فصلنامه زمین شناسی اقتصادی
سال ششم شماره 2 (پیاپی 11، پاییز و زمستان 1393)

The Mn mineralization occurs in the northeastern segment of the Sabzevar zone (SZ)، north of the Central Iranian Microcontinent (CIM). This Zone (SZ) is located between the CIM fragmentation in the south and the Kopeh dagh sedimentary sequence in the north. The ore deposits of the northeastern segment of the Sabzevar zone can be divided into three groups، each with different metal association and spatial distribution and each related to a major geodynamic event. The first mineralization with associated Ordovician host rock is characterized by Taknar polymetallic (Fe-rich) massive sulfide deposit. The Cretaceous mineralization consists of Cr deposits associated with serpentinized peridotites، Cyprus type VMS، Mn deposit in pillow lava، volcano-sedimentary hosted Besshi type VMS and Mn deposit. Paleogene mineralization in eastern segment of the Sabzevar zone began with porphyry deposits، Cu Red Bed mineralization occurs in the Paleogene sandy red marl.

A field study and sampling was performed during the autumn of 2012. To assess the geochemical characteristics of 48 systematic samples (least fractured and altered) of ore-bearing layers and host rocks were collected from the deposit for polished thin section examination. In order to correctly characterize their chemical compositions، 15 least-altered and fractured samples were chosen for major elements analysis.

The Late Cretaceous volcano-sedimentary sequence in south-southwest of Sabzevar hosts numerous manganese mineralization. The sequence based on the stratigraphic position، age and composition of the rocks، can be divided into two lower and upper parts. The lower part or K2tv unit mainly formed from marine sediments interbedded with volcanic rocks. The sedimentary rocks of this part include silicified tuff، chert، shale and sandstone، and the volcanic rocks involve pyroclastic rocks of various composition، rhyolite، dacite and andesitic lava. The upper part or LMV unit comprised of limestone، marl and volcanic rocks، overlies concordantly on the lower part (K2tv). The manganese mineralization within the host volcano-sedimentary sequence، based on stratigraphic position، relative age and type of host rocks involved the two horizons: the first horizon (Mn Ia، Ib) consisting of Benesbourd (Masoudi، 2008)، Nudeh (Nasrolahi et al.، 2012)، Homaie (Nasiri et al.، 2010)، Goft and Manganese Gostar Khavar Zamin deposits، occurred in the lower part of the sequence (K2tv unit) and is hosted by red tuffs. The second horizon (Mn II) comprising of Zakeri (Taghizadeh et al.، 2012)، Cheshmeh Safeid، Mohammad Abad Oryan and Chah Setareh deposits، is hosted by marly-carbonate tuffs and locates within the upper part of the sequence (LMV unit) (Maghfouri، 2012). Geometry and shape of the ore bodies in various deposits are as stratiform، layered، parallel and concordant with layering of the host rocks. Textures of the ores include massive، lenticular، banded، laminated and disseminated. Mineralogy of the ores in the two ore horizons is simple and similar and is dominated by pyrolusite، psilomelane and braunite. Gangue minerals are predominantly the host rock-forming minerals including quartz، chlorite and feldspar.

Geochemical data، structures and textures، stratigraphic position and lithologic characteristics of the host rocks represent that manganese reserves in south-southwest Sabzevar were formed as sedimentary-exhalative.

The area reviewed and studied in this paper is located 5 km southeast of Sarbisheh city at eastern border of the Lut block (Jung et al.، 1983; Karimpour et al.، 2011; Richards et al.، 2012) in eastern Iran between 59° 47′ and 59° 53′ E longitude and 32°30′ and 32°34′ N latitude. The magmatic activity in the Lut block began in middle Jurassic (165-162 Ma) and reached its peak in Tertiary (Jung et al.، 1983). Volcanic and subvolcanic rocks of Tertiary age cover over half of Lut block with up to 2000 m thickness and formed due to subduction prior to the collision of the Arabian and Asian plates (Camp and Griffis، 1982; Tirrul et al.، 1983; Berberianet et al.، 1982). Most of magmatic activity in the Lut block formed in middle Eocene (Karimpour et al.، 2011) The andesitic volcanics were erupted together with the dacites and rhyodacites during a time interval of some 50 Ma from early Cretaceous to early Neogene. It can be assumed that the intensity of the volcanic activity was varying significantly during this time span (Jung et al.، 1983). Tertiary volcanic rocks (Eocene-Oligocene to Pliocene) with intermediate composition associated with pyroclastic rocks cropped out in eastern parts of Salmabad village، southeast of Sarbisheh. The main purpose of this paper is better understand the tectono-magmatic setting of the Tertiary volcanic rocks in southeast of Sarbisheh، eastern Iran based on geochemical characteristics.

Eleven samples were analyzed for major elements by inductively coupled plasma (ICP) technologies and trace elements were analyzed using inductively coupled plasma mass spectrometry (ICP-MS)، following a lithium metaborate/tetraborate fusion and nitric acid total digestion، at the SGS Laboratories، Toronto، Canada.

