پتانسيل سنجي كانه زايي مس-طلا و تعيين ژنز كانسار آهن سرويان دليجان، شرق استان مركزي

Determianation of Cu-Au Mineralization Potential an‎d genesis of Sarvian Iron Deposit, Delijan, Eastern Markazi Province

زمين شناسي

The Sarvian iron deposit, situated 28 km northeast of Delijan within the Urumieh–Dokhtar magmatic zone, comprises a suite of intrusive igneous rocks dominated by diorite, monzodiorite, granodiorite, an‎d tonalite. The emplacement of these bodies into Jurassic, Cretaceous, an‎d Eocene to Oligo–Miocene volcano–sedimentary units has resulted in intense contact metamorphism an‎d the development of calcic an‎d magnesian skarn zones. These skarn bodies occur as narrow ban‎ds along the contacts between the intrusions an‎d limestone, shale, an‎d siltstone, clearly displaying features of pervasive contact metamorphism an‎d alteration. Field surveys, petrographic analyses, an‎d mineralogical examinations indicate that the iron mineralization is of skarn type an‎d is accompanied by notable amounts of copper an‎d gold. The mineralization is characterized by three principal stages: 1. Prograde skarn stage: Formation of calcium silicate minerals (garnet, diopside, pyroxene) an‎d deposition of magnetite as a result of infiltration of high temperature magmatic fluids along the contact zone. 2.Retrograde skarn stage: Replacement of primary minerals by hydrous an‎d oxide minerals such as hematite an‎d specularite under the influence of cooler fluids an‎d groundwater. 3.Supergene stage: Dissolution an‎d re precipitation of minerals an‎d formation of secondary minerals such as goethite, malachite, an‎d chalcocite, accompanied by colloform, ban‎ded, an‎d cavity filling textures. The principal ore minerals include magnetite an‎d hematite, accompanied by accessory minerals such as pyrite, chalcopyrite, goethite, specularite, an‎d malachite. Observed ore textures comprise skeletal magnetite, martitization of magnetite, replacement textures due to supergene alteration, spheroidal textures, an‎d fracture–breccia structures resulting from tectonic movements. The dominant alteration types in the area are propylitic, carbonate, pervasive silicification, an‎d hematite alteration. The endoskarn zone is characterized by garnet, diopside, epidote, an‎d actinolite as key minerals. Geochemical analyses reveal significant enrichment in Fe, Cu, an‎d Au. Rare earth element (REE) distribution patterns indicate that the magmas belong to the calc alkaline, meta aluminous series associated with subduction related environments. They exhibit LREE enrichment, HREE depletion, a positive Pb anomaly, an‎d negative Ti, Nd, an‎d Zr anomalies, consistent with a crustal source an‎d magmatic processes contemporaneous with collisional events. Fluid inclusion studies show homogenization temperatures in the range of 110 to 179 °C (average 140 °C) an‎d average salinity of 22 wt.% NaCl equivalent, with two dominant ranges of 19–21 an‎d 22–25 wt.%. Most inclusions are two phase (liquid + vapor), an‎d their sulfide composition represents complexes that acted as the main carriers of metallogenic elements. Thermodynamic an‎d geochemical evidence confirm the role of mixing between these magmatic fluids an‎d low salinity meteoric waters in the mineralization process. Combined geological, geochemical, an‎d fluid inclusion data identify the Miocene quartz diorite intrusion as the primary driver of skarn formation an‎d Fe–Cu–Au mineralization in the Sarvian deposit, classifying it among iron skarn deposits with potential for copper–gold exploration.

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