Economic Geology
Simindokht Younesi; Mohammadreza Hosseinzadeh; Mohsen Moayyed
Abstract
Mineralogy of oxide zone as clue about past climate reveals occurrence of supergene enrichment processes in Mahour Zn-Cu-(Pb-Bi-Ag) mineralization, in central Lut, during two stages: In first stage that supergene processes have occurred from meteoric waters in an arid climate during Oligocene to Upper ...
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Mineralogy of oxide zone as clue about past climate reveals occurrence of supergene enrichment processes in Mahour Zn-Cu-(Pb-Bi-Ag) mineralization, in central Lut, during two stages: In first stage that supergene processes have occurred from meteoric waters in an arid climate during Oligocene to Upper Miocene, leached capping contains jarosite, natrojarosite and goetite in various ratios and less hematite and sulfur has formed with supergene argillic alteration with quartz, alunite, kaolinite, montmorilonite, and gypsum. In response to neutrialization of solutions, an abundance of smithsonite and malachite with neotocite, greenokite /hawleite and minor azurite and silicate, phosphate and arsenate minerals precipitated in oxide zone and immature sulfide enrichment generated. In second stage, atachamite, paratacamite and chrysocolla have been formed through the interaction of saline waters and preexisting copper oxides after the onset of hyperaridity at Pliocene, and have been preserved since that time. Mineralogy features of leached capping provide insighs into hypogene ore mineral and alteration types and indicate sufficient acid has not been produced for effective leaching of Cu and hence, do not suggest extensive chalcocite enrichment under water table. An interpretation that mineralogy of oxide zone is also illustrative of it and results from exploration drill holes confirm it. With respect to style of Mahour polymetal mineralization and similar mineralizations in district, detail investigation of oxide zone and mapping leached caps in deposit and district scale can be used as suitable exploration tool in the search for conceal ore deposits..
Economic Geology
Mitra Eftekhari; Mohammad reza Hosseinzadeh; Mohsen Moayyed
Abstract
The Studied area is located in vicinity of the Sherbit village, about 28 km to the northwest of Ahar (in Eastern Azerbaijan province. Quartz monzonite intrusion is the host rock of hydrothermal tourmaline in this area. On the basis of their textural features, the tourmalines can be divided into four ...
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The Studied area is located in vicinity of the Sherbit village, about 28 km to the northwest of Ahar (in Eastern Azerbaijan province. Quartz monzonite intrusion is the host rock of hydrothermal tourmaline in this area. On the basis of their textural features, the tourmalines can be divided into four groups: 1) tourmaline veins, 2) tourmaline-breccias, 3) massive tourmaline and 4) pore space filling tourmaline. Based on the petrography and electron microprobe analysis studies, tourmalines of Sherbit area are correspond to intermediate schorl-dravite with more tendencies toward dravite composition and have been formed in hydrothermal conditions. According to reasons such as more Mg values compared to Fe, low Al amounts, fine scale zoning, content of fluorine, tendency toward outer side of alkali- and proton-deficient vectors and lack of negative correlation between Fe and Mg. Separated tourmaline from the quartz– tourmaline vein shows a very similar pattern to the quartz monzonite samples, which are characterised by a pattern with depletion in HREEs relative to LREEs. It can be concluded that REE concentrations and patterns of tourmaline from the different studied tourmaline rocks are controlled by the host rock and not by the hydrothermal fluid causing boron metasomatism.
M.R Hosseinzadeh; S Maghfouri; M Ghorbani; M Moayyed
Abstract
The study area is located in Arasbaran metallogenic zone. Rocks of the Sonajil region include Eocene andesite lava, porphyry microdiorite, Incheh granitoid and Ozuzdaghi Plioquaternary volcanic rocks. Porphyry microdiorite is the main host rock of porphyry type Cu- Mo mineralization in the Sonajil deposit. ...
