| چکیده انگلیسی مقاله |
The Aregijeh and Emarat deposits are hosted by clastic-carbonate sequences of the Early Cretaceous in southern Arak. These deposits formed in the northern Sanandaj-Sirjan zone within an intracontinental rift tectonic setting. The main stratabound Pb-Zn mineralization horizon occurs in the upper part of thick-bedded Orbitolina-bearing limestones (Aptian-Albian), underlying shales and marls with intercalated thin-bedded limestones. Mineralization appears as banded, brecciated, laminated, disseminated, and veinlets, comprising primary sphalerite, galena, pyrite, galena, chalcopyrite, and sulfosalts, accompanied by quartz, dolomite, calcite, and siderite as gangue minerals. Silicification and carbonatization represent the dominant alteration types. The unusual abundance of fine-grained quartz, anhedral dolomite, and framboidal pyrite provides evidence of early diagenetic stages, while mineralization was completed by the precipitation of coarse-grained quartz, euhedral dolomite, siderite, and hydrothermal sulfides. Ore formation occurred in a submarine anoxic environment shortly after sedimentation. Microthermometric analyses of fluid inclusions in dolomite, quartz, and sphalerite reveal similar homogenization temperature ranges (125–207°C in Aregijeh vs. 131–217°C in Emarat) in both deposits. However, calculated salinities (7.59–13.72 wt.% NaCl equiv. in Aregijeh vs. 7.59–19.84 wt.% NaCl equiv. in Emarat) are higher in the Emarat deposit. Textural relationships, mineral assemblages, and fluid inclusion data suggest mineralization formed from basinal brines during diagenesis in a reduced environment, consistent with Irish-type deposits.
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