جستجوی مقالات مرتبط با کلیدواژه « بافق » در نشریات گروه « زمین شناسی »

Petrographic and mineralogical data indicate the widespread presence of five generations of apatite, two generations of monazite with minor xenotime in the Esfordi deposit. The O-H isotopic studies on the 1st- and 2nd-generations of apatites and massive fine-grained and vein-type apatites as well as their Sr and Mn contents, showed that the source of phosphorous was the sedimentary phosphorites. The ratio of 143Nd/144Nd vs 147Sm/144Nd and εNd vs P2O, and the difference of Nd isotopic ratios in the massive fine-grained and vein-type apatites indicate that they are not reproductively related to the host rhyolite and diorite. The similarity of 143Nd/144Nd vs 147Sm/144Nd and εNd vs P2O5 in the 1st- and 2nd-generations of apatite and the host rocks indicated that recrystallization of the apatites occurred during the magmatic and hydrothermal fluids circulation which were derived from the felsic to intermediate subvolcanic rocks. Difference in the age of the 2nd-generation apatites and the paragenetic- monazites ( 238U/206Pb and 207Pb/206Pb dating), the crystalline apatites and magnetite, the ilmenite exclusions in the magnetites, the dissolution evidences of different apatites and monazites generations, the content of Ti vs V, Al+Mn vs Ti+V and Mg+Al+Si vs Ti, and the O-H isotopes of the magnetite-apatite ores, all indicate the mixing of high-temperature magmatic and hydrothermal fluids rich in REE, P with Ca ±Fe evaporatic brines in different time periods, which caused a polygenic origin for the Esfordi deposit.

Many mafic dykes, with the Early Paleozoic age, have intruded into Zarigan granitoid pluton and its host sedimentary units in the northeast of Bafq city. Petrographycal studies show these dykes are alkaline gabbro to monzogabbro with medium to fine grain intergranular to granular textures. Major minerals include clinopyroxene, amphibole and plagioclase and minor minerals are a few amounts of biotite, olivine, alkali feldspar, and nepheline. Amphiboles are calcic and belong to kaersutite-potasic kaersutite type. Geothermo-barometry calculations, based on amphibole mineral, show the prevailing pressure and temperature of kaersutites crystallization at 6.3-8.2 Kbar and 1040-1140 °C. According to geochemical composition, kaersutites are in the range of alkaline amphiboles, so that they are derived from mantle and are related to intercontinental extensional tectonic environment. Based on these evidences, minerals have been crystallized from the magmas originated from asthenospheric upwelling during Paleo-Tethys early rifting and associated with Posht-e-Badam block basement tension faults function.

Subduction-related magmas are characterized by enrichment of large ion lithophile elements (LILEs), light rare earth elements (LREEs) and depletion in high field strength elements (HFSEs) (Harangi et al., 2007). These geochemical signatures of magmatic rocks are commonly explained by the addition of hydrous fluids from subducting oceanic lithosphere combined with the flux of melts from subducted sediments to the mantle wedge, lowering the mantle solidus and leading to magma generation (Aydınçakır, 2016). Asthenospheric mantle, subcontinental lithospheric mantle and/or lower crust may be the principal source of these rocks (Eyuboglu et al., 2018). In addition, magma differentiation processes, such as fractional crystallization, crustal contamination, and magma mixing may also play an important role in the genesis of these rocks.This research study presents new petrological and geochemical data from the volcanic rocks with NW–SE trending, which are situated in the northwestern margin of the Central –East Iranian Microcontinent (CEIM) (south-east of Khur, Isfahan Province) which have been formed during the peak activity of Eocene. Study of this typical small volume subduction- related magmatism will be useful in understanding the origin and geological evolution of the Central Iran in Cenozoic.

The petrographic investigations on Eocene volcanic rocks from the SE of Khur area were carried out with an optical microscope (Olympus-BH2) in the petrology Laboratory of the University of Isfahan, Iran. Major and trace element concentrations of samples from whole- rocks were obtained by a combination of inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) at the Als Chemex Laboratory of Ireland. The chemical compositions of 4 samples (B865, B866, B867, and B868) were determined by Neutron Activation Analysis (NAA) in the Isfahan Activation Center The detection limit was 0.01% for all major element oxides and 0.01 ppm for rare earth elements. Mineral abbreviations were adopted from Whitney and Evans (2010).

