Economic Geology
Shahram Mobaser; Taher Farhadinejad; Abbas Asgari; Mohammad Ali Ali Abadi; Shirin Fatahi
Abstract
The Barzavand copper deposit with Oligocene age located in 30 Km northeast of Zefreh along a tension fault with W-E trend and developed within basaltic lava with stratabound form. Alterations mainly include: pyritization, propylitization, zeolitization, silicification, saussuritization and uralitization ...
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The Barzavand copper deposit with Oligocene age located in 30 Km northeast of Zefreh along a tension fault with W-E trend and developed within basaltic lava with stratabound form. Alterations mainly include: pyritization, propylitization, zeolitization, silicification, saussuritization and uralitization of basaltic lava. Furthermore geochemical studies in Barzavand show enrichment of SiO2, Al2O3, K2O, Na2O, P2O5, TiO2, ∑REE, Ag, As, Ba, Be, Bi, Cd, Cs, Cu, Li, Mo, Nb, Pb, Rb, Sb, Se, Sn, Sr, Ta, Tl, Te, Th, U, W, Y, Zn and Zr, enrichment- depletion of CaO, Fe2O3, MnO, Hf, Sc and V and depletion of S, Ni, Cr, MgO and Co during alteration. The positive correlation between (La/Lu)N, (La/Yb)N, (La/Sm)N and (La/Y)N and CaO (r= 0.70 to 0.96) indicate propylitization of host rock basalt and increase in pH of fluid responsible for mineralization that play important role in differentiation of lanthanides in study area. Ore minerals include chalcopyrite, bornite, covellite, azurite, malachite, hematite, goethite and pyrite. Copper is transported by means of chloride complexes into oxidized brines water related to late diagenesis stage and precipitated by substitution within pyrites formed during the volcanism process. It seems that the Barzavand copper deposit has submarine volcanism, early and late diagenesis, burial metamorphism and weathering stages during its evolution. According to alteration properties, mineralogy and the whole rock geochemistry, the Barzavand copper deposit is most similar to Manto type copper deposits.
Economic Geology
shirin fatahi; Ahmad Jahangiri; Farhad Maleckqasemi; seyedhasan tabatabaei
Abstract
Abstract Qezelbalaq Arsenic ore deposite is located in Hashtrud, 120 km from southeast of Tabriz. In this district effect of dacitic Sahand domes on sandy limestones and Qom formation sandstone with Oligomiocene age and pyroclacitic units with Miocene age leads to formation of various types of alteration ...
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Abstract Qezelbalaq Arsenic ore deposite is located in Hashtrud, 120 km from southeast of Tabriz. In this district effect of dacitic Sahand domes on sandy limestones and Qom formation sandstone with Oligomiocene age and pyroclacitic units with Miocene age leads to formation of various types of alteration such as Silicic, phyllic, intermediate argillic, advanced argillic and dolomitization. It seems that Arsenic mineralization has occurred in two main step: 1) Pyrite± Chalcopyrite± Arsenopyrite that are consistent with phyllic zone. Fluide responsible mineralization have high temperature (nearly 250 centigrade degree) and fs2 between 10-15 to 10-20 and 2) Pyrite± Native arsenic± Realgar± Orpiment± Galena± Stibnite wich are consist with intermediate argillic and advanced argillic zones. Hydrothermal fluid in this stage has lower temperature (nearly between 180 to 210 centigrade degree) with fs2 between 10-7.8 to 10-13. These assemblage are associated with hematite, diaspore, kaolinite, alunite and arsenolite. Average of arsenic grade in phylilc zone is 655 ppm and in argillic zone is 11930 ppm. Mass change calculation indicate enrichment in many metals such as As, Sb, Hg, Ag and Au. According to geochemical studies, As, Hg and Sb are pathfinder for probebly Porphyry copper mineralization and gold in study area.
Sh Fatahi; A.A Calagari; A Abedini
Abstract
Neyestanak bentonite deposit is located in northwest of Naeen, Isfehan province. This deposit is an alteration product of Oligocene tuff breccias. Mineralogical considerations of this deposit show that montmorillonite, kaolinite, and quartz are the principal minerals which are accompanied by lesser amounts ...
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Neyestanak bentonite deposit is located in northwest of Naeen, Isfehan province. This deposit is an alteration product of Oligocene tuff breccias. Mineralogical considerations of this deposit show that montmorillonite, kaolinite, and quartz are the principal minerals which are accompanied by lesser amounts of anorthite, calcite, chlorite, illite, albite, dolomite, microcline, orthoclase, sanidine, and halite. Mineral chemistry investigations testify to the similarity of this deposit with Wyoming-type bentonite deposits. Geochemical studies reveal that bentonitization of tuff breccias at Neyestanak is accompanied by depletion of Ba, Co, Zn, Y, Ni, Sr, Au, Ca, Fe, Mg, Mn, P, Ti, and Na, enrichment of Si, Th, As, Hf, Nb, and U, and leaching-fixation of K, Pb, Cs, Rb, Zr, and Cu. Geochemical analyses make clear that variation of Eu and Ce anomalies in this deposit were controlled by the degree of alteration of feldspars and oxidation potential of the environment, respectively. By considering the results obtained from this study, it seems that factors such as differences in degree of alteration intensity of parent materials, physico-chemical conditions of the environment, adsorption, incorporation in crystal structure, access to complexing ligands, and differences in degree of resistance of the primary minerals against alteration played prominent role in mobilization, distribution, and concentration of elements in this deposit.
Sh Fatahi; A.A Calagari; A Abedini; H Bagheri
Abstract
Chahreeseh bentonite deposit is located at ~55 km northeast of Isfahan, structural zone of Central Iran. This deposit has layered and massive form and includes six discrete outcrops. The field observations showed that the ores are genetically related to Oligo-Miocene tuff breccia. The mineralogical studies ...
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Chahreeseh bentonite deposit is located at ~55 km northeast of Isfahan, structural zone of Central Iran. This deposit has layered and massive form and includes six discrete outcrops. The field observations showed that the ores are genetically related to Oligo-Miocene tuff breccia. The mineralogical studies testified to the presence of minerals such as montmorillonite, saponite, beidellite, cristobalite, anorthite, calcite, dolomite, albite, vermiculite, actinolite, pyrophyllite, quartz, sanidine nontronite, orthoclase, microcline, tridymite, and hematite in rock-forming quantities in the bentonitic samples. Based on the minerals chemistry considerations, the Chahreeseh bentonite deposit can be classified as the Wyoming type. The results of mass change calculations (with assumption of Hf as low-mobile index element) show that progression of bentonitization process at Chahreeseh was accompanied by depletion of elements like Al, Fe, K, Ti, Mn, P, Ba, Co, Zn, Cs, Rb, Y, Zr, Ni, Sr, and Cu, enrichment of U, and leaching-fixation of elements such as Na, Mg, Ca, and Si. The geochemical interpretations revealed that variations of Eu negative anomaly (0.27-0.90) and weak negative to weak positive anomalies of Ce (0.97-1.22) at Chahreeseh have been controlled by the degree of feldspar alteration and changes in the rate of oxidation potential of the environment, respectively. By considering the results obtained from field relations, mineralogy and geochemistry, it seems factors such as physico-chemical conditions of alteration environment, absorption mechanism, difference in degree of alteration intensity of parent materials, the degree of access to fluoride, chloride, and sulfate ligands, incorporation in crystal structure, ionic exchange, physical concentration, and the presence in resistant mineral phases played significant roles in distribution and concentration of elements in this deposit, respectively.
