جستجوی مقالات مرتبط با کلیدواژه « iron mineralization » در نشریات گروه « علوم پایه »

The studied mining area is located in the northeast of the Lut block, within the Ahangaran mountain range. The rock units in the region generally include limestone and metamorphosed carbonate rocks that are penetrated by intrusive masses with the composition of diorite, monzodiorite, granodiorite and granite. Based on the structural control of the mineralization zone and the formation of metasomatism succession with the presence of low-temperature hydrous minerals such as chlorite and epidote along with magnetite, the iron mineralization of the area can be considered as a low-temperature skarn type. The mineral chemistry of magnetite and the amounts of Ca, Ti, Al, V, Cr, Ni and Mn are also similar to skarn deposits. Field studies indicate that another younger intrusive mass at depth is the origin of the iron mineralization of the ore zone. Based on analysis of components, calculated on the basis of REE, the ore solution with magmatic origin has moved upward along the faults and after mixing with atmospheric fluids, as a result, it has created a reaction with the carbonate rocks of the iron ore.

The Qazikandi iron ore mineralization is located in the 70 km northwest of Zanjan and belongs to the Central Iran Zone. The rock units in the study area include Precambrian to Cenozoic formations as well as Cretaceous granite bodies. Iron mineralization in the Qazikandi area has occurred in the form of lensoid and vein in the basal part of the Barout Formation with carbonate and shale composition. The main ore minerals consist of magnetite, primary hematite, pyrite, secondary hematite and goethite. The secondary minerals which formed through supergene process and evolved during weathering of magnetite and pyrite are secondary hematite, goethite and lepidocrocite. The alteration in the study mineralization includes chloritization, epidotization, silicic, sericitization and argillic. The current research suggests that the intrusion of plutonic body with granite to quartz-monzonite composition into the Barout Formation has led to the formation of iron mineralization in the area. Due to the intrusion of the plutonic body into the shale parts of the Barout Formation, the hornfels developed and anhydrous minerals such as phlogopite were formed. Following the mineralization in this area, magnetite and then small amounts of primary hematite were formed. The mentioned alteration products developed simultaneously with this stage of mineralization. It is noteworthy that the silicic veins and veinlets which formed after mineralization, have cut the primary phases of mineralization. The field and microscopic evidence suggest that the Qazikandi ore deposit is classified as the magnesian skarn iron ore deposit.

The use of different geospatial layers In the exploration and determination of the mineralization zones, will lead to more reliable results. In this study, the investigation of iron mineralization zones was done using airborne magnetic data and three types of satellite images (i.e. ASTER, Landast-8 and Sentinel-2) in the Esfordi area. The reduced-to-pole filter, the upward continuation at altitudes of 200, 500 and 1000 meters, the analytic signal, the horizontal tilt angle, and the first vertical derivative were then employed on airborne magnetometry data. Argillic, phyllic and propylitic alterations, iron oxide and gossan zones and structural lineaments were extracted through satellite imagery data processing. The analytical signal and horizontal tilt angle indicators were used as the main geophysics footprints to identify the magmatic intrusions and geological lineaments, respectively. In addition, three satellite imagery indicators were used in final identification of iron-bearing zones. The weight of each layer was calculated by simultaneous analyses of the concentration-area fractal curve, the prediction-area plot, and the use of 22 Fe-bearing occurrences in the studied region. Note that the analytical signal layer with the prediction rate of 76 % has the highest weight among all layers. In other words, this layer has occupied 24% of the study area as favorable zones by which 76% of the known Fe occurrences are delineated. Iron ore potential map was prepared from integration of all geospatial indicators through the weighted multi-class index overlay method. The generated map has an intersection point with a prediction rate of 78% which has higher weight than the other individual indicators. According to this map, new iron mineralization potentials are observed in the east and southeast of the Esfordi area.