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The study area is located in Arasbaran metallogenic zone. Rocks of the Sonajil region include Eocene andesite lava, porphyry microdiorite, Incheh granitoid and Ozuzdaghi Plioquaternary volcanic rocks. Porphyry microdiorite is the main host rock of porphyry type Cu- Mo mineralization in the Sonajil deposit. Much of the mineralization in the Sonajil deposit is dispersive and vein- veinlet type. Based on the structure, mineralogy and texture, the Sonajil vein- veinlets can be divided into sex different groups. These veins - veinlets contains sulfide (pyrite, chalcopyrite, molybdenite, bornite, galena, tetrahedrite, tenantite and enargite), hydroxide and oxide (magnetite and spicularite) and carbonate (malachite and azurite) minerals. Various types of fluid inclusions including mono-phase vapor, two-phase liquid and vapor, and multiphase liquid-vapor-solid of primary origin are present within quartz-sulfide veinlets.TH (L-V) for halite-bearing inclusions homogenizing by disappearance of halite and of vapor are 260-565˚C, 320-520˚C, respectively and salinity are 35.3- 69 % NaCl. TH (L-V) for two-phase inclusions homogenizing temperatures are 180-565˚C, and salinity are 0.7- 15.17 % NaCl. In bivariate plot of TH-salinity, two distinct populations of high and low salinity fluids are recognizable and most of the data points relating to the high salinity plot above the halite saturation curve. The coexistence of vapor-rich two-phase and halite-bearing inclusions having similar TH ranges can be indicative of boiling in the Sonajil porphyry deposit.
S. Younesi; M. R. Hosseinzadeh; M. Moayyed
Abstract
The Mahour Zn-Cu-(Pb-Bi-Ag) deposit located in central Lut Block, formed in an intensely crushed fault zone, dominantly in dacite-rhyodacite volcanic-subvolcanic unit of Late Eocene- Oligocene age. Mineralization occurred as veins, veinlets and breccia massive sulfide and/or as quartz , quartz-carbonate ...
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The Mahour Zn-Cu-(Pb-Bi-Ag) deposit located in central Lut Block, formed in an intensely crushed fault zone, dominantly in dacite-rhyodacite volcanic-subvolcanic unit of Late Eocene- Oligocene age. Mineralization occurred as veins, veinlets and breccia massive sulfide and/or as quartz , quartz-carbonate or quartz-muscovite (sericite)- carbonate vein-veinlets. Apart from negligible dark sphalerite, only fine-grained pyrite is observed as disseminated phase within the host rocks. Hypogene mineralization is complex and the main minerals, in order of abundance, are pyrite, Fe-bearing sphalerite and chalcopyrite, with subordinate galena, Cu-sulfosalts, Bi-sulfosalts, Fe-poor sphalerite, and afew greenokite, arsenopyrite, digenite and probably covellite. The Considerable amounts of Ag exist in lattice of some sulfosalt and sulfide minerals, as well as locally negligible Au-bearing W minerals. Mineralization is dominantly associated with sericitic, intermediate argillic and propyllitic alterations and rarely with advanced argillic and quartz- adularia that formed at three main stages including: 1- quartz- pyrite, 2- Fe- bearing sphalerite, and 3- chalcopyrite stage with sulfosalts and minor high sulfidation minerals. Mineralization occurred after silicification and disseminated pyritization that comprise tourmaline (sericitic alteration prior to mineralization) and then weathering process affected it. According to very low dissolution of Cu in Cu-Zn-S equilibrium system, high density of chalcopyrite inclusions in Fe-bearing dark sphalerites in Mahour reveals replacement origin of chalcopyrite disease texture. This texture and mineralogy (ore and alteration) indicate formation of Mahour polymetal mineralization at temperature range of 200-400°C and from an intermediate sulfidation state and low acidity fluid which was neutralized to alkaline by interaction with wall rock. Although, a minor evidence for evolution to high sulfidation state, more acidic and oxidation conditions is recorded in Cu- rich zone. Mineralogical features of the Mahour deposit indicate predominantly magmatic origin for mineralizing hydrothermal fluid, and in combination with mineralization structure, association with calc-alkaline to shoshonitic igneous rocks and tectonic setting of host rocks, are very similar to cordilleran style polymetal lode deposits.
Economic Geology
S. Maghfouri; M. R. Hosseinzadeh; A. Rajabi; A. M. Azimzadeh
Abstract
Darreh-Zanjir Zn-Pb deposit is located at the south of Taft city. Sulfide minerals in this deposit include sphalerite, galena and pyrite. Replacement, open space filling, vein-veinlet, breccia and massive are the typical textures in the Darreh-Zanjir deposit. Mineralization is associated with normal ...
