements of Kahar Formation in these study sections show an overall major transgressive upward cycle. The petrography ...
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The clastic facies of Kahar Formation were identified in the studied sections of coastal, deltaic and fluvial and also carbonate facies in shallow marine environments. The vertical displacements of Kahar Formation in these study sections show an overall major transgressive upward cycle. The petrography of plutonic and semi- plutonic igneous rocks indicate that they consist mainly of monzogabbro- diorite and in some cases, alkaline syenite. According to the results of Kahar Formation's plutonic rocks petrography and studies of related facies, the basin of this formation was a continental rift.
N. Amel; M. Moayyed; A. Ameri; M. Vosoghi Abedini; M.H. Emami; M. Moazzen
Abstract
The Plio-Quaternary calc-alkaline magmatism in Azerbaijan, northwest Iran, occurs as stratovolcanoes, lava flows and domes consisting of andesitic basalts, andesites, dacites, rhyodacites, and pyroclastic materials. The volcanic rocks unconformably cover the Miocene sedimentary ...
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The Plio-Quaternary calc-alkaline magmatism in Azerbaijan, northwest Iran, occurs as stratovolcanoes, lava flows and domes consisting of andesitic basalts, andesites, dacites, rhyodacites, and pyroclastic materials. The volcanic rocks unconformably cover the Miocene sedimentary formations. The chemistry of the felsic-intermediate volcanic rocks indicates that the parent magmas are medium-K calc-alkaline and metaluminous in nature, and are distinguished by Na2O/K2O> 1. The volcanic rocks are enriched in LILE and LREE, and depleted in Y, Nb, and HREE, and display highly fractionated REE patterns, with no Eu anomaly. They display post-collision and continental margin arcs affinities. The post collision convergence between Arabia and Eurasia continental plates, starting in Miocene, resulted in significant shortening, thickening, and uplift of the crust in northwestern Iran and eastern Turkey, and shaped the present Iran-Turkey Plateau.
The thermal perturbation processes in the underlying asthenospheric mantle led to partial melting at a low degree, producing alkali- basalt magmas, with garnet remaining stable in the source region. The ascent of the basaltic magma and its emplacement in the lower crust resulted in the partial melting of the crustal materials and development of acidic magma. These processes led to the ascent and eruption of the felsic magmas prior to the mafic magmas. Mixing of mantle-derived mafic magmas with felsic magmas of crustal origin, produced hybrid magmas of intermediate composition. The occurrence of inverted volcanic sequences, where olivine-alkaline basalts are underlain by calc-alkaline felsic-intermediate rocks, are typical features of bimodal volcanic activities in the Plio-Quaternary times in Azerbaijan.
There are mineralogical as well as geochemical evidences that AFC-type processes were involved in the evolution of the Plio-Quaternary volcanic rocks in Azerbaijan. A comparison of geological and geochemical characteristics of the Plio-Quaternary volcanic rocks from northwest Iran with those from eastern Turkey indicates that the two areas share similar evolution paths in the petrogenesis of magmatic rocks.
Gh. A. Moafpourian; M. Pourmoafi; M. Vosoughi Abedini; M. H. Emami; M. R. Jannessari; S.w. Parman
Abstract
Scattered outcrops of ultramafic – mafic rocks and interbeded sedimentary layers in the North of Fariman – Torbat-e- Jam lineament are exposed mainly at the west of Mashhad, east of Fariman and north of Torbat-e- Jam in Agh- Darband area. Our studies on ultramafic – mafic rocks have ...
