M.A.A Mokhtari; H Moinvaziri2; M.R Ghorbani; M Mehrpartou
Abstract
Au-Cu-Mo mineralization of Aniq-Qarachilar area is located in Arasbaran ore zone within the Qaradagh batholith. Mineralization in this area mainly includes Au-Cu-Mo bearing quartz veins within the granodiorite that cropped out in three areas include: Qarachilar (2 major veins), Zarlidareh (8 veins) and ...
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Au-Cu-Mo mineralization of Aniq-Qarachilar area is located in Arasbaran ore zone within the Qaradagh batholith. Mineralization in this area mainly includes Au-Cu-Mo bearing quartz veins within the granodiorite that cropped out in three areas include: Qarachilar (2 major veins), Zarlidareh (8 veins) and Qaradareh (some narrow and short veins). Alterations around the quartz veins include sericitic and silisification that has limited development. Quartz veins have compact, boxwork and brecciated texture. Sheeted veins of quartz present in some areas especially in the Qarachilar area. Sulfide mineral content of these veins commonly less than 10 percent and includes pyrite, As- bearing pyrite, chalcopyrite, molybdenite, bornite, stibnite, sphalerite and galena. Secondary minerals include coveline, malachite, azurite and iron hydroxides. Geochemical studies and grades of elements indicate that Au, Ag, Cu and Mo have high content in quartz veins. The average grade for Au in two quartz veins in the Qarachilar area is 5.76 and 3.9 ppm. The average grade for Au in the quartz veins in the Zarlidareh area is 4.7, 3.12, 2.6, 0.45, 1.09, 1.34, 1.15 and 0.58 ppm. The highest Au grade is about 359 ppm that belongs to a quartz vein with boxwork texture in the Zarlidareh area (ZV1). Moreover, W and Bi have high concentration in some veins. There is a good correlation between Au and Ag, Mo, W and Bi. Au grades in the Qaradareh quartz veins is low, but Mo grades vary between 0.15- 1.15%. Mineralization as silisic sheeted veins within the granodioritic intrusion, low concentration of sulfide minerals within the quartz veins, limited alteration aureole, Au mineralization together with Mo mineralization and high concentrations of Bi and W and relatively good correlation of Au with Ag, Bi, W and Mo indicate that Au mineralization in the Aniq-Qarachilar area can be classified as an intrusion related gold systems.
A. Maghsoudi; M. Yazdi; M. Mehrpartou; M. Vosooghi Abedini
Abstract
The Mirkuh Ali Mirza gold mineralization is located in north Sarab in the Western Alborz–Azerbaijan structural zone. Mineralization was formed in the form of a vein occurring in Neogene dacitic and rhyodacitic tuff along a series of NW–SE trending fault; Mineralization associated with quartz-sericite-adularia-calcite ...
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The Mirkuh Ali Mirza gold mineralization is located in north Sarab in the Western Alborz–Azerbaijan structural zone. Mineralization was formed in the form of a vein occurring in Neogene dacitic and rhyodacitic tuff along a series of NW–SE trending fault; Mineralization associated with quartz-sericite-adularia-calcite and pyrite(<1%) assemblages is a typical of low-sulfidation epithermal gold mineralization. The fluid inclusion data from quartz minerals indicate homogenization temperature of 161-260°C and salinities of 0.5 to 6.5 wt% NaCl equiv. The variation in gold grade in quartz vein is 270-3240 ppb. The highest gold content is in lattice and breccias quartz that can indicate direct relationship between boiling to gold deposition. The idea is supported by coexistence of vapor-dominant and liquid-dominant fluid inclusions.
M. A. A. Mokhtari; H. Moinvaziri; M. R. Ghorbani; M. Mehrpartou; G. Hosseinzadeh
Abstract
Kamtal skarn zone is located in the 20km north of Kharvana in the Eastern Azarbaijan. Skarn-type metasomatic alteration is the result of Kamtal monzonitic intrusion into the Upper Cretaceous impure carbonates. Kamtal skarn include exoskarn and endoskarn zones. Exoskarn is the major zone that its thickness ...