In the Salmabad area، Tertiary volcanic rocks with mainly intermediate (andesitic) composition are exposed associated with pyroclastic deposits such as tuff، breccia and agglomerate. Extrusive rocks include andesite (pyroxene andesite) and basaltic andesite. Zoning، sieve texture and embayment of plagioclase phenocrysts and existence of reaction rims around pyroxenes are evidences for disequilibrium conditions during magma crystallization. These rocks have medium to high-K calc-alkaline nature and show enrichment in LILE (except for Ba) and depletion of HFSE. The Salmabad area lavas have 102-155 ppm total REE and display coherent REE patterns characterized by enrichment in LREEs relative to HREEs ((La/Yb) N=7. 35-9. 71; (Ce/Yb) N=5. 43-6. 81))، nearly flat HREEs ((Tb/Yb) N=1. 05-1. 40) and weak negative Eu anomalies (average Eu/Eu*=0. 78). Geochemical characteristics of the Salmabad volcanic rocks such as enrichment in LREEs relative to HREEs in association with enrichment in LILE and negative anomalies of Nb، Ti and P show their relation to subduction zone. The range of Mg# is 45. 1-57. 1 for the Salmabad andesites and 69. 8 in basaltic andesite indicating the involvement of mantle components. The isotopic compositions (87Sr/86Sr) i=0. 7045 and εNd (t) =3. 1 for the Salmabad andesites point to a mantle origin.

Orogenic magmas are defined geochemically as showing diagnostic Nb-Ta trough and enrichment in large ion lithophile elements (LILE) such as Th، Pb، Sr and K in primitive mantle normalized trace element variation diagrams (Kuscu and Geneli، 2010). The origin of this kind of geochemical signature is commonly interpreted as subduction-related setting (Gill، 2010)، in sources that had undergone mantle wedge metasomatism (Seghedi et al.، 2001) or crustal contamination of mantle-derived magmas (Harangi et al.، 2007). The andesitic magma in Salmabad area displays an orogenic signature، i. e.، enrichment in LILE and Th، and relative depletion in Nb، Ti and P. The dominance of positive εNd (t) values (3. 1) for the studied rocks indicate a mantle origin. High values of Sr، Th and U in these rocks can be related to crustal contamination. Thus، the orogenic signature of these rocks is attributed to the mantle source، presumably metasomatized by the Sistan ocean subduction. The trace element features are consistent with the roles played by subducted sediments and fluid released from the subducted slab in magma genesis.

The Zafar-abad iron ore deposit، situated in the NW part of Divandarreh (lat. 36°01''14 «and long. 46°58''22»). The ore body is located on the northern margin of the Sanandaj-Sirjan igneous metamorphic zone. The Zafar-abad Fe-skarn deposit is one of the important، medium- size mineral deposits in western Iran. REE patterns of skarn magnetite were among others studied in Skarn deposit by (Taylor، 1979) Hydrothermal alteration and fluid-rock interaction significantly affect total contents of REE and their patterns in fluids. Moreover، fractionation of REE by chemical complication، adsorption effects and redox reactions are characteristic processes determining REE behavior during crystallization. Stable isotope data for oxygen and sulfur have been widely used with great success to trace the origin and evolution history of paleo-hydrothermal fluids of meteoric، magmatic، and metamorphic. The present study investigates REE and stable Isotope geochemistry of magnetite and pyrite in Zafar-abad deposit and temperature of trapped fluid inclusions based on geothermometry analysis. In order to study the major، trace and REE compositions of Zafar-abad magnetite، twelve samples were collected from surface of ore exposures. The emphasis during sampling was on ores with primary textures. The Zafar-abad district is situated in Mesozoic and Cenozoic sedimentary، meta-sedimentary and meta-igneous rocks in Sanandaj-Sirjan igneous metamorphic zone. Sedimentary sequences dominantly composed of calcareous and conglomerate rocks. Various meta-sedimentary rocks are intercalated with the sedimentary rocks، and comprise biotite and muscovite-rich schist، calc-schist، calc-silicate rock. Several distinct ductile tectonic fabrics have been identified around the Zafar-abad deposit. The main ore body at Zafar-abad is in the form of a roughly horizontal، discordant، lens to tabular-shaped body plunging 10° NW، where it appears to interfinger with meta-sedimentary and fragmental wall-rock. The thickness of the ore body is 25 to 35 m with 40 m wide and around 130 m in elongate. The chondrite normalized REE distribution pattern of Zafar-abad magnetite shows V shape. The analyzed samples display similar patterns. The average (La/Yb) cn ratio of 6. 8 indicates a high degree of fractionation. The fractionation is more pronounced in HREE part of diagram، where the average (Gd/Yb) cn ratio is 1. 07، whereas the average (La/Sm) cn ratio in the LREE part of the diagram is only 5. 9. This indicates that the REE content in Zafar-abad magnetite is not affected by hydrothermal alteration. The ΣREE content varies between 2. 09 and 15. 02 ppm with an average of 8. 4 ppm. These REE values are equal to those reported for the type of Skarn- type iron deposits (Bowman et al.، 1985). Other features include pronounced negative Eu and Ce and positive Pr and Gd anomalies. Six purified magnetite samples used for Isotope Studies and δ18O values are measured in them. The units of results are permil (‰) relative to SMOW for oxygen. The δ18O values content varies between -5. 93 and -0. 28 ‰ with an average of -2. 26 ‰. Considering that the magnetites formed at two stages (Meinert، 1995)، the first one about 370 °C، and the second one about 240°C which is a reasonable guess bearing in mind that they are associated with intrusive and extrusive granitoids، then the fluid from which they formed، would yield δ18O values that range from 4. 1 to 8. 1 ‰ which will fall in the boundary of magmatic water box and hence provide further support for a mixed magmatic and meteoric origins of Zafar-abad magnetite deposit. In the Zafar-abad deposit، sulfur isotope composition was studied on six pyrite samples. The δ34S values for this mineral in Zafar-abad vary from +1. 2 to +1. 9 ‰، with an average value of +1. 61‰. Zafar-abad isotopic temperatures have been determined from the δ34S values in pyrite. This temperature range is from 204 to 350°C. Fluid inclusion studies illustrate the presence of two different types of hydrothermal fluids at Zafar-abad iron deposit. The earliest hydrothermal fluid with high salinity (11 to 49 wt % NaCl equiv) and high temperature (> 320°C) had a magmatic origin. This magmatic fluid moved upward to shallower levels، and its temperature subsequently decreased. The meteoric water circulated in the peripheral parts of magnetic lens and layers this water moved inside the earth and after interaction with magmatic water، the magmatic fluid gradient decreased and then produced a mixture of magmatic and meteoric fluid with salinity of 15 to 25 wt % NaCl equiv. Geochemistry and REE studies indicate that the iron has magmatic origin and the REE content in Zafar-abad magnetite is not affected by hydrothermal alteration. The ΣREE content indicate Skarn-type for this deposit. The δ34S values of pyrite at Zafar-abad ranging from +1. 2 to +1. 9‰ that suggest a predominant magmatic origin for sulfur. The δ18O values of magnetite at Zafar-abad ranging from between -5. 93 and -0. 28 ‰ with an average of -2. 26‰ that suggest the magnetites formed at two stages. Fluid inclusion studies show the presence of two hydrothermal fluids at Zafar-abad deposit. The fluid 1، originated from high temperature and pressure magma. The fluid 2، is a mixture of magmatic fluid with meteoric water which has low temperature and salinity، these fluids were responsible for genesis of ore body.