Eocene volcanic rocks with trachy-basalt and trachy-basaltic andesite composition are exposed in the northwestern part of the Central-East Iranian Microcontinent (CEIM) (SE of Khur, Isfahan Province, Central Iran). These rocks which have a dominant northwest-southeast trend crosscut the Cretaceous sedimentary rocks.Petrography and mineral chemistry analyses indicate that the predominant rock-forming minerals of volcanic rocks are olivine, plagioclase, clinopyroxene and orthopyroxene. Phenocrysts set in a fine to medium grained matrix of the same minerals plus sanidine with minor amounts of opaque minerals. Secondary minerals are chlorite and calcite. The most common textures of these rocks are porphyritic, microlitic porphyritic, poikiolitic and glomeroporphyritic. Geochemical analyses of whole rock samples show that these rocks have been enriched in alkalies and large ion lithophile elements (Cs, K, Rb, Sr, Ba,), and have been depleted in high field strength elements (HFSE) (Ta, Nb, Ti). All samples indicate moderate to high fractionation in LREE patterns. These geochemical signatures point out to the subduction-related calc-alkaline nature of these rocks and their similarity to volcanic rocks of continental arcs or convergent margins (Yu et al., 2017). Pb enrichment and low values of Nb/La, Nb/U and Ce/Pb ratios reveal that crustal contamination has played an important role in magma evolution (Srivastava and Singh, 2004; Furman, 2007). The large volume of hydrous fluids coming from the subducted slab rather than sediments have caused enrichment and metasomatism of the subcontinental lithospheric mantle source. The geochemical characteristics of the studied rocks suggest that the parental magma have been derived from partial melting of a metasomatized spinel lherzolite of lithospheric mantle, which was previously modified by dehydration of a subducting slab. The tectonic environment, in which these rocks were formed has probably been a volcanic arc. Subduction of oceanic crust around the Central-East Iranian Microcontinent (CEIM) is the most reasonable mechanism which can be used to explain enrichment in volatiles of the mantle, and the calc-alkaline magmatism of the study area in Eocene times.

Anomaly XVI-B located in Central Iran Structural Zone. The oldest rock formations in this study area are related to metamorphic rocks which are included gneiss, micaschist, amphibolite and megmatite. Mineralized intruded mass distinguished by alkaline diorite-syenite that cut Bonoshorow metamorphic complex and limestone units. Metallic mineralization is occurred in syenite, gabbro and skarn rocks. Magnetite is the most abundant mineral in anomaly XVI-B and also it has been seen as stripe, mass, disseminated and filling empty space textures. The magnetite grains are shaped to shapeless. Magnetite is oxidized near the surface and converts to hematite, goethite and other iron oxides. Another metallic mineral which are associated with magnetite are pyrite, and chalcopyrite, which have been found in quartz, actinolite, calcite, and epidotite that come with various forms within host rocks, syenite, gabbro, and skarn. According to the graphs of rare earth elements in iron mineralization and intruded units indicates the possible similarity of the source of iron mineralization with intruded mass. The grade of iron oxide in ore deposit varies between 25 and 75 percent. The iron element has a negative correlation with oxide of titanium oxides, magnesium, manganese, phosphorus, potassium and sodium. Based on cobalt relationship with nickel, chromium - nickel, and chromium - vanadium, so anomaly XVI-B iron deposit is related to the hydrothermal deposits. Due to the ratio of Al / Co and Sn / Ga, anomaly XVI-B is recognized as a skarn type deposit. Based on the scattering patterns of the rare elements, anomaly XVI-B is more similar to the skarn type deposit. Geological and mineralogical evidence, as well as the geochemical properties of the magnetite, indicate that skarn deposit is source of iron mineralization. Iron is transported by the hot fluids that come from intruded units that accumulates between boundary of metamorphic and marble units. δ34S value is between 21.24% - 22.27%. The source of Sulphur isotope is meteoric and ancient marine water. As a result, the accompaniment of magnetite with pyrite can be found that the source of magnetite is identical with pyrite.

The Ti- Fe mineralization in Bafq 15 anomaly located 35 Km NW of Bafq city, and is a part of Poshte Badam Block in the Central Iran. Mineralization including magnetite, titanomagnetite, ilmenite, and minor pyrite which hosted by gabbro and pyroxenite intrusions syngeneticly. Based on the whole rock chemistry, FeOt, TiO2, CaO, Ni, Cr and V show a positive correlation with MgO, whereas Al2O3, Na2O+K2O, and SiO2 display a negative correlation. These correlations are in agreement with the crystallization of clinopyroxene, amphibole, plagioclase, and oxide minerals in the intrusion. The positive correlation of V, Cr, and Ni with Fe indicates the concentration of these elements in Fe minerals. The chemical composition of ore minerals mostly plots in the solid solution of magnetite- ulvospinel (titanomagnetite) and magnetite- ilmenite fields. In QFM+1> conditions, the high Fe-Ti contents along high H2O content (>2 Wt. %) of parental magma are the most prominent factors controlling Fe- Ti mineralization. According to the proposed model for mineralization, as a new pulse of magma enters the chamber, the high H2O content sufficiently depressed the crystallization temperature of silicates in analogy to oxides, giving rise to early crystallization of Fe-Ti minerals. Increasing of H2O content and magmatic volatiles during magma fractionation consequently may induce immiscibility and separation of oxides from residual melt in late magmatic stage whereas this dense oxides melt flow through pre-crystalized silicates and solidified as intercumulus phase.