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Kamtal skarn zone is located in the 20km north of Kharvana in the Eastern Azarbaijan. Skarn-type metasomatic alteration is the result of Kamtal monzonitic intrusion into the Upper Cretaceous impure carbonates. Kamtal skarn include exoskarn and endoskarn zones. Exoskarn is the major zone that its thickness varies between 100-600m. Field and mineralogical studies demonstrate that exoskarn zone composed of garnet rich sub-zone (garnet skarn), epidote rich sub-zone (epidote skarn) and marble sub-zone. Garnet is the most important calc- silicate mineral within the garnet skarn sub-zone. They are mainly grossularitic in composition (Ad33-35), but along the fractures, andraditic composition (Ad66-73) is predominant. Clinopyroxene is the other dominant mineral within garnet skarn sub-zone that has diopsidic composition (Di82.8-85.7). In the epidote skarn sub-zone, epidote is the predominant mineral while garnet and clinopyroxene present in some places and have low concentration. Petrographic studies indicate that marly limestone was the primary rocks of the garnet skarn sub-zone while clay-bearing marl was the primary rocks of the epidote skarn sub-zone. Skarnification process can be categorized into two discrete stages: 1) prograde and 2) retrograde stages. Prograde stage began immediately after the initial emplacement of the Kamtal monzonitic magma into the enclosing impure carbonate rocks. The effect of heat flow from the intrusion caused the enclosing rocks to become isochemically marmorized in almost homogeneous limestone layers and bimetasomatized (skarnoid–hornfels) in thin interlayers of clay-rich carbonates. Invasion of segregated fluid phase of Kamtal intrusion into the fractures and micro-fractures of the marmorized and skarnoid–hornfelsic rocks incorporate considerable amounts of Fe, Si and Mg into the metasomatic aureole. During retrograde stage, due to relatively low temperature hydrothermal fluids and processes such as hydrolysis, carbonation and sulfidation, considerable amounts of hydrous calc-silicates, sulfides, oxides and carbonates replaced the anhydrous calc-silicates. Garnet and clinopyroxene are the most abundant mineral assemblage in Kamtal skarn zone, which were formed in temperature lower than 550°C. Lack of wollastonite in this mineral assemblage, intergrowth of garnet and clinopyroxene crystals and lack of any reaction rim between these crystals, and lack of emplacement texture indicate that they formed contemporaneously within the temperature and ƒO2 ranges of 430–550ºC and 10-26–10-23, respectively.
A. Maghsoudi; M. Yazdi; M. Mehrpartou; M. Vosoghi Abedini
Abstract
The Mirkuh Ali Mirza area is situated at north of Sarab, NW of Iran. The study area is located in in Meshkin Shahr 1:100000 geological sheets at western Alborz–Azerbaijan structural zone. The major exposed rocks in the area are the Eocene and Neogene volcanic and subvolcanic rocks which include ...
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The Mirkuh Ali Mirza area is situated at north of Sarab, NW of Iran. The study area is located in in Meshkin Shahr 1:100000 geological sheets at western Alborz–Azerbaijan structural zone. The major exposed rocks in the area are the Eocene and Neogene volcanic and subvolcanic rocks which include rhyolitic and dacitic tuff with intermediate to basic rocks. Recent geochemical stream sediment (1:25000 scale) and litogeochemical surveys showed base and precious metals in the form of veins at the periphery of a porphyry copper deposit model. Occurrence of this mineralization can be a small part of a big hydrothermal fluids circulation that its effects were developed in large scale up to 10km2 to porphyry copper mineralization. The mineralization model follow as; porphyry copper in center, gold and other base metals in periphery, anomalous concentration of Ag, As, Sb, Pb and Zn in more distal relative to central body and Mn, Ba and Hg can be found at the outer part of the system
M .A. Mokhtari; H. Moein Vaziri; M.R. Ghorbani; M. Mehr Parto
Abstract
Kamtal intrusion is located in East Azarbaijan province, NW of Iran, near the Armenia border. The Kamtal intrusion consist of an acidic part with monzogranitic composition and an intermediate- basic part which compositionally composed of monzonite, monzodiorite, quartz monzonite, quartz monzodiorite ...
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Kamtal intrusion is located in East Azarbaijan province, NW of Iran, near the Armenia border. The Kamtal intrusion consist of an acidic part with monzogranitic composition and an intermediate- basic part which compositionally composed of monzonite, monzodiorite, quartz monzonite, quartz monzodiorite and gabbro. Gabbroic rocks exist in the form of small lenses in the southeast of Kamtal intrusion within the intermediate part. The intermediate- basic part has been intruded by the acidic part. Both acidic and intermediate parts are high-K calc-alkaline, metaluminous in character and classified as I-type granitoids; while, the gabbros have tholeiitic nature.
