بررسي نحوه كاني سازي و تشكيل كانسار رگه اي مس-طلا گلوجه (شمال زنجان) بر اساس شواهد كاني شناسي، ژئوشيمي و سيالات درگير

Genesis of Golujeh Cu-Ag Vein Mineralization (N. Zanjan): Mineralogy, Geochemistry and Fluid Inclusion Evidences

Golujeh Cu-Au deposit is located in 45 km north of Zanjan city. Structurally it is part of Tarom-Hashtjin polymetal province in Alborz-Azarbaijan Zone of Iran. Based on 1:100000 quadrangle map of Hashtjin, the oldest exposure belong to Carboniferous limestone followed by Jurassic siltstone and shale, Cretaceous recrystalized low metamorphosed (Laramid orogenic phase) limestone. The igneous rocks are mainly volcanic and subvolcanic rocks of Eocene-Oligocene age, composed of tuff, ignimbrite, rhyolite, trachy-andesite, porphyritic andesite and rhyodacite. Major alteration assemblage is propylitic, argillic, sericitic and silicic alteration formed next to mineralized veins. The mineralization occurred along four major veins with average 2.5ppm Au, 0.6-1.5% Cu, l0ppm Ag, 2-3% lead and 1-2% Zn in hypogene and supergene suites. Hypogene minerals include magnetite, specular hematite, chalcopyrite, bornite, galena and sphalerite in association with cerusite, chalcocite, malachite-azurite, dijenite covelite and hemimorphite as supergene minerals. Gangue minerals are quartz, calcite and fluorite. Open space filling, brecciated and vuggy texture are the major mineralization textures in Golujeh deposit. Fluid inclusion studies reveals presence of ore fluids in range of 180-320°C, with two distinct mineralized fluids in range of 180-250°C for Au-Ag and 260-320°C for Cu-Pb-Zn mineralization. Au grade is 5ppm in some veins, associate with quartz, though no native gold were recognized in our study. Geochemical analyses indicate the positive correlation coefficent between Cu-Au (0.75), Pb-Au (0.84), Zn-Au (0.80) and Ag-Au (0.62) in mineralized veins. Considering field, mineralogic, geochemical and fluid inclusion evidences, Golujeh is a mesothermal to epithermal vein-type ore deposit.