Search published articles


Showing 4 results for Ebrahimi Fard
Mineralogy and mineral chemistry of alteration zone in order to determine the tectonic settings and mineralization characteristics in the Choreh-Nab iron deposit (Western Alborz)
Mr Hamed Ebrahimi Fard, Dr Majid Ghasemi Siani, Dr Amir Ali Tabbakh Shabani, Ms Ma Nazarian, Dr Behrouz Karimi Shahraki,
Volume 8, Issue 2 (Autumn & Winter 2022)
Abstract
The Chore-Nab iron deposit is located in the northwest of the Zanjan-Zaker district. The deposit was formed in quartz monzonite, syenogranite, and granodiorite bodies introded into Lower Cambrian volcanic (andesite) and sedimentary units (siltstone, tuff, and ignimbrite) in the Tarom-Hashtjin metallogenic province. Iron mineralization occurs as brecciated, massive, disseminated, and vein-veinlet types. Major alteration minerals include actinolite, albite, magnetite, epidote, phlogopite, k-feldspar, and biotite. The main sulfide minerals are pyrite, chalcopyrite, and bornite. Based on field and mineralogical studies, sodic-calcic, potassic, propylitic, sericitic, siliceous, and argillic alterations have been identified in the deposit. Sodic-calcic alteration (albite-actinolite-magnetite), characterized by massive and brecciated magnetite in the depth, calcic (actinolite) and potassic (secondary biotite) alteration in the middle levels associated with vein-veinlet sulfide mineralization and finally propylitic alteration (chlorite-epidote) in the shallow levels are observed. Based on the results of chemical analyses, the clinopyroxenes in the alteration zones (mainly sodic-calcic) are mostly augite and less commonly diopside. Plagioclase has a range of albite compositions. Amphiboles are calcic and often tremolite and magnesio-hornblende. Finally, the absence of Cl in the composition of the amphiboles of the Chore-Nab deposit and the presence of at least two Cl-rich amphiboles in all the IOCG deposits of the Carajas mineral province can be attributed to the lack of influence of replacement mechanisms generated by Cl-rich hydrothermal fluids during sodic-calcic alteration.

Mineralogy of graphite-bearing schists and calculation of graphitization temperature in the Band-e-Cherk district, Anarak metallogenic zone
Dr Majid Ghasemi Siani, Mr Hamed Ebrahimi Fard, Mr Amir Hossein Heidari, Dr Behrouz Karimi Shahraki, Dr Shahryar Mahmoudi,
Volume 9, Issue 2 (Autumn & Winter 2023)
Abstract
The Band-e-Cherk exploration area is located in the structural zone of central Iran, northeast of the city of Ardestan, and the Anarak metallogenic zone. The outcropping rock units in this area include Kuh-e-Dom metamorphic schist complex and recrystallized limestone, Cretaceous limestone sediments, Paleocene conglomerate, Eocene volcanic rocks composed of andesite, andesite-basalt, trachyte, as well as tuff and diorite intrusions. The Kuh-e-Dom metamorphic complex is of lower Paleozoic age, and includes muscovite schist to graphite-muscovite schist, epidote-hornblende-calc schist, muscovite-chlorite schist, calc schist, crystalline limestone and marble. Graphite mineralization is concentrated along the schistose surfaces of graphite-muscovite schist units, and quartz, kaolinite, illite, muscovite (sericite), orthoclase and dickite minerals are other minerals. Comparison of the temperature range for the formation of high-quality flake graphite, which is formed at temperatures above 450°C, mainly between 470 and 560°C (in the amphibolite facies), with the temperature obtained by interpreting the results of Raman spectroscopy on high-quality graphite-bearing samples from the Band-e-Cherk area, shows that graphitization in the Band-e-Cherk area is of an amorphous type and at a temperature lower than 450°C (436°C). Therefore, it was formed under the temperature conditions associated with the greenschist metamorphic facies.