Both acidic and intermediate rocks show a LREE rich pattern and high LREE/HREE ratio. These two parts have differences in MREE enrichment. From similarity in REE patterns of acidic and intermediate rocks a genetic relation can be discerned. Negative anomalies of Nb and Ti can be seen in all rock phases of the Kamtal intrusion, representing the subduction zone setting. Comparison of trace element variations with those of granitoid rocks of different tectonic settings show similarities between Kamtal intrusion and Andean volcanic arc granitoids. Furthermore, Kamtal intrusion can be classified as VAG based upon tectonic setting discrimination diagrams. It is concluded that, Kamtal intrusion probably is the result of Neotethys oceanic crust subduction beneath the Caucasus continental plate.
S. Ebrahimi; Y. Pan; S. Alirezaei; M. Mehrpartou
Abstract
The Sharafabad auriferous epithermal vein system is located in the Alborz-Azarbaijan magmatic assemblage in northwestern Iran. The veins are hosted by Eocene andesitic volcanic and pyroclastic rocks and tuffs. Wall rock alteration includes an inner silicic zone often bordered by argillic and propylitic ...
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The Sharafabad auriferous epithermal vein system is located in the Alborz-Azarbaijan magmatic assemblage in northwestern Iran. The veins are hosted by Eocene andesitic volcanic and pyroclastic rocks and tuffs. Wall rock alteration includes an inner silicic zone often bordered by argillic and propylitic zones. Mineralization is mainly restricted to silica and silica-carbonate veins and veinlets in faults and fault zones. A total of 18 ore-bearing veins have been identified. The veins vary from 10 -1000 meters in length and 0.5-10 meters in width, respectively. Pyrite is the main sulfide, commonly associated with subordinate chalcopyrite, sphalerite, and galena. Gold occurs as scattered microscopic grains in quartz and pyrite, and along the grain boundaries of the sphalerite, galena and chalcopyrite. Silica occurs as gray quartz, white quartz, clear quartz, opal, chalcedony, and minor amethyst. On the basis of crosscutting relationships and mineral paragenesis, four stages can be distinguished: (I) pre-mineralization, (II) mineralization, (III) post-mineralization and (IV) supergene. The gold and the base metals sulfides occurred in the mineralization stage. Fluid inclusion data have been obtained from the ore-stage gray quartz and sphalerite, carbonates, and the late clear quartz and amethyst. The fluid inclusions from the gray quartz indicate homogenization temperatures of 170-270 ºC and salinities of 1 to 8.7 wt% NaCl equiv. The fluid inclusions in the sphalerite indicated homogenization temperatures of 215-265 ºC, and salinities of 10.8-15.3 wt% NaCl equiv. The carbonates formed at lower temperatures, between 160-250 ºC, from fluids of low salinities, at 1.5-3.8 wt% NaCl equiv. Amethyst from final stages of vein formation, not associated with sulfides and gold was deposited at 173-203 ºC from fluids containing 3.5 to 9.5 wt% NaCl equiv. The coexistence of vapor-dominant and liquid-dominant inclusions in quartz and sphalerite suggests that boiling occurred during the evolution of the ore fluids. The occurrence of boiling is supported by hydrothermal breccias, bladed calcite, and adularia. Fluid inclusion data suggest that ore was deposited at an average depth of about 400 m below the paleosurface. Considering the intermediate argillic alteration, association of gold with base metal sulfides, and the moderate salinities, the Sharafabad district can be classified as an intermediate-sulfidation epithermal system.
A. Akbarpour; A. Rasa; M. Mehrpartou
Abstract
The Masjeddaghi area is a part of Alborz-Azarbaijan Zone and located in the Jolfa 1:100000 geological map sheet. The oldest rock units cropped out widely in the south and northeast of the area belong to the Eocene flysch-type sediments. The other outcrops consist mainly of volcanic rock complex of andesites ...
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The Masjeddaghi area is a part of Alborz-Azarbaijan Zone and located in the Jolfa 1:100000 geological map sheet. The oldest rock units cropped out widely in the south and northeast of the area belong to the Eocene flysch-type sediments. The other outcrops consist mainly of volcanic rock complex of andesites and trachyandesites affected by quartz monzonite intrusion and caused alteration of phyllic and carbonate phyllic type. The mineralization in volcanic complex is also accompanied by quartz and barite veins. The study of alterated zone around veins shows sericite, silicified, prophillitic, chloritic and alunite (jarosite) alterations. Investigation of alteration zones around mineralized veins shows epithermal gold ore in which alunitic alteration (jarocite) is the most important characteristics. The result of the study on alteration and extension of altered zones in the whole study area give rise to the probability of porphyry type copper deposit (potassic, phyllic, argillic and prophylitic alteration zone).