REE should be evaluated in rocks and minerals due to their behavior in complex geochemical processes leading to their use as tracers in geochemical environments. In addition, the lack of economic concentration of these elements is related to their contribution in rock forming minerals. Thus, high levels of technology and costs are essential for their extraction. However, REE minerals can be formed under special geological conditions. In this regard, the Esfordi iron-phosphate deposit is interesting both economically and scientifically. The present study is aimed at determination of rare earth element mineral types, along with their occurrence in this deposit by using mineralogy, geochemistry, and fluid inclusion microthermometry methods.

Method of study:

A total of 42 apatite samples were taken from different lithological units and ore-bearing veins. Following petrographic observations, 10 and 6 representative samples were analyzed using SEM and XRD methods in the Iran Minerals Processing Research Center, respectively. Geochemical properties of apatite and rare earth element minerals were determined on 8 samples using LA-ICP-Ms at the University of Tasmania, Australia. Moreover, the same was done for 6 samples using EPMA at the Geo Forschungs Zentrum Telegrafenberg of Potsdam University, Germany. In addition, 12 samples of apatite were considered for evaluating petrography of fluid inclusions. Microthermometry of the fluid inclusions was conducted on two second generation apatite samples associated with massive phosphate mineralization zone and magnetite mineralization zone in the laboratory of the Geological Survey and Mineral Explorations of Iran. Phases changes in fluid inclusions in heating and freezing tests under a Linkam THM600 microscope with TP94 Thermal Controller and LNP Type Cooler mounted on Zeiss microscope, with an accuracy of ±0.5 ˚C was performed. Given that no phase changes were produced in some inclusions (melt inclusions) up to the temperature of 600°C, two samples of apatite were studied using the Linkam TS1400XY microscope in Lithosphere Fluid Research Lab of the Department of Petrology and Geochemistry at Eötvös Loránd University, Budapest, Hungary.

Mineralogical studies of apatite in Esfordi revealed the extensive presence of monazite and a lesser amount of xenotime. The results indicate two generations of monazite in this deposit. The first generation is observed as inclusions within the apatites, while the second generation occurs along the fractures of apatites. Monazite inclusions are abundant in the dark phase of host apatites. Based on geochemical data, the second generation of monazite is enriched in La, La/Ce, Nd, and Pr compared to the first generation. Furthermore, strong negative correlation coefficients were observed between Ca, P, and ΣREE, while a positive correlation was reported between Si and P in apatite and monazite. Chondrite normalized spider diagrams indicate a negative slope (LREE/HREE>1) in all of the samples. Moreover, a strong negative correlation was observed between Sr and Y in the studied apatite and monazites. Fluid inclusions within the apatites were classified into eight groups: a) one-phase gaseous inclusions, b) one-phase liquid inclusions, c) two-phase liquid rich inclusions (L+V), d) two-phase gas-rich inclusions (V+L), e) two-phase liquid- solid inclusions (L+V), f) three-phase inclusions (V-L-S), g) three-phase CO2 bearing inclusions associated with formation of clathrate, and h) melt inclusions. The composition of the fluid inclusions is plotted in magmatic and hydrothermal fields. The salinity of most of the inclusions is low to medium (5-21 wt.% NaCl) and homogenization temperature ranges from 250 to 350˚C. Also, a limited number of fluid inclusions were homogenized in the range of 378-486 ˚C, indicating high salinity (43 to 54 wt.% NaCl). The fluid trapping depths were measured to be in the range 100-1700 m.

