QE389 : Mineralogy, geochemistry and genesis of the Abgareh copper deposit, south of Damghan
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2018
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Abstarct: Abgareh copper deposit located in Semnan province, 140 km southwest of shahrood and part of a Torud-Chah shirin volcanic-sedimentary belt that has facies in the northern edge Structural-sedimentary zones of Central Iran. Extensive and numerous alteration and mineralization were formed by volcanic and magmatic activity in this zone from Eocene to Miocene and are mainly related to the subduction events in this zone. The calc-alkaline volcanism and related mineralization occurred along the main Anjillo fault in the north and the Torud fault in the south with NW-SE trend. Field and petrographical studies, deposit area, consist of andesite, basaltic andesite and basalt and contains less includes crystal tuff that indicate middle–upper Eocene with argillitic, sericitic, silicic, carbonatic, chloritic and iron oxides alterations. The rocks are high-K, calc-alkaline to shoshonitic in nature. Mineralization in Abgareh area occurred as veins along the fault planes in a lava unit. Fractures resulting from operation of faults in the rocks of the region have created a favorable location for the influence of hydrothermal solution and it is considered as the main controller of mineralization. According to the field observations and mineralogical studies, the mineralization in the region was carried out in two stages: hypogene and supergene and weathering. Hypogen zone minerals are generally pyrite, chalcopyrite and bornite. Because of existence in oxidizing-supergene environment, nearly almost Cu-bearing minerals of the main stage of mineralization have been replaced by secondary Cu minerals such as chalcocite, covellite, malachite and chrysocolla. Fractures resulting from operation of faults in the rocks of the region have created a favorable location for the influence of hydrothermal solution and it is considered as the main controller of mineralization.The most textures observed in the occurrence of mineralization include vein-veinlets, open space filling, radial, replacement and disseminated. According to the geochemical data, the volcanic rocks have significant enrichment in LREE and LILE and depletion in HREE and HFSE and negative anomalies in Ti and Nb elements. The rocks are enriched in Cs indicating mantle mextasomatism by fluids released from subducting oceanic lithosphere. Therefore, magma contamination and mantle mextasomatism have affected the magma from which the volcanic rocks of the Abgareh have were generated. In variation diagrams there is a continuous trend between the mentioned rocks and indicate that they evolved by fractional crystallization. According to geochemical studies copper with Ag, As, Sb, Sn and W is a significant correlation. This correlation geochemistry is corresponded with mineralography evidence (mineral paragenesis sequence). Fluid inclusion data shows in the temperature range from 145 to 217 °C and salinity between 3.73 and 9.84 Wt %NaCl and depths less than 390 m. Most of the studied fluid inclusions are from liquid rich two phases (L+V) type. On the baxse of a forementioned evidences, the principle deposition mechanism of ore minerals was mixing of two meteoric and magmatic fluids. finally, regarding our research the petrography, struactural control of mineralization, alteration type and its extention, simple mineralogy, geochemical, fluid inclusion properties of the study area and comparison with similar epithelial deposits indicate that the Abgareh vein system is formed in a low-sulfidation epitermal environment.
Keywords:
#Mineralogy #Geochemistry #Cu (Ag) #low-sulfidation epitermal #Middle–Upper Eocene #Abgareh #Torud-Chah shirin Link
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
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