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Darreh-Zanjir Zn-Pb deposit is located at the south of Taft city. Sulfide minerals in this deposit include sphalerite, galena and pyrite. Replacement, open space filling, vein-veinlet, breccia and massive are the typical textures in the Darreh-Zanjir deposit. Mineralization is associated with normal fault. Gange mineral is dolomite and dolomitization is related to mineralization. Three types of dolomite have been recognized in the Darreh-Zanjir region: 1- Regional dolomite, formed during diagenesis of micritic limestone of the Taft formations and is exposed in whole region. It has dark gray color and fine crystals. 2- Thrusting dolomite, formed during compression and thrusting of the Taft formation on the Darreh-Zanjir formation, this dolomites are located at the vicinity of thrust fault.3- Mineralization and dolomitization occur adjacent to normal fault. This dolomite is known as hydrothermal dolomite (DH) and it decreases away from of sulfide mineralization. Geochemical studies suggest that high content of cadmium in sphalerites represents low temperature for ore forming fluid. Supergene and oxidation process caused change of sulfide minerals to non-sulfide minerals. Non-sulfide minerals of the Darreh-Zanjir deposit are smithsonite, hemimorphite, hydrozincite, cerrusite and Fe-oxides and hydroxides. The most important characteristics of mineralization at the Darrh-Zanjir deposit such as tectonic setting, post compression of normal fault controlling mineralization, host rocks, mineralogy, metal content as well as wall textures, show similarities with Mississippi Valley-type (MVT) Zn-Pb deposits.
A Kamali; M Moayyed; N Amel; M.R Hosainzadeh
Abstract
Sungun Cu-Mo porphyry deposit is located in East Azarbaijan province and at northwest of Iran. From the petrology viewpoint, the Sungun copper mine is consisted of porphyry Sungun (SP), and eight categories of delayed dykes made of quartz-diorite (DK1 (a, b, c)), gabbro-diorite (DK2), diorite (DK3), ...
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Sungun Cu-Mo porphyry deposit is located in East Azarbaijan province and at northwest of Iran. From the petrology viewpoint, the Sungun copper mine is consisted of porphyry Sungun (SP), and eight categories of delayed dykes made of quartz-diorite (DK1 (a, b, c)), gabbro-diorite (DK2), diorite (DK3), dacite (DK4), lamprophyre (LAM) and micro-diorite (MDI). The main minerals of lamprophyric dyke are biotite, plagioclase, K-feldspar, and amphibole with porphyritic and microlithic porphyre textures. Lamprophyric dykes in the studied area have alkali-basalt composition and based on whole rock geochemistry is originated from a shoshonitic magma. Minerals chemistry analysis revealed that the composition of plagioclase varies from oligoclase to albite, amphibole is Magnesiohornblende and biotite composition varies from siderophyllite to eastonite. Lamprophyric dykes have been originated from a magma with high oxygen fugacity. Based on biotite thermometry, the temperature of biotite crystallization in lamprophyric dyke was 650 to 750°C. According to the mineralogical and geochemical evidence, studied lamprophyre samples are of kersantite type and belong to calk-alkaline lamprophyres. Multi-element diagrams normalized to chondrite and primitive mantle indicates LREE and LILE enrichment and HREE and HFSE depletion in the lamprophyre dykes Sungun. Based on trace elements ratio diagram of La/Sm vs. La parental magmas can have been generated from low degree partial melting of subcontinental mantle source with garnet-lherzolite composition. The dykes formed in Post-collisional geotectonic environment of the studied samples and trace element geochemical evidence indicate that produced magma formed from a metasomatic mantle due to an ancient subduction.
S Maghfouri; M.R Hosseinzadeh; R Rajabi; A.M Azimzadeh
Abstract
The early Cretaceous sedimentary sequence in south of Yazd hosts numerous Zn-Pb-Ba mineralization horizons. The sequence based on the stratigraphic position, age and composition of the rocks, can be divided into tree lower, middle and upper parts. The lower part or Sangestan formation mainly formed from ...
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The early Cretaceous sedimentary sequence in south of Yazd hosts numerous Zn-Pb-Ba mineralization horizons. The sequence based on the stratigraphic position, age and composition of the rocks, can be divided into tree lower, middle and upper parts. The lower part or Sangestan formation mainly formed from clastic sedimentary rocks such as conglomerate, sandstone, shale, siltstone and oolitic limestone. The thick Sangestan sedimentary sequence is well exposed resting unconformably on the Jurassic Shir-Kuh granite and metamorphic Shemshak Group. The middle part or the Taft formation include organic matter-rich shale, siltstone, limestone and dolomite. The upper part or the Abkuh (Darreh-Zanjir) formation comprised of shale, chert-bearing bedded limestone and marls, overlying concordantly on the Taft formation. The Zn-Pb-Ba mineralization horizons within the sedimentary sequence, based on stratigraphic position, relative age and type of host rocks involved the two horizons: the first horizon consisting of Mehdiabad, Farahabad and Mansourabad deposits, occurred in the lower part of the Taft formation and hosted by organic matter-rich shale, shaly limestone, siltstone, silty limestone and dolomite. The second horizon comprising Mehdiabad and Mansourabad deposits are hosted by black shale and chert-bearing bedded limestone locates within the middle part of the Abkuh formation.
