جستجوی مقالات مرتبط با کلیدواژه "mahoor" در نشریات گروه "زمین شناسی"

The Mahoor area is located about 135 km southwest of Nehbandan city, Khorasan Jonoobi Province, and in the central Lut block volcano-plutonic belt.  The intrusion of an Oligocene granitoid pluton with diorite, quartz diorite, quartz monzodiorite, and quartz monzonite into Paleocene-Eocene volcanic rocks that led to alteration and mineralization. Hydrothermal alteration zones consist of argillic (clay minerals), propylitic (chlorite, sericite, calcite, epidote), phyllic (quartz, sericite, pyrite), and silicification. The main ore minerals include sphalerite, chalcopyrite, magnetite, pyrite, stibnite, tetrahedrite, jamesonite, covellite, cubanite, arsenopyrite and galena, occurring as veinlets and disseminations. According to crosscutting relationships, two type of veinlet have been identified at deep levels of Mahoor deposit. Type (1) Quartz + sphalerite+ pyrite ± chalcopyrite, and type (2) Quartz +pyrite +chalcopyrite± sphalerite. The homogenization temperature and salinity of fluid inclusions in type 1 of veinlets range from 315 to 575°C and 6.8 to 21.2 wt. % equivalent NaCl, respectively. Fluid inclusions in type 2 of veinlets show homogenization temperature and salinity from 177 to 454°C and 7.9 to 20.2 wt. % equivalents NaCl, respectively. The microthermometric data indicate that the ore forming hydrothermal solution evolved through boiling events and mixing of magmatic fluids with meteoric waters. Sulfur isotopic values of pyrite and chalcopyrite vary from 1.8‰ to 3.15‰, suggesting that S was derived from a magmatic source. Geology, alteration, mineralization, fluid inclusion, and stable isotope studies indicate that mineralization in Mahoor area occurred as porphyry system.

The Mahoor area is located، about 135 km south-west of Nehbandan in the center of Lut Block. The area comprises outcrops of Eocene volcanic and pyroclastic (Eocene) that were intruded by several intrusive rocks consist mainly of diorite as dykes and stocks. Chemical classification shows that plutonic rocks are gabbro-diorite، diorite، monzodiorite and tonalite. These granitoids are high-K calc-alkaline series and they are meta-aluminous. Magnetite suitability (1485×10-5 SI) mineralogical and geochemical features show that they belong to magnetite granitoid series (I type). Enrichment in LREE rather than HREE and enrichment in LILE rather than HFSE، and typical anomalies of Nb، Ta and Ti are important evidences that show the intrusions were formed in a mamgmatic belt of subduction zone. Eu element show negative anomaly and Eu/Eu* ratios are from 0. 65 to 0. 88. Negative anomaly of Eu is due to presence of plagioclase in magma source. Geochemical studies show that Mahoor granitoids are co-genetic and they formed in subduction zone and belong to calc-alkaline volcanic arc setting in active continental margins. Mineralization is present as disseminated and hydrothermal vein related to monzonite and diorite porphyry.