Arefi quartz-bearing conglomerate (Middle Jurassic) is situated within Binalud structural zone. The unit is trending NW-SE located 25 km south of Mashhad. More than 97% of the pebbles are quartz as mono-crystalline، poly-crystalline، and minor fragments of chert، quartzite، and mica schist. Less that 3% of the remaining minerals are feldspar، mica، chlorite، hornblende، tourmaline، zircon، sphene، and opaque minerals. The cement is mainly silica. Hashemi (Hashemi، 2004) suggested this unit is orthoquartzitic polymictic conglomerate. In this study، we carried out detailed mineralogical studies، geochemical analyses for SiO2 and troublesome elements، determination of quartz pebbles source using geological observations and fluid inclusion microthermometry، and industrial application studies with new insight for porcelain and ceramic factories as the nearest silica-rich reserve to Mashhad.

1. Preparing geologic map in 1:10000 scale in the Arefi area. 2. Petrographic study of 65 samples from the quartz-bearing conglomerate unit. 3. Major elements such as SiO2، TFeO، TiO2، and CaO were analyzed at the Maghsoud Porcelain Factories Group، using a Philips PW1480 X-ray spectrometer. 4. Ore dressing analyses in Danesh Faravaran Engineering Company. 5. Fluid-inclusion studies in 4 samples doubly-polished wafers of quartz crystals were studied using standard techniques (Roedder، 1984) and Linkam THM 600 heating-freezing stage (from –190 to 600ºC) mounted on a Olympus TH4–200 microscope stage at Ferdowsi University of Mashhad، Iran. Salinities and density of fluid inclusions were calculated using the Microsoft Excel spreadsheet HOKIEFLINCS-H2O-NACL (Steele-MacInnis et al.، 2012; Lecumberri-Sanchez et al.، 2012)

Fluid Inclusion studies of both mono- and poly- crystalline quartz revealed that the inclusions consist of three phases (LVS) with NaCl crystals. Homogenization temperature is between 484 and more than 600ºC with average 559ºC and the salinity is between 49. 6 and 72. 1 wt% NaCl with average 61. 2 wt% NaCl. These data indicate a magmatic origin according to Kesler (Kesler، 2005) diagram. Homogenization temperature of two phases (LV) inclusions in the metamorphosed quartz is between 287 and 365ºC with average 318ºC. The main source of quartz pebbles is quartz veins formed within the top of pegmatite-granite (upper Triassic) of Khajeh-Morad area and quartz veins formed due to regional metamorphism. Based on chemical analysis of 93 samples which were taken from the surface (channel method) and power drilling، the SiO2 content is more than 98%، TFeO is less than 0. 42% and TiO2 is less than 0. 16%. The proved ore reserve is more than 50 million tonnes. Using dry magnetic method، the TFeO became less that 0. 03% and TiO2 less than 0. 02%. Arefi silica deposit is a first-class reserve and can be used in different types of ceramic.

