محمدرضا هزاره

due to the increasing progress of today 's technology and the use of rare earth elements and strategic elements of these elements as well as the need of the country 's industry to these elements, the study and discovery of these elements is of great importance. Senj polymetal deposit is located 57 km northwest of Karaj city in Alborz province and in the central part of Alborz magmatic arc. In this region, the magmatic mass from monzonite to monzodiorite is of Oligocene age and due to the Middle Alpine orogeny phase, it has been injected as a sill into the igneous rocks of tuff to andesite-tuff porphyry. The geochemical investigations of the deposit show that the concentration of some elements such as molybdenum, copper, gold and rare earth elements is exceptionally high. One of the remarkable points in this deposit is the high anomalies of light rare earth elements (Ce, La) as well as Y, Th elements. The concentration of La in high grade samples varies from 400 ppm up to 23700 ppm and Ce from 420 up to 37900 ppm. Rare earth elements are mainly concentrated in two minerals, allanite and apatite. The comparison of 34S δ sulfur isotope changes in the Senj deposit with the ore-forming type of sulphide deposits showed that it is most compatible with volcanic-hydrothermal deposits.

Nineh Pb-Zn deposit is located in the east of the Markazi province, in the Middle to Upper Jurassic rock units of the Malayer-Esfahan  metallogenic belt. Stratified and epigenetic mineralization, in the form of veins, replacement and open spaces filling, including the main minerals of galena, sphalerite and barite accompanied by dolomite and siliceous alterations are observed. The microthermometry results of fluid inclusions in calcite and barite, display mean homogenization temperature of about 168.6°C and 127.3°C, and a mean salinity of 5.7 and 13.9 wt. % NaCl equiv., respectively, which indicates slight difference in their formation conditions. The homogenization temperature versus salinity diagram suggests a basinal brine fluid mineralizer and mixing and cooling processes for the mineralization. The values of δ34S in galena and sphalerite (7.5‰ to 21.5‰) of this deposit are similar to the values of δ34S in the upper Mississippi deposits, indicating the supply of sulfur during the process of thermochemical reduction of sulfate. The values of δ18OSMOW (-9.2 to -11.2‰) and δ13CPDB (0.1 to 0.5‰) of the calcite veins indicate a multi-origin of oxygen, and the origin of carbon from dissolved and remobilized marine carbonates. According to the evidence obtained during this study, the Nineh deposit can be classified as the Mississippi Valley type deposits, which was formed during the orogeny processes and the movement of basinal brine  fluids.

The Esfordi deposit is located at northeastern Bafq and is one of the well-known magnetite-apatite deposits in the area which consists of ore minerals hosted REE. Among the various ore minerals, apatite is one of the unique minerals because of its significant properties such as providing a budget of elements (especially in the case of REE), stability over widespread temperature and pressure domains and exclusively ionic interchanges as a respond to re-equilibrium with new environment. All of which can fit the apatite as a main source feeding the new mineral nucleation like monazite during a hydrothermal alteration. Based on petrography and geochemistry studies, mineralization of four generation apatite accompanied with dropping of REE amount in each stages and increasing of residual Ca and P in the next generations. In contrast, culminating amount of REE beside Na, F and limited Cl reached in nucleolus monazite and led to the formation of two generation of monazites. On the BSE images of apatite, the depleted areas are associated with micro-channels and micro-pores containing monazite. Consequently dissolution of nucleolus monazites provides a well chance to form the second generation of monazite as bigger grain than the first ones.