The Esfordi iron-apatite deposit is located NE of Bafq, Yazd province and it hosts three types of apatite mineralization in massive, vein, and disseminated forms, as well as REE-bearing minerals. Periodic variations in mineralizing fluid is evidenced by changes in REE content of the studied minerals. The presence of monazite in dark phases of the host apatite mineral indicates leaching of REE from the host apatite and redeposition during the nucleation of monazite grains (Heidarian et al., 2017). Mineralogical data indicated that the apatites are of the fluorapatite type with minor contents of chloride (Rajabzadeh et al., 2013). The quantities of Sr and Y in the studied minerals indicate a strong negative correlation, consistent with magmatic differentiation. In addition, the concentrations of Mn, Sr, and Y support the granitoid origin of the Esfordi deposit (Belousova et al., 2002). Microthermometric data plotted on magmatic and hydrothermal fields indicated that mixing fluids and boiling are the important factors in mineralization. Upon the obtained data of the present study, main parts of the Esfordi iron phosphate deposit have been formed at temperatures ranging from 146 to 486˚C and depths of 100 to 1700 m.

The mafic- ultramafic intrusion in the Bafq anomaly Iron located 35 Km northwest of Bafq city, Central Iran. The 15th anomaly intrusion intruded the Rizu sequence series, stratigraphically attributed to early Cambrian magmatism in the west of Posht-e- Badam block. The Rizu sequence series is composed of carbonate rocks of upper Neo-Proterozoic-early Cambrian. The mafic-ultramafic intrusion is dominated by amphibole-gabbro, apatite- gabbro, anorthosite- gabbro, amphibole- pyroxenite, apatite-pyroxenite with predominant granular texture and cumulate characteristics. The associated main mineral assemblage composed of cumulate predominantly clino-pyroxene, Fe-Ti oxides, calcic plagioclase, amphibole, apatite, as well as minor olivine. The intrusion formed from mafic magma and differentiated from tholeiitic to weakly calc-alkaline affinity. Spider diagrams of the analyzed samples were normalized to the standard values of chondrite and primitive mantle. REE– normalized diagrams are characterized by LILEs enrichment and HFSEs depletion and mild negative REEs trend. Different tectonic setting discriminative diagrams and elemental ratios are indication of a subduction related affinity. The parental magma could be generated by melting of mantle peridotites (lithospheric mantle) which previously affected by subduction related fluids. The results of this research is consistent with the previous models which considered the Early Cambrian magmatism in Post-e-Badam block related to the subduction of Proto- Tethys oceanic crust beneath the Central Iran in the north of Gondwana land.

The Lake Siah magnetite ± apatite deposit is situated in the northeastern of Bafq and Central Iran tectonic zone. The host rock of deposit is composed from lower Cambrian volcano-sedimentary sequence that has exposed as caldera complex. The iron mineralization is as massive ore and includes magnetite and hematite which form with apatite, quartz and calcite gangue minerals. Based on fluid inclusions petrography in quartz and apatite, at least five types of fluid inclusions are recognized including, multi-phase solid bearing (L+V+S1+S2), three phase solid bearing (L+V+S), liquid-rich two phase (L+V), vapor-rich two phase (V+L) and monophase vapor (V(. The three phase fluid inclusions are the most abundant of fluid inclusions type and indicate homogenization temperature between 123 to 530°C (avg. 344°C) and salinity content 30 to 58 wt% NaCl equiv. (avg. 40.60 wt% NaCl equiv.). Three phase fluid inclusions in the apatite are characterized by homogenization temperature between 175 to 420°C (avg. 385°C) and salinity between 34 to 53 wt% NaCl equiv. (avg. 41.58 wt% NaCl equiv.). Calculated pressure on the basis of microthermometric measurements on fluid inclusions in the H2O-NaCl system is calculated between 10 to 500 bar which is corresponding with depth between 0.5 to 1.5 km. The values δ18O of fluid in equilibrium with quartz is 7.5 to 11 ‰ which indicated magmatic waters origin. According to wide range of fluid inclusion homogenization temperature and salinity accompanied with positive correlation between salinity and homogenization temperature of fluid inclusions, mixing of hot and high salinity fluid with cold and low salinity water (similar to meteoric waters) is main factor for occurrence of the Lake Siah deposit.

Choghart iron deposit is located in central Iran and 12 km north east of Bafgh, 130 km southeast of Yazd city. The dominant host rock in this area is the complex of intermediate-acidic igneous infiltrations and Mafic dykes, which have been highly altered in some parts and are known as metasomatitis. These igneous rocks have been transformed in some places to the extent of the green schist facies. Magnetite is the most abundant oxidizing ore in the region, in layered, massive and diffuse forms in the host rock of Choghart deposit. The main ore mineralization of the deposit occurred in the late Precambrian formations of high-grade (magnetite + apatite + amphibole). The data from the study of fluid transitions in monolithic apatite with magnetite shows that the Changar iron mass canal is in the range of 370 to 385 ° C. The highest salinity rate was found to be 20-39% by weight, equivalent to salt. Field evidence and micro-measurements of fluid transitions in Chaghart mineral deposit apatite show that ore-bearing fluid is very similar to that of magmatic-hydrothermal deposits of gold-copper-iron oxide (IOCG).