Agates are presumed as a kind of precious stone that could be formed in magmatic، metamorphic and even sedimentary environment. Mechanism for agate formation is not clear and is produced in laboratories. Some hot springs and geothermal activity or white chimneys in the ocean floor، have some deposits like chalcedony but never produce agate. Agate formation temperature varies between 50 and 400 °C (Hopkinson et al.، 1998). Following field studies، 6 unaltered samples from the parent rock and silicic zone were collected. Analytical data were obtained by X-Ray Fluorescence (XRF) for major elements and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for selected trace elements at the School of Earth and Environmental Science، Washington State University (WSU)، USA. The stable isotope analysis was performed at the Department of Ecology and Evolutionary Biology، Oregon University، USA. Silica samples mineralogy was determined by X-Ray Diffraction (XRD)، using Rigaku Ultimate III advance powder equipped; operating at 50 kV and 50 mA، using a Ni filtered Cu Kα radiation. Tashtab Mountain is a part of the Central Iranian micro-continent which belongs to Cenozoic. The study area is located in northeastern Isfahan province and is in the Yazd block surrounded by three major faults as a graben، consisting of Doruneh fault in the north، Torkmani-Ordib in the south، and Posht-e-Badam fault on the right side. The study area is dominated by Eocene volcanic rocks ranging from alkali basalt، trachybasalt، trachy-andesite to trachyte with minor subvolcanic and plutonic rocks. The Darreh Anjir conglomerate at the base and the Qom Formation at the top، consisting mostly of sandstone and limestone، enclosed the Eocene volcanics. Khur bentonite horizon forms as a result of alteration of these volcanic rocks. In an overall field observation، the volcanic parent rock appears as short hills surrounded by bentonite deposits، which formed as a result of alteration of volcanic rocks. Outcrops of silicic compositions have been developed as agates، geodes، jasperoids، and siliceous veins. The volcanic rocks are plotted on the discrimination diagrams proposed by (Winchester and Floyd، 1977). The projection of the volcanic samples on the Nb/Y against Zr/TiO2 diagram shows the composition from andesite to andesite basalt. The XRD analysis revealed that assemblage of these silicic rocks composed of quartz، calcite، dolomite and hematite. These silica compounds have been mostly formed near the faults and fine joints، also some agates can show the growth during fault activities. Formation of calcite adjacent to quartz in a geode، with a serrate margin is something unusual. Silica and calcite could not be formed in the same pH condition; therefore، it seems that silicic hydrothermal fluids flow outward alternatively in an alkaline aqueous basin. Calcite macles show a temperature of below 200°C in (Burkhard، 1993). Rare earth elements in the silicic samples show a similar trend with host rock. A strong removal of all elements has occurred. HREEs removal happens more than LREEs. The relation between REEs in the silicic samples and host rock happens as a result of fluid circulation inside the host rock during and after alteration. Strontium and Zr depletion represents less than other elements. Strontium can replace the calcium carbonate compounds. Uranium is not changed and has the same amount of silica and host rock. High concentrations of some elements such as Ge، U، and B especially in agates indicate that hydrothermal fluids can play a role in the alteration of volcanic rocks، the mobilization and transport of SiO2. Cesium is enriched in the silicic samples and is one of the products of U decay. Concentration of Cs and formation of violet agates could happen due to the weak effect of radioactive elements in the region. Two silicic samples from agate and silicic vein were selected for oxygen-deuterium stable isotopic analysis. The isotopic distribution of mineral-fluid is affected by temperature changes. A variety of methods for determining the oxygen isotope distribution coefficient between quartz and fluid at different temperatures are presented. The Clayton et al. (Clayton et al.، 1972) equation was used to calculate the oxygen distribution coefficient between water and quartz. 103lnα (Qz−H2O) = (3. 38* 1010) /T2* – 2. 9Due to the lack of water in quartz structure، all deuterium could be estimated as hydrothermal fluids deuterium. Therefore، no correction is needed. Study of oxygen and deuterium stable isotopes in two samples of silica and comparing the results with normal reservoirs of silica samples، determines the type of atmospheric water. Analysis of two silicic samples and comparison with some natural reservoirs suggests that hydrothermal fluids has atmospheric source. The Khur agates formed in the cavities of Eocene volcanics with andesitic basalt composition within the Khur bentonite horizon. Field observation indicates that the Khur agates formed independent of faults and joints. According to the XRD analysis، their composition mainly consists of silica and calcite، as well as dolomite and barite in lower quantities. Trace elements and REEs in both silicic samples and andesitic host rock has same trend with large amount of depletion in the silicic samples. Mineralogical evidence suggests that Tashtab agates formed as a result of periodic eruption of low temperature hydrothermal fluids. Also، oxygen and deuterium stable isotope data resemble hydrothermal fluids with atmospheric origin.

