Fariba Asiay Soufiani; Hossein Kouhestani; Amir Morteza Azimzadeh
Abstract
Qarachilar Cu-Mo-Au mineralization is located within the Qaradagh batholite in the Arasbaran metalogenic zone. This area is a part of southern margin of Lesser Caucasus. Qaradagh batholite at the Qarachilar mineralization area composed of granodiorite- quartz monzodiorite (as the main phase and host ...
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Qarachilar Cu-Mo-Au mineralization is located within the Qaradagh batholite in the Arasbaran metalogenic zone. This area is a part of southern margin of Lesser Caucasus. Qaradagh batholite at the Qarachilar mineralization area composed of granodiorite- quartz monzodiorite (as the main phase and host rock of mineralization), diorite, quartz monzonitic stocks, apophyses of porphyritic granite and acidic to intermediate dykes. These intrusions have Upper Eocene- lower Miocene age. All of the mentioned intrusion phases have calc-alkaline to high-K calc-alkaline nature and classified as metaluminous I-type granites. The porphyritic granite apophyses and dykes, and quartz monzonitic stocks have adakitic nature and can be classified as high silica adakites. Chondrite normalized REE patterns in granodiorites- quartz monzodiorites indicate enrichment in LREE and flat trend in MREE and HREE, while porphyritic granites show steep pattern with enrichment in LREE and depletion in HREE. Based on field investigation, geological, petrological, geochemical and tectonomagmatic discrimination diagrams, it can be conclude that granodiorite- quartz monzodiorite phase was formed in active continental margin as a result of Neo-Tethyan ocean subduction beneath the Eurasia. The quartz monzonite stocks and porphyritic granites were formed in a post collisional setting from metasomatized lithospheric mantle wedge.
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.
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.
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.