Ore deposits of the Bafq-Saghand metallogenic province (IRAN) with Proterozoic age represent that they belong to classic genetic model for hydrothermal iron oxide (Cu, Au, U, REE) deposits, which is widely referred to as iron oxide coppergold (IOCG) and iron oxide-apatite (IOA) deposits (Samani, 1988; Daliran et al., 2007; 2010; Jami et al., 2007; Nabatian et al., 2015; Rajabi et al., 2015). According to the structural zone of Iran, the Bafq mining district is part of Central Iran and therein Kashmar-Kerman tectonic zone (Zarigan-Chahmir basin), and Lake Siah deposit occurs in Early Cambrian Volcano-Sedimentary Sequence (ECVSS). According to Förster et al. (1988) and Torab (2008), the Bafq mining district is composed of a huge volcanic suite in which sedimentary structures, fossils, and even glassy volcanics a surprisingly are well preserved. Calderas are important features in all volcanic environments and are commonly the sites of geothermal activity and mineralization (Cole et al., 2005). The Lake Siah iron±apatite deposit is located between Kusk and Esfordi deposits and 40 km northeastern Bafq (31°46´47 N and 55°42´56 E). A total of 50 samples were collected from the Lake Siah mine district. Ten samples of least-altered igneous rocks were analyzed for major, trace and rare earth elements by inductively coupled plasma spectrometry (ICP-MS), and X-ray fluorescence (XRF) at the Acme laboratory (Canada). The detection limit for major oxide analysis is 0.01%. Electron microprobe analyses (EMPA) and backscattered electron (BSE) images of minerals were obtained using a Cameca SX100 electron microprobe at the Iran Mineral Process and Research Center (IMPRC). An accelerating voltage of 15 to 25 kV and beam current of 20 mA was used for all analyses. The Lake Siah deposit with a covering area of about 5 km2 is located in the Central Iran Block and therein Kashmar-Kerman tectonic zone (Zarigan-Chahmir basin). The Nb/Y versus Zr/TiO2 diagram shows a typical trend from rhyolite and evolving to andesite/trachyandesite compositions, with few data plotting in the dacite/rhyodacitic rocks. Most of the igneous rocks plot within the high-potassic calcalkaline to shoshonitic fields in the Th/Yb versus Ta/Yb diagram (Pearce, 1983). All studied rocks show similar incompatible trace element patterns with an enrichment of large ion lithophile elements (LILE: K, Rb, Ba, Th) and depletion of high field strength elements (HFSE: Nb and Ti), which are typical features of magmas from convergent margin tectonic settings. The Lake Siah deposit is composed of the hematite and magnetite as major minerals and apatite, goethite, pyrite and chalcopyrite as minor minerals. The deposit is controlled by NE-SW normal faults and occurs within early Cambrian trachyte, trachyandesite and rhyolite of the Lake Siah caldera. Intermediate argillic, sodic (albitic), silisic, potassiccalcic, hydrolytic (acidic), and sodic-calcic (Fe) alterations occur near the ore deposit. Lipman (1992) identifies a number of stages in the development of a caldera which includes: 1) pre-collapse volcanism, 2) caldera subsidence, 3) post-collapse magmatism and resurgence, and 4) hydrothermal activity and mineralization. Flow of dacite and andesite into the shallow magmatic system is facilitated by regional fault systems which provide pathways for magma ascent. Dacite and remobilized rhyolite rise buoyantly to form domes by collapse of the chamber roof and producing surface resurgent uplift. The resurgent deformation caused by magma ascent fractures the chamber roof, increasing its structural permeability and allowing rhyolite magmas to intrude and/or cause eruption. Explosive eruption of high viscosity magma is the cause of creating fractures and breccia in the host rocks and facilitated percolation Fe-P bearing magmatic fluids.