Geological background Ophiolites have played a major role in our understanding of Earth’s processes ranging from seafloor spreading، melt evolution and magma transport in oceanic spreading centers، and hydrothermal alteration and mineralization of oceanic crust to collision tectonics، mountain building processes، and orogeny. They provide the essential structural، petrological، geochemical، and geochronological evidence to document the evolutionary history of ancient continental margins and ocean basin. Ophiolites include a peridotitic mantle sequence، generally characterized by high-temperature plastic deformation and residual chemistry، and a comagmatic crustal sequence (gabbros، diabase dikes، and submarine basalts)، weakly or not deformed. According to this interpretation، ophiolites were allochthonous with respect to their country rocks. They were assembled during a primary accretion stage at an oceanic spreading center، and later tectonically emplaced on a continental margin or island arc (Dilek، 2003). The indigenous dikes of pyroxenites and gabbros that were injected into a melting peridotite، or intrusive dikes of pyroxenite and gabbro that injected when the peridotite was fresh and well below its solidus، are discussed in different ophiolite papers. Pyroxenite formation and contact of gabbro and mantle peridotite are discussed in different articles (Dilek، 2003). When a gabbro intrude a fresh mantle peridotite could not significantly react with it، but if intrusion occurs during the serpentinization، the gabbro will change to rodingite. Geological setting: The Naein ophiolitic melanges comprise the following rock units: mantle peridotites (harzburgite، lherzolite، dunite، with associated chromitite)، gabbro، pyroxenite، sheeted and swarm dikes، massive basalts، pillow lava، plagiogranite، radiolarian chert، glaubotruncana limestone، rodingite، listvenite، and metamorphic rocks (foliated amphibolitic dike، amphibolite، skarn، banded meta-chert، and succession of schist and marble) (Davoudzadeh، 1972; Jabbari، 1997; Pirnia Naeini، 2006; Torabi، 2012; Shirdashtzadeh، 2006). In this ophiolite، the leucogabbro intrusions crosscut all other rock units. Mineralogical analyses were conducted by wavelength-dispersive EPMA (JEOL JXA-8800R) at the Cooperative Centre of Kanazawa University (Japan). The analyses were performed under an accelerating voltage of 15 kV and a beam current of 15 nA. JEOL software using ZAF corrections was employed for data reduction. Natural and synthetic minerals of known composition are used as standards. The Fe3+ content in minerals was estimated by assuming mineral stoichiometry. In the contact zone of leucogabbros and mantle peridotites of the Naein ophiolite، wehrlite and olivine clinopyroxenite are formed. Rock-forming minerals of these wehrlites are olivine (chrysolite)، clinopyroxene (diopside)، Cr-spinel، serpentine، amphibole (tremolite and tremolitic hornblende)، epidote and magnetite. Comparison of mineral chemistry of olivine، clinopyroxene and chromian spinel in wehrlites and mantle peridotites indicate that chemical composition of clinopyroxene and olivine in these rocks are different، but chemistry of Cr-spinels in harzburgite and wehrlite are nearly same. According to the resistance of Cr-spinel against the metamorphism and alteration، it can be concluded that the wehrlites in contact zone of gabbros and mantle peridotites are formed at the expense of harzburgite. Olivine and clinopyroxene of wehrlites are formed by serpentine metamorphism and interaction of serpentine and calcium of gabbro، respectively. Field study of the research area shows that the leucogabbro intrudes the harzburgite. This research shows that after the serpentinization of mantle harzburgite، the gabbro intrusions crosscut the serpentinized peridotites، and wehrlite and olivine clinopyroxenite formed in the contact zone.