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Scattered outcrops of ultramafic – mafic rocks and interbeded sedimentary layers in the North of Fariman – Torbat-e- Jam lineament are exposed mainly at the west of Mashhad, east of Fariman and north of Torbat-e- Jam in Agh- Darband area. Our studies on ultramafic – mafic rocks have revealed several fields and petrographic evidences which demonstrate their volcanic to subvolcanic origin. Moreover, observation of various disequilibrium textures including the presence of glass, elongate and hopper pyroxene and olivine, occurring as pyroxene spinifex and olivine microspinifex textures in mafic and ultramafic rocks, can just be explained on the basis of their volcanic origin. On the basis of geochemical criteria, defined by IUGS for high MgO ultramafic and mafic volcanic rocks, these rocks are classified as komatiitic, picritic and basaltic types. Essential geochemical contrasts, including various ratios of incompatible immobile trace elements and different patterns of REE and spider diagrams, are too high to be explained on the basis of various degrees of partial melting of a uniform mantle source or AFC processes. It is thus possible to consider the role of a heterogeneous mantle source and/or dynamic melting in petrogenesis of these rocks. Furthermore to the cited heterogeneity which can be explained by mantle plume assumption, position of Fariman’s samples in the diagrams of (Nb/Th)N versus (Nb/La)N and Nb/Th versus Zr/Y which mainly plot at the OPB area, and Zr/Y versus Nb/Y which plot on or above ∆Nb line, coincide with the same assumption. Here we have argued that disequilibrium textures had been formed by undercooling of superheated melts, originated from an ascending mantle plume source, and rapid growth of crystals in such a melts. This arguement is favored with regard to high Fo contents of olivines which make necessary equilibrium of these crystals to high MgO contents and hot melts. We have estimated the MgO content and temperature of parent melt as much as 23.74% and 1470-1535ºC respectively based on maximum Fo content of olivine crystal in a komatiitic sample. These values are too high to correspond to a subduction or even a normal MORB related environments; however, similar to a hot spot tectonic setting.
A. Khakzad; A. Khakzad; H. Asadi; M.H. Emami; I. Rasa
Abstract
Regional exploration of Kahang is located at 73 km of north east of Esfahan city and 10 km of east of Zefreh town. This deposit is located in Uromieh-Dokhtar volcanoplotonic belt. For the first time this deposit was investigated with using the satellite images processing (TM). Base on the primary study, ...
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Regional exploration of Kahang is located at 73 km of north east of Esfahan city and 10 km of east of Zefreh town. This deposit is located in Uromieh-Dokhtar volcanoplotonic belt. For the first time this deposit was investigated with using the satellite images processing (TM). Base on the primary study, such as field survey, geophysical study, R.S.and petrography and mineralogy investigation the region was founded suitable place for resources of Copper (Cu) and Molybdenum (Mo). Kahang region is an alteration and breccia zone. In generally, more than %99 of rocks of this region are affected by hydrothermal fluids become in the low and high alteration degrees. The rocks of the area include Andesite, porphyritic andesite, Dacite, porphyritic rhyodasite, Diorite, Quartz monzonite and porphyry micro granite. In plutons, from rim to center of massive, is a trend from basic to acid features with less age. For geochemical surveying, 174 soil samples in systematic method and 143 rock samples of the area have been collected. They are been analyzed for 45 elements using ICP – MS method in Amdel laboratory of Australia. After assurance of accuracy of the results, statistic parameters are calculated. Then correlation coefficient measures of data calculation using two and multi variables analyze methods. Thus, based on mean measures and standard deviation of normalized data of elements, anomaly of locations is distinguished and they are presented as a table. At this stage for separation and identification of important anomalies using P.N. method. For introducing of the best locations for excavation and also study of geochemical behaviors of Cu and Mo, anomalous maps of 10 elements drown include of Cu, Mo, Au, Ag, Pb, Zn, As, Sb, Mn and Ba. The anomalous maps are drown in first step based on standard normalized duet and percent measures and in the second step with threshold limits plus amounts of standard deviation. Accordingly, it is delineate that the most concentration of hypogenous ores such as Cu and Mo in central part of area in Quartz monzonites and Diorites occurred, whereas the most concentration of supergeous ores such as Pb, Zn and Ag in the rim part of area in andesitic rocks occurred. Finally, for attainment of better results and recognition of anomalies correlated to ores, the composites haloes method is used and the map of composite haloes of supergene and hypogen ores are prepared based on standard normalized data. Solovov method is used for evaluation of erosion surface in ore area. On this base, if the amount of sum of standard normalized data of supergen ore to hypogens ratio is larger than one, we can conclude that the main ore bodies exist in the depth and it conserved from erosion processes.