Microtectonic and petrofabric investigation of graphite-bearing schist units in the Band-e-Cherk district, Kuh-e-Dom metamorphic zone
Dr Majid Ghasemi Siani, Mr Hamed Ebrahimi Fard, Dr Asghar Dolati,
Volume 10, Issue 1 (Spring & Summer 2024)
Abstract
The Band-e-Cherk district is located in the structural zone of central Iran, northeast of the city of Ardestan, and the Kuh-e-Dom metamorphic zone. The schist units hosting graphitization in the Kuh-e-Dom metamorphic complex are of Upper Paleozoic (Permian-Triassic) age and include muscovite schist to graphite-muscovite schist. In the studied area, the occurrence of tectonic activities and regional metamorphism by creating deformations in the schistose surfaces containing carbonaceous organic materials, have provided suitable spaces for graphitization and increase in carbon content. Three principal phases of folding and deformation have affected the schist units. The first generation of folding (F1) and metamorphism (D1), by creating a foliation (S1) parallel to the primary bedding (S0) and the axial surface of the fold (AF1), has played an important role in the concentration of organic carbon formed during the deposition and formation of graphite. The second generation deformation (D2) is associated with the intrusion of the diorite body and variations in the dip and strike of the limestone and schist beds as well as the morphology of the district. The mylonitization of the schist units is one of the most important effects of this stage of deformation. The third and final generation of deformation (D3) has been the result of directional pressure, it has been the result of deformation, mainly in brittle form. The formation of kink band structures (in quartz-feldspar and graphite bands), jagged and dendritic edges (in quartz and feldspar crystals), subgraining (in quartz and feldspar crystals), undulose extinction in quartz, recrystallization of quartz and feldspar crystals in the muscovite schist and graphite-muscovite schist units are among the evidences of this generation of deformation in the district.

Geothermometry of skarn zones in the Tappeh Ghermez (A') iron deposit, Sangan iron mining district, NE Iran
Mr Hamed Ebrahimi Fard, Dr Majid Ghasemi Siani, Dr Behrouz Karimi Shahraki, Ms Fanoos Sharafi Nia,
Volume 10, Issue 2 (Autumn & Winter 2024)
Abstract
The Sangan mining district, the largest Fe-skarn district in Iran, is located in the northeastern part of the Alborz magmatic arc. It comprises 14 deposits (1 Gt tons and a grade of 35-60% Fe), which have an east-west trend and are divided into three parts: eastern, central and western where the Tappeh Ghermez iron deposit (A') is located in the western part. The skarnification formed near the Sarnowsar syenogranitic intrusive body, and is composed of: 1) prograde endoskarn and exoskarn zones (clinopyroxene-garnet skarn subzone) and 2) retrograde exoskarn zone (amphibole skarn subzone). Thermometry of skarnification was carried out based on the chemistry of skarn silicate minerals and their agreement with the results of microthermometry studies of fluid inclusion carried out on garnet and calcite in order to determine the physicochemical conditions and temperature of skarnification in the Tappeh Ghermez deposit. Geothermometry of the garnet-clinopyroxene pair minerals, indicated temperatures of 302 to 442°C for the prograde skarn zone. Based on the geothermometry of the calcic amphiboles in the retrograde zone, formation temperatures of 206 to 333°C have been obtained. The results of the geothermometry of the prograde and retrograde skarn zones are consistent with the results of the microthermometry of the fluid inclusions. Andradite is stable at temperatures above 430°C, even under high sulfidation conditions. At temperatures below 430°C and a relatively high fugacity of sulfur (greater than 10-6), andradite altered into calcite, quartz and pyrite. As fS2 decreases (about 10-6), such fluids form the magnetite complex.  Itcan therefore be concluded that retrograde metasomatizing fluids in the Tappeh Ghermez iron skarn deposit have a sulfur fugacity of 10-6.5 and temperatures below 430°C.

Page 1 from 1     

© 2025 CC BY-NC 4.0 | Kharazmi Journal of Earth Sciences

Designed & Developed by : Yektaweb