Karafs iron index is located 5Km north of the Karafs village in Hamedan province, Iran and geologically in the Sanandaj-Sirjan structural zone. Iron deposits in Sanandaj- Sirjan structural zone have been discussed and their origin is controversial. In this paper, geological, mineralogical, textural and geochemical properties, especially the geochemical behavior of rare earth elements in Karafs iron index are investigated and the mineralization type and its origin are determined.
During the field studies, 70 samples were taken for petrographic and mineralogical studies. Petrographic and mineralogical studies were performed in the Bu-Ali Sina University mineralogical laboratory. Geochemical study of iron ore was analyzed by ICP-MS at SGE company of Canada. XRD analyzes were performed at Bu-Ali Sina University.
Based on field observation,rock units in the area include volcanic rocks, phyllite, schist, skarn and limestone. Iron deposit is formed in lower Cretaceous limestone formation. The Karafs iron index consists of several small goethite-hematite sac-shaped masses which are accompanied by minor magnetite. Goethite and hematite are the main ore minerals. Most hematites formed in the ore are hypogene (first generation). Secondary hematites caused by conversion of magnetite to hematite (second generation) are very rare.
Replacement textures such as corrosion, marginal and island mainland are seen in hematite crystals. Two generations of goethite were observedin microscopic sections. The first generation goethites are macrocrystalline with an internal reflection of yellow brick and are usually amorphous and crushed and in some parts have a flowing state. Second generation goethites are found at the crystal boundaries of hematite and pyrite or fill its joints and fractures.
In the Karafs iron index, magnetite is seen with primary hematite in the form of amorphous crystals, in the size of 25 to 100 microns and with mass texture. Quartz, chlorite, epidote and sericitic are gangue minerals in the area. The correlation diagrams show positive correlation of Mg, Mn, P, Cu, Zn and negative correlation of Si, Co, Ni, Ti, V with Fe. Geochemical studies showed that the Ni / Co ratio is between 0.2 and 7, which is a characteristic of hydrothermal iron ore (Bajwah et al., 1987). Sr-Y diagram indicates that samples are plotted in the granitoid section, which shows that the hydrothermal fluids are derived from granitoid (Belousova et al., 2002). LREE is enriched in all samples. Enrichment of LREE elements related to HREE and Negative Eu anomalies in the deposit related to hydrothermal fluid have been reported in various parts of the world (Marschik and Fontbote, 2001; Galoyan et al., 2009).
Karafs iron index is located 5Km north of the Karafs village in Hamedan province and geologically in the Sanandaj-Sirjan structural zone. Rock units in the area include andesite, phyllite, schist, skarn and limestone. Iron deposit is formed in lower Cretaceous limestone formation. Goethite and hematite are main ore minerals which are accompanied by minor magnetite. The correlation diagrams show positive correlation of Mg, Mn, P, Cu, Zn and negative correlation of Si, Co, Ni, Ti, and V with Fe. Sr-Y and Co-Ni diagrams. Parameters of REE as well dispersion pattern, variance, diagrams and correlation coefficient of elements indicate hydrothermal origin derived from granitoid system and that the deposit has been hydrothermally leaching after the formation.

Kosaj Fe ore occurrence is located in the Takab‒Takht-e-Soleyman‒Angouran metallogenic zone. At Kosaj, iron mineralization occurs as lens-shaped bodies and layers parallel to the foliation of muscovite schist and actinolite-hornblende schist units (equal to Kahar Formation). Ore minerals are magnetite along with minor pyrite, and quartz and actinolite present as gangue mineral. The ore minerals show disseminated, laminated, banded, massive, lenticular, vein-veinlet and replacement textures. Three stages of mineralization can be distinguished at Kosaj. The first stage is recognized as stratiform and stratabound lenses, laminated and disseminated crystals of magnetite-quartz and magnetite-actinolite bands parallet to the foliation of host rocks. Stage-2 mineralization is recognized by folding of ore bands, σ microfabric, boudinage and elongation of magnetite crystals, quartz pressure shadows and surrounding of foliation around magnetite crystals, and recrystallization of quartz and magnetite crystals. Stage-3 is recognized by brecciated magnetite-quartz vein-veinlets. Actinolitization, silicification and hematitization are main hydrothermal alteration types at Kosaj. Chondrite-nonmineralized REE pattern of host rocks and the mineralized samples indicate that mineralized samples are depleted in REE. Characteristics of Kosaj occurrence are comparable with metamorphosed and deformed volcano-sedimentary type of iron deposits.