High concentrations of metals are usually encountered in surface soil and vegetation in areas affected by mining activity (Liu et al.، 2006). Different distribution of elements in chemical fractions result in different bioavailability; therefore knowledge of the total content of an element in soil is not a sufficient criterion to estimate the environmental implications of trace metal presence (Maiz et al.، 2000). Sequential extraction analysis gives information on the element distribution among different phases of soil. Several schemes of sequential extraction are used for the determination of commonly distinguished metal species، which are in general: (1) easily exchangeable or water soluble; (2) specifically sorbed; e. g.، by carbonates or phosphates; (3) organically bound; (4) occluded by Fe-Mn oxides and hydroxides; and (5) structurally bound in minerals or residual (Kabata-Pendias and Mukherjee، 2007). The main objectives of this study are: (1) to describe the distribution pattern of elements in rocks and soils of the Miduk area; (2) to assess the fractionation of elements in soil and the mining impact on the mobility of trace elements; (3) to investigate the uptake of analyzed elements by selected indigenous plant species. In this study، 32 soil samples at two depths (0-5 cm and 15-20 cm)، were analyzed for total concentration of 45 elements. In order to assess the possible bioaccumulation of the elements، the roots and the overground parts of 3 plant species (Astragalus-Fabaceae، Acanthophyllum -Caryophyllaceae، Artemisia -Asteraceae) were also collected and analyzed. Enrichment factors (EFs) were calculated to assess whether the concentrations observed represent background or contaminated levels. The Tessier et al. method (Tessier et al.، 1979) was chosen for sequential extraction of 6 subsoil samples. Correlation analysis was used to examine the relationship between the analyzed elements in soil. The plant’s ability to take up chemical elements from growth media was evaluated by calculating transfer factor (TF) (Kabata-Pendias and Pendias، 2001). Topsoil samples displayed higher mean levels of Mo، Cd، Se، Fe، As، Pb، Cu and Zn compared to subsoil samples. Generally، Cu is accumulated in the upper few centimeters of the soil، but in deeper soil layers it has a tendency to be absorbed by organic compounds and oxy-hydroxides of Mn and Fe (Kabata-Pendias and Mukherjee، 2007). The total mean concentrations of Cu (201. 19 mg kg-1)، As (26. 90 mg kg-1) and Pb (83. 87 mg kg-1) are higher than those recorded for natural uncontaminated soils worldwide (Kabata-Pendias and Pendias، 2001). The strongest correlation (higher than 0. 80) is observed in samples taken from two depths for Zn and Pb، Zn and Cd، Cr and Ni، and Ni and Mg. The geochemical behavior of Pb and Zn is known to be similar in most natural processes (Reinmann and Caritat، 1998). Element concentrations in the roots and leaves of plants differ considerably between the three analyzed plant genuses. Element concentrations in Astragalus genus are higher than Artemisia and Acanthophyllum، expect for Pb and Cd، which displayed the highest concentration in Artemisia. Astragalus is the most contaminated species among the collected plants. The lowest concentration for all elements is found in the leaves of Acanthophyllum species. The results probably demonstrate the influence of the plant’s genetics on element uptake. The following decreasing order shows median transfer factor in plants with little differences between the three plant species: Cd>Mo>Cu>As>Mg>Mn>Pb>Fe>Ni>Ag>Co>Cr. The results of sequential extraction analysis showed that more than 54. 01% of extracted Cu is bound to Fe-Mn oxides fraction، followed by the organic matter and residual fractions. The hydrous oxides of Fe and Mn control Cu fixation in soil (Davies، 1997). Arsenic and chromium mostly remained in the residue of the sequential extraction process. The high Pb concentration in the residual and Fe-Mn oxides fractions indicated that the soil may be considered unpolluted by lead. Among the measured elements، soil contamination is mostly observed for Cu، Pb، and As. The soil of the study area is also significantly polluted by lead، especially in the old mining areas. The high concentrations of Mg، Se، and Cd extracted into the first three fractions of sequential extraction showed that the metals could be easily mobilized upon changes in ionic strength or decrease in pH and redox potential. Artemisia leaves are significantly contaminated by Cu. Arsenic and copper also accumulate in Astragalus leaves. The consumption of Artemisia and Astragalus leaves can constitute an exposure risk، especially for small domestic animals. Miduk inhabitants consume Artemisia leaves for treatment of digestive upsets. It is suggested to keep this area inaccessible to domestic animals and preferably to collect plants from distant areas. Obviously، systematic monitoring during mining should be instituted، and continuous environmental surveys should be performed to prevent future pollution problems.

