فهرست مطالب فرهنگ علیاری

The Mazraeh manganese deposit (southwest of Maku, north of West-Azarbaidjan Province, NW Iran) is developed in the form of scattered lenses at the contact of pillow basalts and pelagic limestones, belonging to the Khoy-Maku ophiolitic complex. Mineralogically, the ores mainly contain pyrolusite, psilomelane, manganite, and braunite which are accompanied by lesser amounts of hematite, goethite, quartz and calcite. The distribution pattern of REE normalized to chondrite along with some geochemical parameters related to lanthanides, such as La/Ce, (La/Nd)n and (Dy/Nd)n, show a hydrothermal origin for this deposit. This idea is supported by some geochemical diagrams (Co/Zn vs. Co+Ni+Cu, Zn-Ni-Co, and Mn-Fe-[(Co+Ni+Cu)]×10) and elemental ratios such as Mn/Fe, SiO2/Al2O3, U/Th, and Co/Zn. The high concentration of lanthanides in ores (on average of 767 ppm), compared to known hydrothermal manganese deposits, reveals the effects of diagenetic processes on this deposit. The occurrence of negative anomalies of Eu and Ce indicates the low-temperature hydrothermal fluids, responsible for the mineralization. The presence of detrital materials in the ores can be inferred by the concentration values of oxides like Al2O3 and TiO2.

The Neyzar lead-zinc-barium deposit is located about 20 km east of Eshgabad city (South-Khorasan Province, east Iran) and is a part of Tabas-Pushte Badam metallogenic belt. This deposit is hosted by carbonate units of Jamal (Permian) and Shotori (Triassic) Formations. Mineralization was mainly controlled by structural factors (thrust faults) in this deposit. Galena, sphalerite and barite are the principal ore minerals with minor amounts of minerals such as calcite, dolomite, quartz, fluorite, malachite, cerussite, covellite, hemimorphite, hematite, goethite, and manganese oxides. The micro-thermometric studies, using fluid inclusions, on calcite and barite crystals were carried out in this deposit. Both calcite and barite minerals are co-existed and co-genetic with Pb-Zn sulfide mineralization occurrence. Petrographic observations of fluid inclusions show that most of them are of liquid-rich two-phase type. Based upon micro-thermometric analysis, the homogenization temperatures of the fluid inclusions in calcite and barite crystals vary from 120 to 220ºC and from 119 to 199ºC, respectively. The salinities of the fluid inclusions in calcite and barite crystals also show changes within the range of 10.12-23.5 and 19.6-23.1 wt% NaCl eq., respectively. In general, the microthermometric investigations revealed that simple cooling and boiling were the main evolutionary trend for deposition of the ore and gangue minerals by sedimentary-derived hydrothermal fluids. Based on the results obtained from field observations, mineralogy, structure and texture and micro-thermometric data, the Pb-Zn-Ba deposit in the Neyzar area is very similar to those of the Mississippi Valley-type (MVT).

The main aim of mineral exploration is to discover the ore deposits. The mineral prospectivity mapping (MPM) methods by employing multi-criteria decision-making (MCDM) integrate the exploration layers. This research work combines the geological, alteration, and geochemical data in order to generate MPM in the Kighal-Bourmolk Cu-Mo porphyry deposit. The overlaying of rock units and fault layers was used to prepare the geological layer. The remote sensing and geological studies were employed in order to create an alteration layer. For generating the geo-chemistry layer, the stream sediment and lithogeochemical data were utilized. The lithogeochemistry layer was categorized into 9 ones including Cu, Mo, Bi, Te, the alteration indices (e.g. potassic, phyllic, and propylitic), and the geochemical zonality indices (e.g. Vz1 and Vz2). In addition, the stream sediment layer was categorized into 6 layers including Cu, Mo, Bi, Te, and the geochemical zonality indices (e.g. Vz1 and Vz2). By examination of the created layers, the consistency of the potential areas was verified by field surveys. Afterward, the weights were assigned to each layer considering the conceptual model of porphyry copper systems. Consequently, the layers were integrated by the fuzzy gamma operator technique, and the final MPM was generated. Regarding the generated MPM, 0.86% of the studied area shows a high potential porphyry mineralization, and these areas are proposed for the subsequent exploration drilling locations.

The sedimentary copper mineralization of the Sorkheh area is located about 20 km northwest of Marand, East-Azarbaidjan Province, northwest Iran. The most important lithologic units in this area include sandstones and red-color shales, with the Late Miocene age, that are intruded by lamprophyric dike. The copper mineralization in the study area occurred as stratiform laminations and disseminations hosted by sandstones and shales and as open-space filling textures within lamprophyric dike. The ore mineralization in the sandstones consists of chalcopyrite, bornite, chalcocite, tetrahedrite, covellite, native copper, and cuprite. This study showed that mineralization is associated with weathering and leaching of the lamprophyric dike. Also, deposition of copper in sandstone units can be related to trapping of organic matters. Activity of the hydrothermal fluids,  presence of abundant organic matters, function of diagenetic processes, existance of the geochemical barriers (organic matter and silicification), and the active tectonic in the area played crucial roles in this ore mineralization.