Baghalbid iron mineralization is one of the eastern anomalies of Sangan iron mines. This area is geologically located in the north-eastern part of Lut block. In this area, Paleozoic and Mesozoic units such as schist, phyllite and sandstone are in contact with Tertiary igneous units and Neogene sedimentary rocks. The iron mineralization occurs as hematite in the upper part of a brecciated volcanic layer with a length of more than 1 km. The footwall rocks contain breccia, tuff and sandstone and hanging wall rocks contain subvolcanic granodioritic dikes. The hematite occurs as open space filling in breccia, indicating that the iron mineralization is classified as epigenetic type. Barite, calcite, and quartz were also formed in fractures and open spaces of iron-bearing horizon. In addition to the iron, copper mineralization occurs as quartz veins containing chalcopyrite and malachite in footwall rocks. The iron oxide contents vary from 8 to 55 wt. % in the iron-bearing horizon. In mineralized rocks, the amount of chromium, vanadium and phosphorus is relatively low, while those of barium, arsenic, silver and antimony are relatively high, and LREE and LILE show enrichment relative to HREE and HFSE, respectively. According to geological, mineralogical and geochemical characteristics, ore texture and structure, REE pattern, the Baghalbid iron mineralization is classified as hydrothermal type. The iron was probably leached from pyroclastic rocks by hydrothermal fluids and was re-concentrated in the upper permeable breccia and conglomerates.

Chahpalang iron index is located in 90 km northeast of Ardakan city in Yazd province and Central Iran structural Zone. Rock units in the study area consist of meta-volcanics, recrystallized carbonates and schists. Ore body is hosted by meta-volcanics and carbonate rocks. Magnetite (two types), hematite (three types) associated with a few pyrite and secondary minerals of goethite, limonite are as ore minerals. Outcrops of orebody are disseminated, lenses and veins in the host rock. Disseminated, massive, corrosion, brecciated, replacement, network are textures of mineralization and alteration halos are chloritization, epidotization and sillicification. Total iron values vary between 28 and 91% in the samples. Low values of Cr, V and Ni-Co diagram confirm hydrothermal origin of Chahpalang iron index. REE values are between 10 and 110 ppm and distribution pattern diagram of these elements indicate the decreasing trend from LREEs to HREEs, resulting the fractionation of these elements in the hydrothermal process. Negative Ce and positive Eu anomalies and REE calculated ratios show the similarity of Chahpalang iron index with hydrothermal deposits.

Kuh-e-Ahan is a high-standing single relief within a rather flat plain, which is located in the north of the Tabas block, near the intersection of the Nayband and Kalmard faults and there are  great outcrops of  fe-oxide, along with eastern-western faults and fractures in Kooh-e-Ahan area.. The present study uses structural and remote sensing methods to discover the mechanism for evolution of the Kuh-e-Ahan, and to understand style of mineralization in the mountain, emphasizing on the role of fractures and major faults. In our remote sensing approach, we used DEM data and Aster satellite images and their filtering in main directions to detect displacements and sudden offsets of lithologic units and changes in drainage patterns. In our field studies, we studied mechanism of the faults, emphasizing on the faults within the Kuh-e-Ahan mining district. The results show N-S faults (Nayband fault trend) and NE-SW faults (Kalmard trend) have a general right-lateral mechanism, and the E-W faults are left-lateral with a reverse component. Structural model developed in this study suggest that strike-slip displacement on conjugate fault provided the space required for ascend and development of hydrothermal mineral deposits within the mine district.

Mianaj Fe ore occurrence is located in the Takab-Angouran-Takht-e-Soleyman metallogenic zone, 100 km southwest of Zanjan. In this area, Fe mineralization occurs as lens-shaped bodies parallel to the foliation of schist and rhyolitic meta-tuff units (equal to Kahar Formation). Based on mineralography, ore mineral is magnetite, and quartz present as gangue mineral at Mianaj. The ore minerals show disseminated, laminated, banded, massive, vein-veinlet and replacement textures. Three stages of mineralization can be distinguished at Mianaj. The first stage is recognized as stratiform and stratabound lenses, laminated and disseminated crystals of magnetite parallet to the foliation of host rocks. Stage-2 mineralization is recognized by folding of ore bands, σ microfabric and boudinage of magnetite crystals, quartz pressure shadows and surrounding of foliation around magnetite crystals, and recrystallization of quartz and magnetite crystals. Stage-3 is recognized by quartz vein-veinlets that cut previous mineralization stages. Chondrite-nonmineralized REE pattern of host rocks and the mineralized samples indicate that mineralized samples are depleted in REE. This signature indicates mobility of REE by Cl and F-rich oxidized fluids during mineralization processes. Characteristics of Mianaj occurrence are comparable with metamorphosed and deformed volcano-sedimentary type of iron deposits.