S Younesi; M.R Hosseinzadeh; M Moayyed; A Maghsoudi
Abstract
The study area is located at the center of the Lut area and the southern part of the Eocene- Oligocene Lut volcano-plutonic belt. The main exposed igneous rocks include widespread and thick units of Middle Eocene volcanic (basaltic andesite, andesiteand trachy-andesite) and Eocene-Oligocene volcanic-subvolcanic ...
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The study area is located at the center of the Lut area and the southern part of the Eocene- Oligocene Lut volcano-plutonic belt. The main exposed igneous rocks include widespread and thick units of Middle Eocene volcanic (basaltic andesite, andesiteand trachy-andesite) and Eocene-Oligocene volcanic-subvolcanic (dacite and rhyodacite) with related tuffs, intruded by microdioritic stock and dykes of Oligocene with gabbrodiorite to quartzdiorite compositions. Texture is dominantly porphyritic and the main minerals are plagioclase, clinopyroxene, hornblende, K-feldspar, quartz and minor amounts of biotite with apatite, zircon, rutile and opaque minerals as accessory phases. These rocks with predominant K-high calc-alkaline to shoshonitic affinities, are I type and metaluminous and are characterized by LILE, LREE and Th enrichment relative to HFSE, depletion in Nb,Ti,Ta and weak depletion in HREE and Y. These features are characteristic of the post-collisional calc-alkaline rocks along with a continental active margin tectonic setting. In spite of the low ratios of Nb/U, Nb/La and Ce/Pb, the Sm/Yb (1.6-2.1) ratio reveals low contamination of magmas with relatively thin crust which is in accordance with low crustal thickness in this area (36-38Km). According to geochemistry of trace elements and REEs, the main cause of magmatism in Mahour was melting of a metasomatized lithospheric mantle (E-MORB like) with spinel lherzolite composition accompanied by very small amount of garnet in the presence of phlogopite. On the basis of the phenocrysts assemblage, REE pattern with negative Eu anomaly (Eu/Eu*= 0.63- 0.9) and also La/Yb calibration to crustal thickness, magmas have undergone relatively dry crystallization in the magma chamber at shallow depths (
M.R Hosseinzadeh; S Maghfouri; M Moayyed; A Rahmani
Abstract
The Khalifehlu Cu-Au deposit is located ~7 km North of Khoramdareh, in the central part of the Tarom magmatic zone. Rock units exposed in the area consist of volcanic, subvolcanic and intrusive rocks, which are associated with Eocene tectonics and Magmatism. Volcanism started with large-scale ...
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The Khalifehlu Cu-Au deposit is located ~7 km North of Khoramdareh, in the central part of the Tarom magmatic zone. Rock units exposed in the area consist of volcanic, subvolcanic and intrusive rocks, which are associated with Eocene tectonics and Magmatism. Volcanism started with large-scale andesitic-trachyandesitic lavas and pyroclastics; continued by rhyolite domes, and culminated by a quartzmonzonite porphyry. Copper-gold mineralization at the Khalifehlu is intimately associated with the breccias and veins. The highest grade and most extensive mineralization occurs in silicic veins. Two stages of mineralization are identified at the Khalifehlu area that progressed from regional breccia (phase 1 from stage 1) to Au- bearing silicic- sulfide vein- veinlet (phase 2 from stage 1) to oxide-dominant breccias (phase 1 from stage 2) to specularite vein- veinlet (phase 2 from stage 2). Gold occurs with sulfide minerals as disseminations, as well as in the veins and breccia cemented during phase 2 from stage 1. The wall–rock alteration in the Khalifehlu deposit exhibits a clear concentric zoning pattern. The vuggy quartz and argillic alteration are spatially and closely associated with high-grade gold mineralization, and are mainly developed along veins and in breccias. Propylitic alteration is widespread around the ore bodies. Pyrite, chalcopyrite, bornite, covollite, chalcocite, hematite and native gold are present in the ores. The ore minerals show disseminated, vein-veinlet, replacement, fibrous and breccia textures. We suggest near-surface emplacement of volatile-rich quartzmonzonite porphyry, followed by extensive brecciation and hydrothermal alteration-mineralization. The geology, alteration, and mineralization in the Khalifehlu deposit is similar to high-sulfidation type epithermal deposits.
