Economic geology and mineralogy studies of Chah Gabri copper deposit, south of Damghan

Chah-gabri copper deposit is located 90km south of Damghan at Semnan province, in the northeast part of Central Iran at a structural zone bottom of the Turud_Chah Shirin volcanic-sedimentary strip. This strip is eastern-western, in the form of a cross between two faults of Trood in the south and Anjilu in the north. Trend of all units are northwest – southeast) N65̊w (parallel to the zone. Copper mineralization in this area is vein-veinlets and open space fillings along the fracture and faults are composed of lava and tuff units. Minerals host rocks are mainly volcanic lava containers such as basalt andesite, andesite, trachy andesite and less sedimentary pyroclastic. The main minerals forming the deposit include sulfides (Chalcopyrite, pyrite, chalcocite and coveline), carbonate (malachite), iron oxides (hematite, goethite and limonite), and gangue minerals (Calcite, Quartz). Ore mineral textures include: vein-veinlets, open space filling, replacement and disseminated textures.

Study area is located in Semnan province, 90 km south of Damghan city, in geographical coordinates 54° 20´ to 54° 26´ northeast longitude and 35°17´ to 35 ° 23´ north latitude. During several stages of field visit, based on lithology and mineralogical diversity, 58 samples of rock and ore were taken with their geographical coordinates. Of these, 22 are thin sections, 14 are polished sections and 8 are thin - polished sections. Eventually they were prepared and studied. Overall, they were analyzed in the laboratories of Iran Minerals Research and Processing Center (IMIDRO) in which, 4 samples were studied by X-ray diffraction method (XRD), 7 by x-ray fluorescence (XRF) and 8 by ICP- MS method.

The results of geological, mineralogical, structural and textural studies of minerals show that much of the Copper mineralization is in the form of open space filling. Among the host rock components, units with a combination of andesite, basalt andesite and trachy andesite have been observed. Copper mineralization in this area is in the form of chalcopyrite, chalcocite, covolite and natural copper. It also occurs in the form of malachite on surface outcrops. In the study of fluid inclusion, temperature was175 to 200 degrees Celsius, salinity was 4 to 10.5 wt.% equivalent to NaCl and density was 0.9 to 1 g / cm3, which were determined to indicate the epithermal range.

Considering all field and laboratory evidence including host rock composition, texture and mineralization, zones alterations, major and associated metal elements, paragenetic sequence, the geochemistry and thermometry of fluid interconnects. Chahgabri copper deposit is in good compatibility with Manto type deposits, but due to vein ore mineralization, it can be classified as low sulfide vein epithermal hydrothermal deposits.