In the east and northeast of Sanandaj in the Qorveh-Bijar-Takab axis، there are series of basaltic composition volcanoes with Quaternary age. The study area is part of the Sanandaj-Sirjan zone and is located between 47°52'' and 47°57'' E longitudes and 35°26 and ''35°30'' N latitudes. Due to the location of the volcanic cone on Pliocene clastic sediments and Quaternary travertine، the age of these volcanoes is considered to be Quaternary. The cones mostly consist of low scoria، ash، volcanic bombs، lapilli deposits and basaltic lava (Moein Vaziri and Aminsobhani، 1985). Petrological and geochemical studies have been carried out to evaluate Quaternary magmatism in the area and to determine the nature of the lithological characteristics، such as the evaluation of source rocks and magma type، degree of partial melting and the tectonic setting of Ghezel Ghaleh rocks (Moein Vaziri، 1997). Simplified geological map of the study area is characterized by ER-Mapper software. In the course of field studies in the region، 40 samples were taken، 30 thin sections were prepared and polished. XRD analyses were performed on some whole rock samples. All major، minor and trace elements were assessed by ICP-MS at Lab Weft Laboratory in Australia. Based on the classification of structural zones، the area is located in the Sanandaj-Sirjan zone، hundred kilometers away from the main Zagros thrust along the NW-SE direction. After early Cimmerian orogeny، andesitic volcanic activity took place (Moein Vaziri and Aminsobhani، 1985). A major secondary mineral in these rocks is iddingsite، formed by hydration and oxidation of the olivine (Shelley، 1993). According to SiO2 against Na2O + K2O (TAS) diagram (Irvine and Baragar، 1971) and cationic R1 and R2 diagram (De La Roche et el.، 1980)، volcanic rocks of the area indicate alkaline series. To obtain more information on the tectonic setting of these rocks، the Zr/Y-Zr diagram by Pierce (Pearce and Norry، 1979) as well as Nb/Y versus Ti/Y diagram of Pierce (Pearce and Cann، 1973)، show that alkali basalt rocks in the study area are fitted in the field of within plate basalts. To determine the genesis of rocks from melting curve of Aldanmaz and Colleagues (Aldanmaz et al.، 2006) based on changes in REE (La on Sm/Yb)، the samples show approximately 1 to 5% partial melting of garnet lherzolites. The spider diagrams indicate that the studied rocks are enriched in LREE and LILE، depleted in HFSE with no Eu anomaly، Cs، Sr، and Pb positive anomalies which are the characteristics of alkaline magmas and high concentrations of incompatible elements and alkaline elements in the lava، implying the melting of the lower part of the mantle source. Light rare earth elements، are incompatible with the primary crystallized phases such as olivine، clinopyroxene and plagioclase، consequently focused increasingly during phase crystallization and fractionation in the remaining fluid (Hirschman، 1998). Based on microscopic and geochemical data، these rocks are alkali basalt، basanite and tephrite. The rocks contain olivine، pyroxene، feldspar، and minerals such as iddingsite، opaque and secondary minerals، calcite with porphyritic texture and microlitic and glassy matrix، vesicular and some glomeroporphyritic، vitrophyric and amygdaloidal textures. Most minerals have undulose extinction which indicates mantle deformation. Geochemical data for the rocks indicate high-K alkaline characteristic of the primary magma. The spider diagrams indicate that the studied rocks are enriched in LREE and LILE، depleted in HFSE with no negative Eu anomaly، positive anomalies of Cs، Sr، Pb which are characteristics of alkaline magmas. These rocks are produced by partial melting of garnet-lherzolite rich under lithospheric mantle. Based on tectonomagmatic diagrams، they are within plate basalts and by magmatic series graphs are alkali basalts. Microscopic evidence such as disequilibrium textures in the minerals (zoned state، solution and twinning) shows a magmatic contamination in mixing volcanic mass.

Iron-apatite ore deposits well known as Kiruna iron type formed in association with calc-alkaline volcanism from Proterozoic to Tertiary (Hitzman et al.، 1992). Liquid immiscibility in an igneous system was proposed to explain the formation of the iron oxides accompanying apatite in mineralized zones (Förster and Jafarzadeh، 1994; Daliran، 1999). The mode of ore formation however، is a matter in debate. Bafq region in Central Iran is one of the greatest iron mining regions in Iran with 750 million tons of reservoir. The majority of the iron deposits contains apatite as minor mineral and underwent metamorphism-alteration in varying degrees. The mode of formation and geological setting of Esfordi iron-apatite deposit in this region with an average of 13. 9 wt% apatite are discussed using geochemical and mineralogical data along with field description.

Fifty-three samples of mineralized zones and host rocks collected from 7 cross sections were studied by conventional microscopic methods. Seven representative samples were determined by XRD at Department of Physics، Shiraz University. Fifteen and six samples were also analyzed for major and trace elements using XRF at Binaloud Co. Iran، and ICP-MS at Labwest Minerals Analysis، Australia، respectively. Microprobe analyses were carried out on apatite in Geo Forschungs Zentrum Telegrafenberg at Potsdam University، Germany.

Field observation shows that igneous host rocks in Esfordi were intensively altered by hydrothermal fluids. The ores are surrounded by wide altered halos. Petrographic investigation indicated that the most important alterations are of potassic، carbonatitic and silicification types. Magnetite and apatite occur as major minerals، accompanied by minor hematite and goethite in the mineralized zones. Rare Earth Element (REE) minerals are present as minor phases in the ores. Three apatite mineralization types (vein، massive، and disseminated) were recognized. Petrographic data represent three apatite generations: stage 1 which is recognized in the massive and disseminated ore types، stage 2 occurred in brecciated zones and stage 3 which is formed by dissolution and redeposition of the 1 and 2 apatite types in vein-shaped bodies. The correlations among major elements and SiO2 correspond to magmatic differentiation. Cerium is the most abundant REE in the studied samples. Similar REE distribution patterns were observed in the apatite، magnetite and host rhyolite. Electron Probe Micro Analysis (EPMA) shows that the apatites are of fluoroapatite type، enriched in LREE. Low content of Sr was detected in apatites of Esfordi. Low Cd and Na concentrations but high U and Th values were also detected in the studied ore samples.

