Economic Geology
Mohammad Boomeri; Somayeh Naruyi; Mohammadreza Ghodsi
Abstract
The Chah Sorbi area is located in the Sistan suture zone. The geology in the Chah Sorbi, from old to young, are flysch type rocks, Zahedan granitoid, subvolcanic granodiorite porphyry, dioritic to granodioritic dikes and recent deposits. The Pb mineralization in the study area occurs as thin and short ...
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The Chah Sorbi area is located in the Sistan suture zone. The geology in the Chah Sorbi, from old to young, are flysch type rocks, Zahedan granitoid, subvolcanic granodiorite porphyry, dioritic to granodioritic dikes and recent deposits. The Pb mineralization in the study area occurs as thin and short galena-bearing veins associated with pyrite, quartz, calcite, goethite and limonite. The host rocks are flysch and the subvolcanics that are undergone phyllic and argillic alteration. Propylitic alteration occurs in most dikes in the area and is characterized by chlorite, calcite and epidote. In northeast part of the area, the subvolcanic rocks were intruded by quartz stockworks and was strongly altered. The most intensive and extensive alteration with these rocks is phyllic alteration that is characterized by pyrite, quartz and sericite. Cu mineralization in the stock is characterized by presence of Cu-carbonate and –sulfides. Galena-bearing veins are probably epithermal type in the Chah Sorbi area that is situated in margin of a porphyry Cu system. Major and minor elements were measured in 7 least altered samples from intrusive rocks. The igneous rocks in the study area are metaluminous that are formed from a calc-alkaline magma in a continental margin volcanic arc setting.
Economic Geology
shahriar keshtgar; Sasan Bagheri; shahriar keshtgar
Abstract
Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, ...
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Abstract The Mahirud volcano-plutonic Complex (MVPC), known as Cheshmeh Ostad Group, an rock assemblage including several plutons and volcano-sedimentary successions, crops out at the northeastern part of the Sistan Suture Zone. Igneous rocks of the MVPC, consist of volcanic lavas and pyrclastic rocks, are andesitic basalt, diabase, microgabbro and dacite that were intruded by the late cretaceous granitoids. The volcanic rocks have characteristics of the calc-alkaline to tholeiitic magmatic series. The spider patterns normalized to N-MORB and Chondrite is similar to the ones belong to the supra-subduction zone (SSZ) and Islanc arcs ( IAT). The EPMA studies on the key minerals in volcanic rocks such as clinopyroxene , brought the same results. The pribable presence of an island-arc chain in the Sistan Suture Zone, which some of its parts are considered here as the MVPC, is comparable to continuation of the pakistanian Chagai-Raskoh and Kuhistan Cretaceous-Eocene island-arc/s in east. Considering this reality, we must expect to have a larger ocean much wider than what was already proposed for the Sistan Ocean as a narrow oceanic seaway in Continental rifting setting.
A Zahedi1; M Boomeri; M.A Mackizadeh
Abstract
The garnets from the KhutSkarn in the west of Yazd have been formed as a result of hydrothermal activity ofOligo-Miocene calc-alkaline plutons. The chemical composition of garnets in the Khutskarn are divided into two solid solution of grossularitic-andraditic and almost pure andradite different types. ...
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The garnets from the KhutSkarn in the west of Yazd have been formed as a result of hydrothermal activity ofOligo-Miocene calc-alkaline plutons. The chemical composition of garnets in the Khutskarn are divided into two solid solution of grossularitic-andraditic and almost pure andradite different types. The Fe-rich garnets are isotropic (Adr>96), whereasgrossularitic-andraditic garnets are anisotropic and show compositional zoning and sectorial twinning(Ad74.3Gr24.8-Ad32.1Gr66.6). The compositional zoning of anisotropic garnets may result from hydrothermal overgrowths on contact metamorphic minerals, variations in P, T, XCO2, concentrations of Fe3+ and Al, or kinetic factors. The Laser Ablation ICP-MS results show isotropic garnets exhibit LREE-enriched and HREE-depleted patterns, with a positive Eu anomaly. These garnets grow rapidly under relatively high W/R ratios from the magmatic-derived fluids during infiltration metasomatism process, whereas anisotropic garnets have much lower enrichment in LREE and show a weak negative Eu anomaly. These garnets formed by prolonged interaction of pore fluids with the host rocks during the diffusive metasomatism process.