M.R Hosseinzadeh; S Maghfouri; M Moayyed; M Lotfehnia; B Hajalilou
Abstract
The studied area is located in Tarom metallogenic zone (NW of Iran). This area illustrate widespread hydrothermal alteration and disseminated and vein-veinlet type copper, lead and zinc mineralization.Injection of qm Intrusive body into Eocene volcano clastic complex (Karaj Formation) along linear Faults ...
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The studied area is located in Tarom metallogenic zone (NW of Iran). This area illustrate widespread hydrothermal alteration and disseminated and vein-veinlet type copper, lead and zinc mineralization.Injection of qm Intrusive body into Eocene volcano clastic complex (Karaj Formation) along linear Faults caused intense hydrothermal alterations such as phyllic, argillic, propylitic and silicification. The major minerals of this rock are plagioclase, biotite, pyroxene, hornblende, alkali-feldespar, quartz with Lesser amount apatite, zircon, opaq minerals, rutile and sphene. Based on microscopic and geochemical assessments this rock is quartz- monzonite, tonalite, quartz- monzodiorite, and has calk-alkaline to shoshonitic and meta-aluminous character. This Pluton belongs to a volcanic arcs regime. The hydrothermal activities of penetrate intrusion causes the creation of two system vein and veinlet: ore bearing quartz vein- veinlet’s and non-ore bearing carbonate vein- veinlets. The mineralization in loubin- zardeh occured in quartz vein- veinlet along faults created via the intrusion of the intrusive. The main mineralizations of area are oxide (illmenite), sulfide (pyrite, Chalcopyrite, galena, sphalerite), sulfate (barite) and the supergene minerals are oxides and hydroxide, (hematite, goetite), sulfide (covelite), sulfate (anglesite) and carbonate (malachite and azourite). The most important characteristics of mineralization at the Lubin- Zardeh area such as tectonic setting, host rocks, mineralogy, metal content as well as wall rock alterations, and to compare these characteristics with the basic features of Epithermal deposits, the polymetal vein- veinlet mineralization in Lubin- Zardeh placed in the Epithermal category.
R Ferdowsi; A.A Calagari; M.R Hosseinzadeh; K Siahcheshm
Abstract
Astarghan area is located in ~ 50 km of north of Tabriz, southeast of Kharvana, East-Azarbaidjn. The area is a part of Gharadagh- Arasbaran metallogenic belt. The most important units in the area is a hypabyssal prophyritic to granular granodioritic intrusive body of Oligo-Miocene and flysch- type sedimentry ...
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Astarghan area is located in ~ 50 km of north of Tabriz, southeast of Kharvana, East-Azarbaidjn. The area is a part of Gharadagh- Arasbaran metallogenic belt. The most important units in the area is a hypabyssal prophyritic to granular granodioritic intrusive body of Oligo-Miocene and flysch- type sedimentry sequence of limestone, limy sandstone and marl (Paleocene-Eocene). Intrusion of the stock into the sedimentary rocks caused them to convert into a series of metasomatites and contact metamorphic rocks. Geostatistic studies on stream sediments and heavy mineral were done and include data processing, (i.e. normalization, univariate and multivariate analysis), and ultimately preparation of anomaly maps. The correlation coefficients among elements were determined. Elements that show positive correlations with gold are Cu, Hg, Pb, As, Sb, Ag, Bi and Mo. The results of preliminary regional geochemical explorations have led to discovery of two anomalous zones for gold; grade 1 and grade 2. The anomalies were verified by studies on heavy minerals in stream sediments and mineralized and altered samples taken from gold anomalous zones. The most important indentified heavy minerals include magnetite, malachite, gold, micaseous hematite, pyrite, galena, cerussite, pyrite- limonite, goethite, limonite, barite, hematite, pyrite- oxide which are affiliated with alteration and mineralzation zones. The major alterations in the area are argillic, sericitic and propylitic developed along the vein’s walls. Field and analytic studies done on samples taken from the gold anomalous zones led to identification of epithermal gold veins having over 4.5 ppm gold grade. The concordance of anomaly map with tectonic map and altered zones indicate that the faulted and fractured zones have played a crucial role in creation of gold anomalous zones. The incorporation of these data in the area led to introduction of several anomalous zones belonging to Au, Ag, Cu, As and Pb that can be used as passfinders for epithermal gold.