At present, about 36% of the land surface is covered by arid and semi-arid areas, with 19% of these levels completely dry and no plant life. In Iran, between one third and one-fourth of Iran's dry surfaces are covered with Sand and Sand Dunes. The arid and semi-arid conditions of Iran have caused about 80 million hectares of Iran to be covered by desert areas, sand dunes and insignificant vegetation areas. Therefore, the sand dunes are as one of the geomorphologic types dominate the, which is called Erg in a region of collection of sand dunes. From the shape, sand dunes can be divided and studied from different perspectives. For example, sand dune morphology may consider in transverse, linear, Compound and complex sand dunes or star, Barchan and crescent sand dune morphology stellate or pyramid sandy hills. In general, the first studies on sand dunes relate to the Bagnold study in 1941, which shows that influence of the wind regime on the sand particles diameter and sand dune morphology. He believed that the similarity between morphology and the behavior of sand dune morphology can be used different models to study the sand dunes and Erg morphology. In this research, by studying the wind regime of Sadegh Abad area and studying the effect of wind direction, Different conditions for the formation of various types of sand dunes morphology Influenced by wind, have been discovered. Daranjir Graben is located in the geographical coordinate’s 55 00 15 to 55 49 30 E, longitude, and 32 34 50 to 31 08 20 N, latitude along the southeast of Yazd, which extends from Kharandagh to Bafq. The Erg of Sadegh Abad is located in Daranjir Playa. Because of the role that wind characteristics in eroding area, Study of sand dunes requires to examine of wind characteristics of an area. Also, because of the dominant morphology of the sand dunes in ergs are dependent on wind direction variations, wind directional studies methods are necessary to investigate the morphology of the sand dunes. The easiest method to study wind regime in a region is to draw wind rose using wind speeds and wind direction data. Wind rose can be plotted monthly, seasonally, and yearly. Therefore, in this study, wind speed and wind direction data of Bafq weather station during a 20 year period (1997-2017) were used in Wrplot software to determine the wind direction in Sadegh Abad. In addition to the prevailing wind direction and drift potential sand, Sand rose was drawn up by Sand Rose Graph software. Considering the type of morphology of the sand dunes depends on the degree of stability and the wind direction, in order recognize wind regime at a meteorological station. In this condition may change the direction of the wind in a month or season and changing the morphology of the sand dunes over time. Therefore, in the first stage, seasonal and annual wind rose was used to determine the direction of the dominant wind in different seasons. In the next stage, with the fact that the unidirectional index (UDI) slightly changing, with the annual, seasonal and monthly calculated sand rose and another sand movement indexes in the synoptic station Bafq. The Bafq station annual wind rose shows that the direction of the wind dominates is northwest. However, winds could be seen in other directions. The annual sand rose at the summer and spring indicate that the direction of the predominant sand transport is some direction with the dominant wind direction. But, the autumn and winter sand rose show the opposite of this and can be seen the dominant winds of the sand carrier were in a direction perpendicular to the direction of the prevailing north-west winds. In addition to determining the direction of the wind, another factor that plays a more important role in morphological changes and the sand dune dominant shape in an Erg, is the UDI index, or the rate of wind stability at different time periods. In order to determine the UDI value, firstly, sand indicators such as DP and RDP should be calculated and, based on the RDP / DP ratio, calculate the UDI value. The UDI was calculated at an annual rate about 0.24 at the bafq weather station at the Bafq station. In the spring, the homogeneity index of winds has a condition that is approximately equal to a ratio of 0 and 1 (UDI = 0.51) so that in the spring, and to some extent in the winter, there is a prevailing condition that, like the summer season, one can see stability in the winds and the presence of relatively one-side winds, and not like the fall of the year saw different winds toward the Sadeq Abad. The morphology of the Sand dunes is dependent on the region's wind regime, especially wind direction and its sustainability. In the monthly review of the change in RDD, it is evident that the maximum slope of wind change is in the fall season and between two months of October and November, about 90 degrees. This sudden change of wind direction from the southwest in November has had an important role in changing the morphology of the barchan and Crescent sand dunes to star sand dunes. Therefore, by examining the Bafq's wind regime at different time periods, it can be stated that the best conditions for the development of the Star sand dunes are provided in the winter and mid-spring While summer with the highest unidirectional index (UDI = 0.74) and autumn with the lowest unidirectional index (UDI = 0.19) respectively, are suitable for the development of barchan and star sand dunes in the erg of sadegh abad.

The studied area is located at the 30 km northeast of the Bafq city and near the Esphordi phosphate mine. This area composed of Rizu Series rock sequence with Upper Precambrian- Lower Cambrian age. The mentioned sequence has been intruded by some seyenitic and gabbroic intrusions. Petrographical studies indicate that syenites contain hetero- granular, perthite and checkerboard textures and composed of alkali- feldspar (orthoclase), plagioclase, amphibole, pyroxene and biotite. Gabbros contain hetero- granular, and inter- granular textures, and composed of plagioclase, clinopyroxene, amphibole and biotite. Geochemical studies demonstrate that syenites and gabbros have high- K to shoshonitic alkaline nature. Based on the spider diagrams, the two mentioned intrusion have similar trend which can be indicative for their genetic relation. These diagrams indicate enriched LILEs along with negative anomalies of HFSEs. The chondrite normalized REE patterns demonstrate LREEs rich pattern with high ratio of LREE/HREE. The mentioned trends along with positive and negative anomalies of those elements probably are related to lower partial melting degrees of metasomatized mantle along with crustal contamination of this magma. Based on geochemical studies and using the discrimination tectonic setting diagrams, it seems that the studied intrusions were formed at the active continental margins toward post- collisional setting.

