M Nejadhadad; B Taghipour; A.R Zarasvandi; A.R Karimzadeh Somarin; S Salamab Elahi
Abstract
Located 20 km north of the Delijan city, the Pb-Ba-Ag ore deposit was mineralized in the lower Cretaceous carbonate host rocks in the Ravanj anticline. Geographically, the Ravanj anticline is part of the Urumieh-Dokhtar magmatic arc in the Zagros orogenic belt. Deposition of the ore took place in the ...
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Located 20 km north of the Delijan city, the Pb-Ba-Ag ore deposit was mineralized in the lower Cretaceous carbonate host rocks in the Ravanj anticline. Geographically, the Ravanj anticline is part of the Urumieh-Dokhtar magmatic arc in the Zagros orogenic belt. Deposition of the ore took place in the lower part of massive limestones where they have been structurally thrusted over the shale and shale-limestone strata. Breccia filling, host rock replacement and disseminated ore are the main textural features of mineralization. Mineralization consists of fine-grained galena, barite, variable amounts of pyrite, and minor amounts of sphalerite, tetrahedrite, and chalcopyrite. Despite extensive pyritization, marcasite was not found in the ore, indicating that the ores were mineralized from a fluid having a pH > 5. Fluid inclusion microthermometric studies were done in the calcites of pre-main-stage mineralization (C2), in main-stage barite and in post-mineralization calcite (C3). Average homogenization temperatures of fluid inclusions are approximately equal: 165 ˚C in the pre- main stage calcite, 160 ˚C in post-mineralization calcite and 175 ˚C in barite, but their salinities change from lower than 1 to higher than 18wt% NaCl equivalent. Silica precipitation in the Ravanj deposit is very limited, in agreement with minor changes in temperature of fluid during mineralization. The wide range in salinity of the fluid inclusions plus contemporaneous deposition of barite and fine-grained galena are evidences for mixing of two geochemically different fluids. One of them was probably a low-salinity (5.6 wt% NaCl), CO2-beaing and sulfur-rich fluid. At a temperature of 160 ˚C, the neutral pH is about 5.8. Therefore the sulfides were deposited from fluids having a pH of 5-6. The effect of low-salinity, CO2-beaing fluid is to buffer the system. The second fluid, which was probably oxidized, saline (15.7 wt% NaCl) and metal-rich, shows salinity and homogenization temperatures characteristic of MVT ore forming fluids.
M Farhadian Babadi; F Masoudi; A.R Zarasvandi
Abstract
Considerable quantities of wastes are generated in drilling operation contain various components such as heavy metals and hydrocarbons. These wastes are discharged in pits or the sea, which their geochemical composition should be investigated for waste management. In this study, sampling of heavy water ...
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Considerable quantities of wastes are generated in drilling operation contain various components such as heavy metals and hydrocarbons. These wastes are discharged in pits or the sea, which their geochemical composition should be investigated for waste management. In this study, sampling of heavy water based mud additives; different lithology of the Gachsaran formation and soils around location was performed. After preparation, metal concentrations in samples were determined by ICP-MS method. The results showed that the concentration of metals such as lead, copper, arsenic, zinc, molybdenum, antimony, mercury, and strontium in the Gachsaran wastes are more than standards and soils of the region. In addition, the calculated correlation coefficients between elements in wastes showed that possible mineral phases as impurities associated with barite. The environmental assessments also suggested that these wastes are extremely polluted for Ag, Sb, As, Cu, Pb. Using pure barite could reduce the amounts of the heavy metals.
N Zaheri; A.R Zzarasvandi; M Karevani; M Karevani; H Pourkaseb; F Rastmanesh
Abstract
The Aligudarz region is located in middle part of the Sanandaj-Sirjan Zone. During and before the Jurassic time, a variety of Cu, Fe, Zn-Pb and Ba mineralization are formed in this area due to tectono-magmatic activities. This diversity of mineralizations with volcano-plutonic activities caused some ...
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The Aligudarz region is located in middle part of the Sanandaj-Sirjan Zone. During and before the Jurassic time, a variety of Cu, Fe, Zn-Pb and Ba mineralization are formed in this area due to tectono-magmatic activities. This diversity of mineralizations with volcano-plutonic activities caused some complexities and ambiguities in geology-metallogeny evolution of the region. In this way, the aim of this study was investigation of geological evolution and its relation with mineralization and tectono-magmatic evolution of the Aligudarz region. The field and petrographic observations show that mineralization composition consist of barite with sulfide minerals (chalcopyrite, pyrite and covellite) and Fe-oxides in the Farsesh deposit withPermian carbonate host rock in the Farsesh area; sphalerite, galena and chalcopyrite in the Jurassic phylite, slate and meta-sandstone host rocks (Gol-e Zard deposit) and Cu mineralization associated with andesite rocks. In order to approach these aims, sampling for petrographical and geochemical studies with ICP-MS was done from each ore body separately. In addition, the granitoid rocks of the region were considered. In the Gol-e Zard Zn-Pb deposit, REE pattern represent enrichment of LREEs and La/Lu>1. The metamorphic host-rocks show positive Ce and negative Eu anomalies, whereas sphalerite, galena, chalcopyrite and quartz show negative Eu and Ce anomalies. Lack of Eu anomalies indicates high Oxygen fugacity during the precipitation of these minerals. Therefore, according to similarity of REE pattern in host-rock and ores of the Gol-e Zard deposit, it seems REEs extracted from host rock and then added to mineralizing fluid. The chondrite normalized pattern of REEs in barite ores and its host rocks in the Farsesh deposit show LREE enrichment. The positive Eu and negative Ce anomalies indicate that hydrothermal fluids are the main fluids, which caused precipitation of barite inthe host rock. REE pattern of andesite rocks show the same magmatic source for these rocks. LREE enrichment in andesite samples, lack of Eu and Ce anomalies indicate that clinopyroxene and plagioclase were crystallized in the same time and Ce+3 extracted with other REEs from depositional environment. The chondrite normalized pattern of granite rocks in the region show LREE enrichment, negative Eu anomaly and lack of Ce anomaly, which can indicate that diffraction process was controlled by plagioclase crystallization during the granitoid generation. The chondrite normalized spider diagram show the same trend of depletion of HFSE and HRRE and enrichment of LREE and LILE for all of the samples, which represent occurrence of magmatism in the study area and indicate all of these mineralizations are related to the subduction zone. These studies indicate that there is geodynamically a genetic relation between mineralizing fluids and volcano-plutonic activities of the region during or before the Jurassic system.