M. Boomeri
Abstract
The Esfordi magnetite-apatite ore deposit is located in 35 Km northeast of Bafq city in Central Iran. Bafq is an important mining district which hosts more than 45 iron deposits and a few Zn-Pb massive sulfides, Mn and U deposits. The district is restricted by two main strike-slip faults of Kuhbanan ...
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The Esfordi magnetite-apatite ore deposit is located in 35 Km northeast of Bafq city in Central Iran. Bafq is an important mining district which hosts more than 45 iron deposits and a few Zn-Pb massive sulfides, Mn and U deposits. The district is restricted by two main strike-slip faults of Kuhbanan to the east and Posht e Bdam to the west. The Esfordi ores occur in an Upper Precambrian-Cambrian volcano-sedimentary complex composed of acidic tuff, carbonates, shale, and sandstone. This complex intruded by granitic rocks and basic dykes and affected by regional and contact metamorphism and hydrothermal alteration. The Esfordi magnetite-apatite ores occur on top of the acidic tuff which is near to a carbonate layer. The Esfordi deposit is the most rare-earth elements (REE)-rich and most P-rich member of the iron deposits in the Bafq district. The main minerals in the Esfordi mine are Iron oxides, apatite, actinolite, diopside, talc, andradite, feldspars, quartz and carbonates. The REE minerals are closely related to apatite and were mainly formed in or around apatite grains and within veins and veinlets. This paper identifies the REE minerals and presents preliminary information on mineral composition and geological and mineralogical features of the deposit. The REE-bearing minerals are mainly of phosphate, fluorocarbonate and silicate groups. The REE minerals are highly enriched in light REE such as Ce, La, Nd and Pr. Apatite contains a few percent REE in its composition. However, the main part of REE may be from apatite as it is the main mineral of the deposit and apatite-rich horizons contain high-grade REE ore. The metasomatic assemblage, one head crystals of apatite and many mineralized veins and veinlets indicate that hydrothermal process were definitely active in the Esfordi deposit at later stages.
M. Mohamadian; M. Boomeri; A. Ahmadi; A. A. Moridi Farimani; H. Daglas; M. Jamali
Abstract
Sungun Porphyry Copper Deposit is located about 130 km to the northeast of Tabriz, northeast Iran. This deposit contains 796 million tons of ore with 0.61% Cu, 0.01% Mo, 0.016 ppm Au, 9.75 ppm Bi and Re (0.09 wt% of molybdenite). This research studies the physico-chemical environment using the chemical ...
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Sungun Porphyry Copper Deposit is located about 130 km to the northeast of Tabriz, northeast Iran. This deposit contains 796 million tons of ore with 0.61% Cu, 0.01% Mo, 0.016 ppm Au, 9.75 ppm Bi and Re (0.09 wt% of molybdenite). This research studies the physico-chemical environment using the chemical properties of minerals of this deposit. This deposit is related to granodiorite-diorite dikes and granodiorite stock that intruded into sedimentary and volcanic rocks of Cretaceous and Eocene. Dominant alterations are potassic, phyllic, argillic and propylitic from center outward which are characteristics of continental margin porphyry copper deposits. Simultaneously with the supergene mineralization, an iron cap of iron oxides, iron hydroxides, copper oxides, sulfates, carbonates and copper phosphates were developed on top of the deposit and along the fractures. In conclusion, based on mineral chemistry, in 450 ºC and 0.5 kb pressure (PT condition of potassic zone), sulfur fugacity and pH is determined to be as: log¦S2=-18 to -24 an pH=2.5 to 7.5. In 350 ºC and 0.5 kb pressure (PT condition of phyllic zone), oxygen and sulfur fugacities are: logƒO2= -20 to -33 and log¦S2=-6 to -15.
