Uranium mineralization in granitoids of Chah- Juleharea, Central Iran and its environmental solutions

Uranium is the main raw material for the production of nuclear energy. The development of nuclear energy significantly increases the extraction of uranium, therefore it is very important to pay attention to this metal and the environmental effects of its mining in our country.Iran's uranium deposits are mostly located in central Iran. Several deposits have been identified in this zone, one of which is the anomaly located 170 kilometers northeast of Yazd city. Chah Juleh area is located in the northeast of Yazd city and in the east of the 1:100,000 map of Ariz. It is bounded from the north by the Saghand desert, from the west by the Khashumi mountains, from the east by the Chadormello iron ore mine, and from the south by the Zarigan region (Figure 1).
The general morphology of the area is rocky and rough. This area was identified for the first time by aerial flights, during which two anomalies were identified in the north and south of the area. The anomaly in the south of the region was not followed due to the lack of surface outcrop.The development of nuclear energy will reach its peak in the next few decades. Since uranium is the main raw material of nuclear energy, the environmental problems caused by mining must be taken seriously by government agencies.

In order to carry out lithology, mineralogy and geochemical studies, about 125 rock samples (35 samples for preparing thin sections, 23 polished sections, 10 samples for X-ray diffraction analysis and about 60 samples for X-ray fluorescence analysis from the Different areas of the region, especially the mineralized points, were collected and studied .Among the alterations in the region, we can mention hematitization, chloritization, epidoteization, silicification, carbonateization, and kaolinization.Zarigan leucogranite in the studied area has been affected by Sodic metasomatism in some parts and has turned into albitite, these parts, which are seen in red color (Figure 2-b, p), have radioactivity and sometimes with a scintillometer device show the radiation intensity of 2500 cps and their radiation is related to the opaque minerals in them. These opaque minerals form a dark red halo around the opaque mineral as a result of the radioactive decay, which can be seen in the hand sample and is one of the evidences of the radioactivity of these minerals (Figure 2-P). Of course, white albitites can also be seen in the region, which do not show any special radioactivity.According to petrographic studies, Zarigan leucogranite has a porphyry to granular texture, and the samples that have been affected by metasomatism have a coarse-grained granular texture. Its main minerals include: quartz, alkaline feldspar andplagioclase. Alkaline feldspar in Zarigan leucogranite includes perthite and microcline. In the samplesaffected by metasomatism, albite mineral was formed as a result of substitution instead of alkaline feldspar and calcic plagioclase. Albit with a checkerboard pattern is one of the specialties of Sodic's metasomatism.According to mineralogical studies, the opaque minerals of albitites include titanomagnetite-dividite (Figure 2-e), which are named as U-Ti oxide phases, and their red color is due to the presence of iron oxide in the microfractures of the albite mineral.Among the secondary minerals found in leucogranite and albitites, we can mention zircon, monazite, sphene and rutile, which sphene and rutile are the result of alteration of opaque minerals.At present, the main methods of remediation of decommissioned uranium mines are to ensure the non-proliferation of pollution (Gasem Shirazi, 1401). Physical methods are used to isolate the contaminated area to prevent further damage to the surrounding environment. Conventional physical removal and chemical washing are usually expensive and can easily cause secondary damage to the environment. Phytoremediation is economical and environmentally friendly, but inefficient and limited inenrichment capacity (Gavrilescu et al., 2009). These factors make it difficult to commercialize such methods on a large scale. Uranium contamination is mainly concentrated in underground water. Considering the difficult treatment of groundwater after pollution, it is necessary to strengthen the protection of groundwater during the extraction process (Zheng et al., 2023).According to the results of the analysis of about 60 samples by X-ray fluorescence method, Zarigan leucogranite is a siliceous leucocratic rock (SiO2 W%: 76.944-78.936), peraluminous (A>CNK) and sodic (Figure 3-a) and according to the Rb diagram in Its tectonic environment is related to volcanic arcs (VAG) (Figure 3-b).Environmental solution can be done in three steps. Before extraction, the hydrogeological characteristics and chemical indicators of underground water in the mining area are carefully examined and based on this, the mine construction plan and revitalization goals are established. In the mine drilling design, the direction of underground water flow and arrangement of wells from upstream to downstream should be considered, which can reduce the halo on both sides. During the operation, the extraction volume of the leaching solution should be considered larger than the solvent injection. This can lead to negative pressure in the area and prevent the release of pollutants. After completion, a monitoring system should be set up in the vicinity, especially downstream. A periodic monitoring program should be modified to determine the range of halo emissions (Zheng et al., 2023).

Chah- Juleh area is located in the northeast of Yazd city and in the central Iran zone. The local geological setting consists up Zarigan leucogranite, quartz diorite and diabasic dykes. The Zarigan leucogranite has pervasively influenced by Na- metasomatism and has converted to albitite. These albitites are main hosted of U mineralization. U mineralization consists of U- Ti Oxide phases (Dividite- Titanomagnetite). According to geochemical studies, albitites are enriched in alcalies, Al2O3, U, Th, Nb, and REE. Also spider diagrams are shown enrichment in Ba, Th, U, Zr, Sr, Nb, Ce and depletion in zn, Cr, Ni, Rb, Pb, This enrichment reflect communion of continental crust in genesis of productive magma. Acording to field observations, petrography and geochemistry studies U- mineralization is supposed to be associated with late magmatic albitites. Uranium extraction, especially in dry weather conditions and poor drainage, can have environmental consequences, and environmental measures must be taken to prevent pollution.