Gh Sohrabi; M.R Hosseinzadeh; A.A Calagari; B Hadjalilu
Abstract
The study area is located in north of East-Azarabaidjan (northwest of Iran). The most important intrusive bodies in the area include the Gharehdagh and Shivardagh batholiths and porphyry stocks of Sungun and Haftcheshmeh. The petrological and petrographical studies show that the composition of intrusives ...
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The study area is located in north of East-Azarabaidjan (northwest of Iran). The most important intrusive bodies in the area include the Gharehdagh and Shivardagh batholiths and porphyry stocks of Sungun and Haftcheshmeh. The petrological and petrographical studies show that the composition of intrusives varies from gabbro through diorite, monzonite, and granodiorite to granite. All bodies are I-type and mostly metaluminous and calc-alkaline with medium to high potassium belonging to volcanic arcs. The most important alterations in ore-bearing areas include silicic, potassic, propylitic, phyllic, and argillic. Mo mineralization occurred mostly in quartz veins and veinlets within the potassic zone in porphyry systems and veins and also in endoskarn associated with garnet skarns. The amount of Mo increases in differentiated and biotite-bearing acidic bodies that have high values of Si, K, Rb, and REEs. The intrusive bodies enriched with K, Rb, and Ba and depleted in Zr, Ta, Y, Yb, and Nb elements indicate metasomatism of the upper mantle by subducting oceanic crust and subsequent generation of magma and its passes through relatively thick crust. The bodies bearing Mo mineralization are located mainly in the center of batholiths and have quartz monzonitic and granodioritic compositions.
M.R Hosseinzadeh; M Moayyed; S Maghfouri; S Alipour; B Hajalilou
Abstract
The study area is located in Arasbaran Metallogenic Zone. The rocks of the Baloojeh region includes of Oligo-Miocene quartz-diorite porphyry, gabbro-diorite, quartz-monzonite and granodiorite. The quartz diorite is the main host rock of porphyry type Cu-Mo mineralization in the Baloojeh deposit, but ...
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The study area is located in Arasbaran Metallogenic Zone. The rocks of the Baloojeh region includes of Oligo-Miocene quartz-diorite porphyry, gabbro-diorite, quartz-monzonite and granodiorite. The quartz diorite is the main host rock of porphyry type Cu-Mo mineralization in the Baloojeh deposit, but also in the other intrusive porphyries, copper mineralization can be seen. Much of the mineralization in the Baloojeh deposit is dispersive and vein- veinlet type. Based on the structure, mineralogy and texture, the Baloojeh vein- veinlets can be divided into four different groups. These veins - veinlets contains sulfide (pyrite, molybdenite, chalcopyrite, boehrnite, galena, and sphalerite), hydroxide and oxide (magnetite, hematite and goethite) and carbonate (malachite and azurite) minerals. Similar to other Cu- Mo porphyry deposits, the Baloojeh deposit contains of potassic, phyllic, argillic and propylitic alterations. The parent magma of intrusives has calk-alkaline to shoshonitic character that implaced in a post-collisional magmatic arc. The fluid inclusion study has been done on the different groups of veinlets. These studies suggest high temperature (221- 381 C°) and high salinity (5- 45 % NaCl) hydrothermal fluid and the occurrence of boiling phenomena in the ore- forming hydrothermal fluids of the Bloojeh deposit.
M Ghorbani; M.R Hosseinzadeh
Abstract
The mafic-ultramafic complex of Misho is exposed in in the northwestern part of Iran, in the East Azerbaidjan province (southwest of Marand). This complex intruded in the older rock units including the Kahar formation and resulted in developing of contact metamorphic rocks. Compositionally, the mafic ...
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The mafic-ultramafic complex of Misho is exposed in in the northwestern part of Iran, in the East Azerbaidjan province (southwest of Marand). This complex intruded in the older rock units including the Kahar formation and resulted in developing of contact metamorphic rocks. Compositionally, the mafic portion is gabbronorite, troctolite and olivine-gabbronorite; and the ultramafics are harzburgite to lherzolite. The EPMA analyses of main minerals in mafic rocks (gabbro) show that plagioclases are anorthite to bytownite, Olivines are mainly chrysolite, orthopyroxenes have enstatitic composition, clinopyroxenes are diopsidic and amphiboles are tschermakite, to tschermakitic hornblende. Geothermobarometery of gabbros based on varions methods (Al2O3 and TiO2 in amphibole, plagioclase - amphibole and orthopyroxene – clinopyroxene) yield 700- 900ºC in pressure of 7-8 kbar.
