پديد آورندگان :
فردوست, فرج‌الله دانشگاه صنعتي شاهرود - دانشكده علوم زمين - گروه زمين‌شناسي اقتصادي , اصغري, فاطمه دانشگاه صنعتي شاهرود - دانشكده علوم زمين - گروه زمين‌شناسي اقتصادي
كليدواژه :
چاه گبري دامغان , دگرساني و مس رگه اي , ميانبار سيال , زمين‌شناسي اقتصادي و كاني‌شناسي
چكيده فارسي :
كانسار مس چاه گبري در 90 كيلومتري جنوب شهرستان دامغان، استان سمنان، بخش شمالي پهنه ايران مركزي، بر روي نوار آتشفشاني-رسوبي، ترود-چاه شيرين واقع شده است. سنگ هاي ميزبان كانه زايي شامل: گدازه هاي زيردريايي با تركيب آندزيت، آندزيت- بازالتي و مجموعه آذرآواري از جمله توف، كريستال ليتيك توف، توف برش دگرسان شده و آگلومرا به سن ائوسن مياني مي باشند. براساس داده هاي ژئوشيميايي اين سنگ ها داراي ماهيت كالك آلكالن غني از پتاسيم تا شوشونيتي هستند. دگرساني هاي گرمابي شامل: آرژيليك، سيليسي و كربناتي، و هماتيتي شدن به همراه اكسيد و هيدروكسيدهاي آهن است. كانه زايي به صورت رگه اي و پركننده فضاي خالي در سنگ هاي ميزبان رخ داده است. براساس مطالعات كانه نگاري كاني هاي اصلي مس شامل كالكوسيت، كالكوپيريت، كووليت، مالاكيت و به ندرت مس طبيعي است كه با هماتيت، گوتيت و ليمونيت همراهي مي شوند. از ميان اين كاني ها، كالكوسيت و مالاكيت بيشترين فراواني را دارند. در مطالعه سيال درگير، دما 175 تا 200 درجه سانتيگراد، شوري 4 تا 10/5 درصد وزني معادل نمك طعام و چگالي 0/9 تا 1 گرم بر سانتي متر مكعب تعيين گرديد كه محدوده اپي ترمال را نشان مي دهد. عامل اصلي كانه زايي، چرخه گرمابي در امتداد ساختارهاي گسلي، شستشوي مس از سنگ هاي مسير و ته نشيني در فضاهاي خالي سنگ ميزبان بوده است.
چكيده لاتين :
IntroductionChah-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.Materials and MethodsStudy 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.Results and Discussion 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.ConclusionConsidering 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.