The study area is located in Farash 1:50000 sheet in Kerman province, at a distance of about 50 kilometers from the Jiroft-Darb Behesht road in the Jebalbarez zone. The study area is located in Bam 1:250000 sheet in the Sanandaj-Sirjan structural zone. Rock units include granite, granodiorite and volcano-sedimentary rocks combined with tuff, nummulite limestone, conglomerate and agglomerate. Due to intrusion of igneous rocks in the southern part of limestone and tuff, iron skarn mineralization is occurred. Using processing and interpretation of 1030 data ground magnetic survey with lines space of 25 meters and preparing maps of magnetic intensity and using data layers such as geological and tectonic maps, areas with potential mineralization of iron ore were introduced. After field control, it was cleared that the main outcrops of iron ore are concentrated in the central parts of the South East. The main host iron ore are skarn and granite in the middle part of the area. Trend of mineralization is NW-SE and main minerals of iron are magnetite and hematite. Iron mineralization are also occurred in zones of argillic and propylitic alteration.

The study area is located in Tertiary plutonic belt of Lut Block. Tertiary intrusive injection in Cretaceous limestone caused the formation of skarn in this region. Injection intrusive changes the texture and mineralogy of limestone and skarn or marble formed. A lens-shaped iron mineralization mainly occurred in the border of intrusions and calcareous unit. Petrological studies show that the whole combination intrusive quartz-monzonite, quartz monzonite to granodiorite variables. These granitoids are sub-alkaline series and they are meta-aluminous. Geochemical features show that they belong to I-type granitoids. Enrichment in Light rare earth elements (LREE) rather than HREE and a slight negative anomaly of Eu are important evidence that show the intrusions were formed in a magmatic belt on subductions zone and belong to calc-alkaline volcanic arc setting in active continental margins. Different geochemical graphs show consistency granitoid intrusions in south of Moein Abad with iron skarn-related intrusions

The Shakh Sefid Granitoid pluton and related Skarn are located 80 Km in the southeastern of Kerman and 20 Km north of Rayen. This area is geologically located in the southeastern of the Lut block in the Central Iran. The Shakh Sefid Granitoid with Eocene-Oligocene age cuts the Cretaceous sedimentary rocks and led to the formation of Skarn. The granitoids are granite and granodiorite in composition composing of quartz, plagioclase, orthoclase, as primary minerals, biotite as minor and chlorite and sericite as secondary minerals. The sedimentary rocks are shale, sandstone, siltstone and limestone. Metamorphic rocks are marble and Skarns. The Skarn is calcic type. Garnet (grossular-andradite), tremolite and magnetite are the main minerals that are often accompanied with hematite, goethite and limonite. Pyrite, chalcopyrite and copper carbonate (malachite and azurite) are the other minerals in Skarn. Geochemical studies show that the amount of major and minor elements of granitoid with increasing SiO2 content do not change due to the uniform mass, low dispersion of elements which result from heterogeneous textures and low alteration zone. Spider diagrams from minor elements normalized to Chondrite and primitive mantle show enrichment of all elements except for Ti, positive anomalies of Th, Pb and negative anomalies of Ti, P and Sr for the Sakh Sefid granitoids are probably due to crustal contamination. They are enriched in light rare earth elements (LREE) between 10 to 100 times and heavy elements (HREE) enrichment between 1 to 10 times compared to the reference (chondrite) and regular pattern with approximately the same slope , the parallel trends indicate that the granitoid rocks share a common source rock . The Shakh Sefid granitoid is I-type, metaluminous to peraluminous belonging to an active continental margin. Mineral and Mineralization in Kuh Shakh Sefid skarn is remarkably similar to iron skarn deposits. Minerals such as garnet and magnetite were formed in an anhydrous prograde stage at T