The Gazestan magnetite–apatite deposit is located 78 km east of Bafq, in the Bafq-Poshtebadam subzone of the Central Iran structural zone. The rock units in the area belong to the Rizou series and consist of carbonate rocks, shale, tuff, sandstone and volcanic rocks. Intrusive rocks in the form of stock and dyke crop out as granodiorite and granite in various places. Trachytic and dacitic rocks in the area are green due to chloritic alteration and host iron and phosphate mineralization. The main alteration types are chloritic and argillic, while sericitic, potassic, and silicic alterations as well as tourmalinization and epidotization are also found in the rock units. Five forms of mineralization are distinguished in the Gazestan deposit, including massive iron ore with minor apatite, apatite-magnetite ore, irregular vein-veinlets (stockwork) in the brecciated green rock and disseminated and monomineralic massive apatite veins. Fluid inclusion studies were conducted on the apatites of two stages. According to these studies, temperature and salinity values in the stage-I apatite are higher than those in stage-II apatite. Lower salinity values in the stage-II apatite could be due to contamination of magmatic fluids with meteoric waters during later stages of mineralization. Oxygen, hydrogen and carbon stable isotope composition of magnetite, quartz, apatite and calcite; and calculation of oxygen isotope composition in the fluid equilibrated with the oxide minerals suggest mixing the magmatic fluids with basin brines in mineralization of the Gazestan deposit.

The Gazestan iron oxide-apatite deposit, is locted 78 km east of Bafq at the Posht-e- Badam- Bafq block. Different kinds of lower Cambrian volcanic and subvolcanic rocks ranging from basic to felsic, outcrop in Gazestan area. Felsic volcanic rocks mainly are associated with orogenic phase and considered as an arc magmatism. In Gazestan deposit, host rocks display extensive alteration that can be classified into six groups including Sodic-calcic, potassic, sericitic, carbonates, silicic, chlorite ± actinolite ± epidote and tourmaline alterations. Chlorite ± actinolite ± epidote alteration is well developed throughout the Gazestan deposit.The ore body is mainly magnetite-apatite with less sulfides (Pyrite-Chalcopyrite) and REE minerals (allanite-monazite) which occur as breccia, banded, massive, stockwork and vein in altered volcanic rocks. Three generations of apatite are recognized which the second generation is usually enriched in REE minerals (monazite). The homogenization temperature of apatite (III) was calculated between 130-200 °C. The REE pattern of apatites show strong LREE enrichment with negative Eu and HREE anomaly. Magmatic fluids with high amounts of P, Fe and REE are responsible for the ore formation at the first stages. At the final stage of mineralization, meteoric (marine) waters mixed with the magmatic fluids, causing decrease in temperature and precipitation of late apatite and gangue minerals (calcite and quartz). The Gazestan deposit share many similarities with the Kiruna-type deposits (one of the subgroup of IOCG deposits).

Evaluating the environmental effects is one of the appropriate ways to achieve the sustainable development that can be considered as a planning tool for managers and programmers. The environmental impacts of Bafgh Anomaly Iron ore have been studied. In this regard, the most important environmental and economical-social factors that are influenced by project were identified by preparing the checklist from experts and proficient’s opinions. Subsequently, based on the Pastakia matrix method, the environmental impact assessment of project was carried out in both construction and exploitation steps. Results show that 2 positive medium effects, 1 positive low effect, 4 positive negligible effects, 7 negative negligible effects, 2 negative low effects and 3 negative medium effects are observed in environments in structural step, while 2 positive medium effects, 2 positive low effects, 3 positive negligible effects, 5 negative negligible effects, 2 negative low effects and 3 negative medium effects exist in exploitation step. Also, the environmental management and monitoring was prepared for all divisions, so that, in physical division, the air, soil and sound parameters should be continuously measured, in biological division, diversity, density, regeneration and migration of and fauna and flora should be controlled seasonally, and also the leakage and dispersion of sewages and wastes and dusts should be continuously monitored. About natural events, crisis management and risk evaluation should be done seasonally. Also, Public contribution and attaining satisfaction of society and their continuous notification and increasing the environmental knowledge of staff should be performed.