The Urmia-Naqadeh-Mahabad basin is a part of the south and west Urmia Lake drainage basin that covers some parts of East-and-West Azerbaijan and northern Kurdistan. This study is the integration of geological, hydrological, remote sensing, geochemical and airborne geophysical data classifying promising areas that are related to sandstone type uranium (U) mineralization in Iran. Based on positive factors such as favorable source, host rocks and suitable hydrological pattern, this basin is a favorable basin in Iran. According to the characteristics of lithology, tectonic, sedimentary environment, geotectonics and etc. the basin could be classified into favorable, promising and possible subbasins for mineralization of U sandstone type.
Material and Geological data show that this region is a part of the Sanandaj-Sirjan zone and consists of Precambrian metamorphic rocks which are covered by younger sedimentary and volcano-sedimentary rocks that are influenced by different metamorphic phases. More than 7597 stream sediment samples from the area have been analyzed for Se¡V¡ Mo¡ As¡Cu¡ Ag¡ Zn¡ Co¡ Ni¡ Pb¡ Ti¡ Th¡ Zr¡ P and Sn. The basin is divided into 11 individual sub-basins. Radiometric data of the basin have been acquisitioned during 1976-1978 by an Australian-German- French Company with line separation of 500 meters and 120 meters of nominal terrain clearance.
Remote sensing data reveals that the western subbasin is suitable for sandstone type uranium mineralization. Based on geochemical evidences, the Au, Zn, Sn, As and Pb elements were enriched. Geophysical investigation reveals that the Eastern basin includes high amounts of U and low amounts of Th. Hydrogeological study demonstrates that the trend of groundwater is from the west to the east.
Geochemical data revealed that we can divide the basin into 11 subbasins which are characterized as follows: 1. Ghara Aghaj (126 Km2), North to south trend is situated at the northern part of the basin. At this basin Ni, Co, Cu and V are reported but it is not related to mineralization.
2. Ghoma – Bezrgah (36 Km2). The East to the West trend is situated at the western part of the basin. At this basin Pb, As, Sn, Zn and Au are reported which can be related to skarn mineralization.
3. Piram – Shilan (342 Km2). At this basin Pb, Zn, As and Mo are reported which contain source rocks of uranium mineralization but there is no evidence of host rock and mineralization.
4. Pirestan1 (28 Km2). According to geological data a granitic body which can be the source of uranium mineralization and cretaceous volcanic rock outcropped. The fault system is weak by the north to the south trend. The anomalies of Pb, Mo, As and Sn are reported but there is no evidence of mineralization.
5. Kooh-e sabz poosh (34 Km2). Based on geological data half of the area is covered by granodioritic body which can be the source of uranium mineralization. The fault system has two trends (NE-SW and N-S). The anomalies of V, As, Mo and Co are reported but there is no evidence of mineralization.
6. Pirestan2 ((83 Km2). According to geological data a granitic and granodioritic body can be the source of uranium mineralization. The anomalies of Mo, Sn, Co, As and Zn are reported but there is no evidence of mineralization.
7. Chahar Taq (36 Km2). The fault system has the NE to SW trend and trusted mechanism. The anomalies of Zn, Ni and Au are reported but there is no evidence of mineralization.
8. Zaveh Kooh (111 Km2). The rock units have the NW to SE trend according to the Sanadaj-Sirjan trend. The anomalies of Pb, As, Sn, Mo, Ti, Cu, Ni and Au are reported but there is no evidence of uranium mineralization but there is some evidence of orogenic gold mineralization.
9. Saqqez-Baneh (465 Km2). The rock units have the NW to SE trend according to the Sanadaj-Sirjan trend. The anomalies of Co, Ti, Cu, Zn, Pb, Ni, Mo, Sn, Ag, Au and As are reported but there is no evidence of uranium mineralization and the same as the 8th subbasin there are known deposits of orogenic gold mineralization.
10. Charkeh (104 Km2). The rock units have the NW to SE trend. The anomalies of Zn, Mo, Sn, V, Ni, Au, As and Pb are reported but there is no evidence of mineralization.
11. Sheikh Ebrahim (38 Km2). The anomalies of Mo, Au, As and Pb are reported.
The integration of the different layers shows that the prospecting area is suitable for future exploration of blind deposits.
Geophysical data was processed and revealed those areas which have data. They can be classified into 5 different classes based on U and Th concentrations.
The Hydrogeological data consist of EC, pH, Eh, DO and salinity. And the temperature was measured at the field by Sension 156 multimeter and was sent for ICP-MS analysis to the AMDEL and Applied Geological Research Center (Karaj) laboratories. Two samples were obtained from each well by Widel et al.’s (1998) method. One sample was analyzed for Ca2¡ Mg2¡ Na¡ K¡ CO32-¡ HCO3-¡ SO42-and Cl- and the other samples were analyzed for major and trace elements. At each basin charge, the discharge and the trend of underground water were defined.
The results revealed that this basin contains alkaline magmatic rocks such as alkaline rhyolite and tuff which are situated in reduced shale and continental volcanic clastic rocks and can be the source of uranium at the study area. Besides these rocks, tuffaceous sandstone, metamorphose sandstone and young alluvial by the reduction condition can be the suitable hosts for mineralization.
Based on geological, geochemical, hydrogeological and geophysical data, the western basin is suitable for sandstone type uranium deposit and also there is some evidence of mineralization.

Based on studies, Kervian gold mineralization is known as the shear zone type. Gold mineralization in this area has been controlled by factors such as plastic shear zones and hydrothermal alteration. Dominant alterations are chloritic and sericitic, and in some places silicic and carbonatic alteration are seen. Hence, geochemical comparison of non-altered rocks with altered rocks in the region will help to evaluate the effects of alteration process on the element scattering and investigate geochemical behavior of elements. Geochemical behavior (kind and rates of mobility) can be defined as a quantitative measure to evaluation of mineralization area. Isocon method is defined based on process where the immobile variables identified, and according that element by loss and gain behavior is separated. Numerical calculations were carried out to recognize mobile or immobile elements in various rock units (Intrusive rocks, metavolcanic and shear zone) and also different ratios of these elements in altered and non-altered area showed that elements of Al, Ti, and rarely Na, Cr having immobile behavior, and their masses was relatively unchanged during alteration. As, La, Mo, Ba, Mn and Au was added and As in shear zone part showed maximum mass gain. Also Zn, Ca, Sr and Mg were depleted in all kind of rocks. Exploration ratio which show distal and proximal to mineralization area, constructed from the total abundances of added element to depleted element, and according this survey exploration index is defined

The gold mineralization in Kurdistan Province of Iran was classified as shear zone gold type by some of the researchers. In the current study, the geochemical samples collected from the secondary environment, stream sediments, at the SW of Saqquez area were used to investigate the geochemical characteristics of the gold mineralized zones in this environment. The multi-variant statistical analysis, cluster analysis, was used to identify the gold paragenesis. The cluster analysis was led to identify the geochemical paragenesis of Au, which are W, Bi, Sn, and Hg. Hg, and Sb haloes are extended in un-mineralized area. As element, which is an important paragenesis in many gold deposits, was used instead of Hg in this investigation. The anomaly areas for each element were determined based on the probability plot modeling method. The spatial dispersion haloes of the anomaly areas, as 2D map, were identified based on the modeling of probability plot results. The results of interpretations were shown that Sn, W and Bi were highly correlated with Au in the study area. Element of As did not show an important correlation and anomalous area in this environment. These characteristics show a very high correlation to the primary dispersion haloes of shear zone gold deposits in the other part of the world. Based on these similarities of the behaviors, the other geochemical exploration patterns in the primary environments might be used for the Kurdistan mineralized areas to prioritize the anomalous area for follow up exploration.