The Lulak Abad iron occurrence is located in the northwestern part of the Central Iran, 55 km west of Zanjan. Mineralization at the Lulak Abad area was originally identified by Zamin Gostar Company (2007), during a geophysical exploration. The present paper provides an overview of the geological framework, the mineralization characteristics, and the results of a geochemical study of the Lulak Abad iron occurrence with an application to the ore genesis. Identification of these characteristics can be used as a model for exploration of this type of iron mineralization in the Central Iran and elsewhere.
Detailed field work was carried out at different scales (give scales in parentheses) in the Lulak Abad area. About 16 polished thin and thin sections from host rocks and mineralized and altered zones were studied by conventional petrographic and mineralogical methods at the Department of Geology, University of Zanjan. In addition, a total of 7 samples from ore zones at the Lulak Abad occurrence were analyzed by ICP-OES for minor and trace elements and REE compositions at Geological Survey of Iran, Tehran, Iran.
Rock units exposed in the Lulak Abad area consist of schists and metavolcanic units the Kahar Formation; Lotfi, 2001) that were intruded by granite and microdiorite bodies. The schist units consist of chlorite-biotite-muscovite schist and muscovite schist that show granolepidoblastic texture with foliation-parallel disseminated magnetite. The metavolcanic units consist of metadacite, rhyolitic metatuff and meta-andesite with porphyritic textures. They are marked by dominant mylonitic foliation surrounding feldspar and quartz porphyroclasts. Alkali feldspar and quartz are the principal minerals of the granite. The intrusion is characterized by intense deformation features and is highly mylonitized. Based on field and microscopic studies, the microdiorite postdated metamorphic and deformation events and shows neither schistosity nor mylonitic foliation. It is composed principally of plagioclase with minor disseminated magnetite and a microgranular texture. Two deformation events are recognized at the Lulak Abad area, one principally ductile, the other brittle.
Iron mineralization at Lulak Abad occurs as veins, veinlets and lens-shaped bodies in schist units, mylonitic metavolvanic rocks and mylonitic granite. The main ore vein extends up to 100 m in length and averages 3 m in width, reaching a maximum of 6 m. It trends NE, dipping steeply SE. The ore lenses are parallel to the mylonitic foliation and variably boudinaged, about 10 m in length and vary in thickness up to 5 cm. Two stages of mineralization can be distinguished at Lulak Abad. Stage 1 mineralization is recognized as stratiform and stratabound lenses, laminated and disseminated crystals of magnetite in volcano-sedimentary host rocks. Stage 2 is characterized as hematite-pyrite-calcite veins and veinlets cutting the mylonitic foliation of the host rocks. Hydrothermal alteration is restricted to silicified, calcitic and chloritic altered parts of the ore zones.
The ore minerals at Lulak Abad formed as vein and hydrothermal breccia cements, and show vein-veinlet, brecciated, disseminated and open space filling vein and veinlet textures. Hematite is the main ore mineral, accompanied by minor magnetite and pyrite. Goethite occurs as a supergene mineral. Quartz, calcite and chlorite are present in the gangue minerals that represent vein-veinlet and vug filling textures.
The Lulak Abad mineralized veins and breccias show lower concentrations of LREE and HREE (i.e., Pr, Er, Ho, Dy and Yb) relative to barren granitic host rocks but higher Tm, Gd, Eu and Lu concentrations. Chondrite-normalized REE patterns (Sun and McDonough, 1989) of host barren granite and the mineralized samples at Lulak Abad indicate that mineralized samples are depleted in LREE (except Ce) but enriched in most HREE (beside depletion in Dy and Ho). These signatures indicate high wall rock interaction (e.g., Lottermoser, 1992; Liegeois et al., 2003).
Comparison of the geological, mineralogical, geochemical, textural and structural characteristics of the Lulak Abad occurrence with different types of iron deposits reveals that iron mineralization at Lulak Abad was originally formed as volcano-sedimentary, and then reconcentrated as vein mineralization (Karami et al., 2012; Karami et al., 2013).