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Hossein Kouhestani

لیلا طالبی، میر علی اصغر مختاری، محمد ابراهیمی، حسین کوهستانی
رخداد معدنی آرپاچای، شمال تکاب: کانه زایی اپی ترمال فلزات پایه در پهنه فلززایی تکاب- انگوران- تخت سلیمان
The Arpachay mineral occurrence, north of Takab: An epithermal base metal mineralization in the Takab-Angouran-Takht-e-Soleyman metallogenic zone
Abstract


Arpachay Pb-Zn-Cu mineral occurrence lies in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, 60 km north of Takab. Rock units exposed in the area consist of Oligo-Miocene volcanic, volcano-sedimentary and sedimentary units which are intruded by gabbroic and granodioritic plutons. In this area, mineralization occurs as ore-bearing quartz veins hosted by gabbroic pluton. The gabbro shows hetero-granoular texture consisting of plagioclase and clinopyroxene phynocrysts. Geochemical data indicate a calc-alkaline affinity for the gabbroic rocks, associated with active continental margin. These data demonstrate contamination of parental magma with crustal materials. Based on microscopic studies, ore minerals are include galena, sphalerite, chalcopyrite with minor pyrite, and quartz and calcite are present as gangue minerals at the Arpachy occurrence. The ore minerals show vein-veinlets, disseminated, breccia, open space filling, boxwork, plumose, cockade and replacement textures. Hydrothermal alteration is restricted to the silicified, sericitic-argillitic and carbonatic altered parts of the ore zones. In the outer parts of the mineralization zones, alteration occurs as sericitization and calcitization-chloritization (propylitic alteration) of host gabbro. Four stages of mineralization can be distinguished at the Arpachy occurrence. These stages are progressed from brecciation and silicification of host rocks (stage 1) to quartz-chalcopyrite-pyrite‒cemented veins and breccias (stage 2), quartz-galena-sphalerite veins and veinlets (stage 4) and finally individual or sets of late barren quartz-carbonate veins and veinlets (stage 4). REE pattern of the host rocks and the mineralized samples indicate that mineralized samples are depleted in REE. This signature may indicates high W/R interaction at Arpachay. Geological, mineralogical and textural characteristics of Arpachay occurrence are comparable with intermediate-sulfidation style of epithermal base metal deposits.

 

 

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