R. Mohamadi; M.H., Emami; M. Vosoghiabedi
Abstract
The area is located about 230 km of southwest of Tehran. Based of geological observations, the plutonic rocks in the area consist of Neogene (Miocene) alkaline gabbro , gabbrodiorite, locogabbro and diabase . The Oligo - Miocene calc-alkaline extrusive rocks are dacite - ryodacite , andesite trachyandesite ...
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The area is located about 230 km of southwest of Tehran. Based of geological observations, the plutonic rocks in the area consist of Neogene (Miocene) alkaline gabbro , gabbrodiorite, locogabbro and diabase . The Oligo - Miocene calc-alkaline extrusive rocks are dacite - ryodacite , andesite trachyandesite , hornblendandesite , basaltic andesite and trachybasalt .Studing on isotopic analyses of Nd and Sr indicate that surveyed area were contaminated with crustal rocks of Sialic composition . In isotopy geochemical studies, The Andesite samples are plotted in the limit of BSE; however, it seems that mantling rocks besides being settled in crust (esp. the upper continental crust) have been contaminated with in. The combination of BSE towards enrichment, from the proportion of 87Sr/86Sr has shifted; a sample of rocks shows this position. Spider diagrams related to trace elements of plutonic samples which are used for identifying the tectonic setting show intrusives are in the extensive regime; while the lavas don’t have a steady trend and are similar to subduction zones. This shows that the intrusives of the the investigated area are different genesis from the southern volcanic rocks.
S. Malecootyan; Sh. Hagh-Nazar; M. Ghorbani; M. H Emami
Abstract
Petrological,geochemical and isotropic evidence of crustal contamination of the Quaternary basic rocks of Ghorveh-Takab axis is presented in this paper. These rocks are olivine basalt and basalt and they are plotted in the field of alkaline suites in geochemical diagrams.
Some ...
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Petrological,geochemical and isotropic evidence of crustal contamination of the Quaternary basic rocks of Ghorveh-Takab axis is presented in this paper. These rocks are olivine basalt and basalt and they are plotted in the field of alkaline suites in geochemical diagrams.
Some evidence, such as the presence of gneissic xenoliths, quartz xenocrysts with reaction rims and biotite phenoblasts in the basic rocks of the study area and high amount of potassium and high values of ratios, high concentration of LREE in comparison with HREE, high values of ratios and low values of ratios all indicate the crustal contamination of basic magma during its ascent.
J. Ahmadian; M . H. Emami; M. R . Ghorbani; M . Murata
Abstract
Kal-e Kafi granitoid complex is a part of Central Iranian structural zone called Yazd block. This complex is composed of a wide spectrum of plutonic rocks ranging from gabbro to alkalike granite with age range of Upper Eocene-Lower Oligocene. Potassic granitoid shows geochemical ...
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Kal-e Kafi granitoid complex is a part of Central Iranian structural zone called Yazd block. This complex is composed of a wide spectrum of plutonic rocks ranging from gabbro to alkalike granite with age range of Upper Eocene-Lower Oligocene. Potassic granitoid shows geochemical and mineralogical characteristics distinct from other plutonic rocks in the complex. The potassic granitoids are peralkaline and ferroan while other plutonic rocks in the complex are alkaline to calc-alkaline and magnesian. With respect to REE abundances and patterns, the potassic rocks of the complex are different from other Kal-e Kafi granitoids. Low REE abundances of the potassic granitoids indicate that the rocks could not be related to other plutonic bodies through magmatic differentiation. This would probably demonstrate that different petrogenetic processes were involved in petrogenesis of the potassic granitoids. The potassic granitoids are likely to be the consequence of crustal partial melting.