Rezvan ore deposit, northeast of Rafsanjan: a volcano-sedimentary iron mineralization in the Rizou series, Poshte Badam block

Document Type : Research Article

Authors

Mohammad Reza Ardyani ¹

Fardin Mousivand ²

Mahmoud Sadeghian ³

¹ M.Sc. graduate in Economic Geology, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran

² Associate Professor of Economic Geology, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran

³ Associate Professor of Petrology, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran

10.22067/econg.2026.96025.1160

Abstract

The Rezvan iron deposit is located in Kerman province, 28 km northeast of Rafsanjan. This deposit is located in the Central Iran Zone and in the Poshte Badam block. Stratigraphically, the host rock units belong to the Late Proterozoic Rizou series. The rock units from bottom to top include shale, sandstone, limestone, basaltic tuff and lava, stromatolite limestone, white quartzite, and massive dolomite. Iron mineralization has occurred in a specific stratigraphic horizon as stratiform and stratabound. Considering the structure, texture, and mineralogy, the orebodies have a layered facies at the top and a vein-veinlet facies at the bottom. The main minerals of the ore include magnetite, oligist/specularite, pyrite and chalcopyrite. Based on field observations, hand sampling and microscopic studies, the important structures and textures identified in the deposit include massive, banded, brecciated, vein-veinlet, disseminated and replacement. Chloritization and epidotization in the host and footwall tuff units are the most widespread alteration and other minor alterations are silicic and sericitic. Based on studies of structure, texture, mineralogy, alteration and precedence and delay of mineral veins in the footwall, three main phases of mineralization can be recognized in the Rezvan deposit. The first phase, in the form of first-generation veinlets, are mainly composed of quartz (with minor amounts of pyrite) and is siliceous in nature, which probably indicates lower temperature and higher pH conditions of the fluid. The second phase, which is the main phase, consists mainly of magnetite with pyrite, epidote, chlorite and phlogopite and sometimes vermiculite, hornblende and actinolite, and indicates higher temperature and lower pH. The third phase, in the form of third-generation carbonate ore-bearing veinlets, contains some magnetite, pyrite and sometimes oligist/specularite and silica, which seems to have lower temperature than the previous phase and higher pH and Eh. Based on lithogeochemical studies, according to the normalized diagram to chondrite, the europium anomaly is negative, indicating formation of the ores in a shallow and oxidizing environment. Based on geochemical studies on stringer, massive and banded ore facies, the amount of Zn, V, Ni, Co, Mn and As elements increases from the stringer section towards the massive and banded facies, while the amount of Sr and Ti elements decreases. The ore samples of the Rezvan iron deposit are geochemically within the range of volcanic-sedimentary deposits.
 
Introduction
Access to the area is via the Rafsanjan asphalt road towards Zarand. This area is located 2 km north of the Odarj village. The Rezvan mine is located in the northern part of the 1:100,000 Davaran map (Vahdati Daneshmand et al., 1995). This exploration area is located in the Central Iran Zone and in the Poshte Badam block in the Central Iran zone (Alavi, 1991). A detailed scientific study of the iron mineralization of this area has not been conducted, which is major aims of this research.
 
Materials and methods
For geological, mineralogy, and alteration studies in the study area, in addition to field studies, 8 thin sections for petrographic studies of host and associated rocks, 4 polished sections, and 34 thin-polished sections were prepared and examined. In addition to microscopic studies, 3 samples from alteration zones were also selected and studied by X-ray diffraction (XRD) to detect some altered minerals. Also, to conduct geochemical studies of the host rock units of mineralization, 24 samples were sent to Zarazma Company for Inductively coupled plasma mass spectrometry (ICP-MS), and the results were examined.
 
Result and discussion
Iron mineralization in the Rezvan region of Rafsanjan occurred in the Rizou series with a Late Proterozoic age range, which mainly involves felsic tuffs and basaltic lava units with carbonate interlayers at the top of the sequence. Iron mineralization occurred in specific stratigraphic horizons, mainly in tuffaceous units and to a very small extent in the granitoid intrusion. The orebodies are layered in nature and have a vein-veinlet facies in the lower part, and massive and bedded ore facies at top. In the vein-veinlet/stringer facies, the ore-bearing veins-veinlets are accompanied by chlorite-epidotic and siliceous alterations. The massive ore facies forms the high-grade part of the deposit, and the banded facies involves alternations of iron oxide-rich and iron oxide-poor layers within tuff units. The main ore structures and textures include massive, banded, brecciated, vein-veinlets, disseminated and replacement. The main minerals of the ore include the primary minerals of magnetite, pyrite and some chalcopyrite and oligist/specularite, and the secondary minerals such as hematite and goethite. Based on lithogeochemical studies on the stringer, massive and banded facies, the amount of Zn, V, Ni, Co, Mn and As elements increases from the stringer section towards the massive and banded facies, and, however, the amount of Sr and Ti elements decreases from the stringer facies towards the banded facies. Based on lithogeochemical studies, according to the normalized diagram to chondrite, the europium anomaly is negative, indicating formation of the ores in a shallow and oxidizing environment. Various evidences, including the type of host and associated rocks, the morphology of ore bodies, the structure, texture, and mineralogy of ore and alteration, indicate that iron mineralization in the Rezvan deposit in the Rizou series was similar to the volcanic-sedimentary iron deposits that were deposited during the Late Proterozoic period due to the activity of submarine hydrothermal systems. The volcano-sedimentary iron deposits and banded iron formations, which are the largest sources of iron, are widespread throughout the world (e.g. Hou et al., 2014; Wu et al., 2015; Wu et al., 2016). In addition to other types of iron deposits, Iran is also prone to volcanic-sedimentary iron deposits (Nabatian et al., 2015). Similar deposits involve the iron mineralization in the Hormuz series on Larak Island (Alizadeh Fard and Mousivand, 2023) and the iron-celestite-manganese mineralization of Kuhe Rig (Mahdevari et al., 2021).
 
Acknowledgements
The authors would like to thank and appreciate the Shahrood University of Technology and the manager of the Rezvan Iron Mine Company, Mr. Mohammadi, for supporting this research.

Keywords

iron

volcanic-sedimentary

Rizou

Poshte Badam Block

Rafsanjan

Rezvan

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