The Kharengun area is located in the Yazd province, Central Iran, 130 km east of Yazd city and 65 km northeast of Bafq city. Mineralization in Kharengun area occurred within calcic and dolomitic units of the Rizou Formation (equivalent to Soltaniyeh Formation) of upper Precambrian- lower Cambrian age. The ore minerals of this deposit includes smithsonite and hemimorphite, that is stratabound and formed epigenetically along layers and laminations of carbonate host rocks. The maximum grade of zinc in samples taken from the study area exceeds 36% and geochemical studies indicate significant absence of Pb along with Zn in this area. Therefore, the Kharengun mineralization is a monomineral Zn zone.The fluid inclusion microthermometry investments explain the role of meteoric waters in generation of this deposit. The homogenization temperatures and salinity of the inclusions show the similarity between these fluids and the solutions responsiblefor the development of epithermal deposits.The Zn mineralization present in this zone belongs to the nonsulfide supergene deposit class, and a mixture of wallrock replacement and direct replacement subclasses.

In order to study the paleoecology of the Aptian gastropods, the Bafgh section with 380 meters thickness, in East of Yazd were studied in detail. In this region, a variety of different fossil groups, including macrofossils (gastropods, ammonites and echinoids) and microfossils (foraminifers and ostracods) are present and suggest an Aptian age for this section. 11 genus and species of gastropods are reported for the first time from this section. The microfossils and macrofossils assemblage all show a shallow environment with a suitable conditions for the time of sedimentation in the study area.

The Gazestan magnetite–apatite deposit is situated 78 km east of Bafq. The Gazestan deposit is located in Bafq-Poshtebadam subzone of Central Iran structural zone. The rock units in the area belong to the Rizu series and consist of carbonate rocks, shale, tuff, sandstone and volcanics. In addition to sedimentary and volcanic rocks, intrusive rocks in the form of stock and dyke outcrop as diorite gabbro, gabbro, diabase, quartz-monzonite and granite in various places. The green rocks with acidic to intermediate composition (trachyte and dacite demonstrate green color due to alteration) host iron and phosphate mineralization which in some localities, show subvolcanic facies. The alteration is more obvious in the volcanic rocks and includes chloritization, argillic, silicification, and also formation of mafic minerals such as epidote, tremolite and actinolite. The host rocks are strongly altered. Mineralization at the Gazestan deposit comprises a combination of iron oxides and apatite with various ratios accompanied by quartz and calcite, observed in different forms mainly within the trachytic-dacitic rocks and a small proportion in the rhyolites. Five forms of mineralization are distinguished in the area including massive iron ore with minor apatite, apatite-magnetite ore, irregular vein-veinlets (stockwork) in the brecciated green rocks, disseminated, and pure massive apatite veins. The host rocks in the Gazestan area plot on calc-alkaline field. Comparison of the most important characteristics of the Gazestan deposit (including tectonic setting, host rock, mineralogy, alteration, structure and texture) with those of various types of mineralization in the world suggest that the deposit is quite similar to the iron oxide - apatite deposits.

The Esfordi magnetite-apatite ore deposit is located in 35 Km northeast of Bafq city in Central Iran. Bafq is an important mining district which hosts more than 45 iron deposits and a few Zn-Pb massive sulfides, Mn and U deposits. The district is restricted by two main strike-slip faults of Kuhbanan to the east and Posht e Bdam to the west. The Esfordi ores occur in an Upper Precambrian-Cambrian volcano-sedimentary complex composed of acidic tuff, carbonates, shale, and sandstone. This complex intruded by granitic rocks and basic dykes and affected by regional and contact metamorphism and hydrothermal alteration. The Esfordi magnetite-apatite ores occur on top of the acidic tuff which is near to a carbonate layer. The Esfordi deposit is the most rare-earth elements (REE)-rich and most P-rich member of the iron deposits in the Bafq district. The main minerals in the Esfordi mine are Iron oxides, apatite, actinolite, diopside, talc, andradite, feldspars, quartz and carbonates. The REE minerals are closely related to apatite and were mainly formed in or around apatite grains and within veins and veinlets. This paper identifies the REE minerals and presents preliminary information on mineral composition and geological and mineralogical features of the deposit. The REE-bearing minerals are mainly of phosphate, fluorocarbonate and silicate groups. The REE minerals are highly enriched in light REE such as Ce, La, Nd and Pr. Apatite contains a few percent REE in its composition. However, the main part of REE may be from apatite as it is the main mineral of the deposit and apatite-rich horizons contain high-grade REE ore. The metasomatic assemblage, one head crystals of apatite and many mineralized veins and veinlets indicate that hydrothermal process were definitely active in the Esfordi deposit at later stages.