S Hassanpour; S. Alirezaei
Abstract
The Masjeddgaghi Cu-Au deposit is located to the southeast of the Arasbaran zone, NW Iran, to the south of the Lesser Caucasus. Mineralization in Masjeddaghi is associated with an Eocene dioritic subvolcanic pluton intruded into older volcanic and sedimentary rocks. The Masjeddaghi intrusive body is ...
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The Masjeddgaghi Cu-Au deposit is located to the southeast of the Arasbaran zone, NW Iran, to the south of the Lesser Caucasus. Mineralization in Masjeddaghi is associated with an Eocene dioritic subvolcanic pluton intruded into older volcanic and sedimentary rocks. The Masjeddaghi intrusive body is high-K, calc alkaline, and meta-aluminous, and formed in an island arc subduction/collision setting. Hydrothermal alteration is distinguished by a potassic core marked by secondary biotite and K-spar that grades outward into a chlorite-rich propylitic halo. The ore minerals include chalcopyrite, associated with minor chalcocite, bornite, tetrahedrite, and trace molybdenite. Pyrite and magnetite are common associates. The Masjeddaghi deposit is elliptical in plan view, 500 x 400 m in diameters, and mineralization has been traced for several hundred meters from surface exposures. 40Ar/39Ar geochronology on secondary biotite from potassic alteration zone indicates that mineralization, and by corollary, the emplacement and crystallization of the Masjeddaghi porphyritic intrusion, occurred in 54.07 ± 0.53 Ma. The Masjeddaghi ore deposit shows geology, mineralization and alteration characteristics comparable to those typical of island arc type porphyry Cu-Au systems. Masjeddaghi ore deposit shows geology, mineralization and alteration characteristics similar to island arc porphyry type systems.
A Ghahramani Zakaria; H Nazari; M Pourkermani
Abstract
This research has been achieved with the purpose of morphotectonic studies of the Sufian-Shabestar fault zone in the West Alborz-Azerbaijan (NW Iran). The fault zone cuts the Neogene and Quaternary units in south of the MishoMountains. The maximum of horizontal and vertical displacements along the Sufian-Shabestar ...
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This research has been achieved with the purpose of morphotectonic studies of the Sufian-Shabestar fault zone in the West Alborz-Azerbaijan (NW Iran). The fault zone cuts the Neogene and Quaternary units in south of the MishoMountains. The maximum of horizontal and vertical displacements along the Sufian-Shabestar fault zone are H=2500±200 m in Meshnaq river and V=66±4 m in fan east of Benis village, respectively. The minimum of horizontal and vertical displacements along this fault are H=9±0/5 m in offset stream of N Sharafkhaneh city and V=6±4 m in river NW of Kozehkanan city, respectively, all estimated based on combining data of Digital Elevation Model in scale of 1/25000, aerial photographs in scale of 1/20000, LANDSAT ETM satellite imagery and field studies. The estimated rate of horizontal and vertical displacements are H=135±20 m V=19±4 m in NW of Sharafkhaneh city, respectively and all allow us to estimate the rake of fault by geometry calculations. Based on estimate, the rake of the Shabestar fault segment is 11±4W. The Sufian-Shabestar fault zone is a right lateral-reverse strike slip fault with strike N81E and rake range of between 04, 11 with westwards dip, all estimated based on the rake of fault plane and morphotectonic data. Therefore, the Sufian-Shabestar fault zone (including faults segments of Sufian, Shabestar, F1, Sharafkhaneh (F2) and F3) is neotectonically an active zone.
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.