Esfordi iron-apatite deposit is located NE of Bafq، Yazd Province، and in the Central Iran structural zone hosted by mainly Infracambrian rhyolites. Field evidence such as flow structure of ore and dendritic texture of some minerals، e. g.، actinolite reveal the magmatic origin of iron-apatite deposit. The trends of major element concentrations in ores from different rocks are consistent with magmatic origin of the ores. The absence of sulfides shows an oxidized condition of magma at the time of ore formation. Low Sr in the apatite however، rejects any carbonatitic magma at Esfordi (Belousova et al.، 2002). Similar REE distribution patterns in the apatite، magnetite and host rhyolite indicates the same origin for them. Cerium concentration in the ores from Esfordi is also consistent with magmatic ore types and negatively sloped REE distribution pattern and negative Eu anomaly resemble to the Kiruna type iron-apatite deposits (Hsieh et al.، 2008). Low Cd and variable Th/U in the apatite along with low Na are contradicting with sedimentary environment (Jami، 2005; Alves، 2008). The Esfordi deposit probably formed in an extensional arc-related setting associated with syn-collision granitoids.

There is an iron mining complex called Shahrak 60 km east of Takab town، NW Iran. The exploration in the Shahrak deposit (general name for all iron deposits of the area) started in 1992 by Foolad Saba Noor Co. and continued in several periods until 2008. The Shahrak deposit comprising 10 ore deposits including Korkora-1، Korkora-2، Shahrak-1، Shahrak-2، Shahrak-3، Cheshmeh، Golezar، Sarab-1، Sarab-2، and Sarab-3 deposits)Sheikhi، 1995) with total 60 million tons of proved ore reserves. The Fe grade ranges from 45 to 65% (average 50%). The ore reserves of these deposits vary and the largest one is Korkora-1 with 15 million tons of 55% Fe and 0. 64% S. The Korkora-1 ore deposit is located in western Azarbaijan and Urumieh-Dokhtar volcanic zone، at the latitude of 36°21. 8´، and longitude of 47°32´. Six thin-polished sections were made on magnetite، garnet، and amphibole for EPMA (Electron Probe Micro Analysis). EPMA was performed using a JEOL JXA-733 electron microprobe at the University of New Brunswick، Canada، with wavelength-dispersive spectrometers. Outcropped units of the area are calc-alkaline volcanics of rhyolite، andesite and dacite and carbonate rocks of Qom Formation in which intrusion of diorite to granodiorite and quartzdoirite caused contact metamorphism، alteration plus skarnization and formation of actinolite، talc، chlorite، phlogopite، quartz، calcite، epidote and marblization in the vicinity of the ore deposit.

The study area is a small part of the Urumieh-Dokhtar structural zone in the Markazi province، located in the northeastern part of the Farmahin، north of Arak (Hajian، 1970). The volcanic rocks studied from the area include andesite، dacite، rhyodacite، ignimbrite and tuff of Middle to Late Eocene age (middle Lutetian to upper Lutetian) (Ameri et al.، 2009). It seems that folding and faulting is caused in sedimentary basin and volcanic activities. On the other hand، except of orogeny maybe rifting had rule in eruption so that this case has seen in the other area such as Taft and Khezrabad in central Iran (Zarei Sahamieh et al.، 2008). The oldest formation in the studied area is Triassic limestones. The dominant textures of these rocks are porphyritic، microlite porphyritic، microlitic and rarely sieve-texture. Sieve texture and dusty texture (dusty plagioclases) indicates magma mixing. Mineralogically، they contain plagioclases، clinopyroxenes، amphiboles، quartz and biotite as the main constituents and zircon، apatite، and opaque minerals as accessories. Plagioclases in the andesitic and basaltic- andesite rocks are labradorite، bytownite and anorthite (based on electron microprobe). Moreover، plagioclases in andesitic rocks show that H2O is lesser than 2. 5 precent. Amphibole is found in both plagioclases and groundmass. In this article are used different analyses methods such as XRF، ICP-MS and EPMA. Whole-rock major and trace element analyses were determined with ICP-MS method. The major and trace element composition of some rock was determined by electron probe micro-analysis (EPMA) using a Cameca SX100 instrument in Iran Mineral Processing Research Center (IMPRC). Moreover، whole-rock major and some trace element analyses for some samples were obtained by X-ray fluorescence (XRF)، using an ARL Advant-XP automated X-ray spectrometer. Chemical data based on electron micro probe studies of minerals indicate the presence of labradorite، bytownite، anorthite as the plagioclases in volcanic rocks، as well as augite، pigeonite and clinoenstatite among the pyroxenes are abundant. Microscopic study of these lavas and pyroclastic rocks show evidences of magmatic contamination in the form of oscillatory zoning، resorption rims in plagioclase and presence of basic inclusions. The presence of oxidized amphibole rims (in hornblende) indicates the high temperature of the magma at the time of eruption. Based on geochemistry especially the ratio of Eu/Eu* is variable between liquid and solid phases. The calculated of this ratio in studied rocks show negative anomaly (Eu).

The study area is located 196 km south of Birjand in eastern border of the Lut block)Berberian and King، 1981) in eastern Iran between 59°05′35 «and 59°09′12» E longitude and 31°42′29 «and 31°44′13» N latitude. The magmatic activity in the Lut block began in the middle Jurassic such as Kalateh Ahani، Shah Kuh and Surkh Kuh granitoids that are among the oldest rocks exposed within the Lut block (Esmaeily et al.، 2005; Tarkian et al.، 1983; Moradi Noghondar et al.، 2011-2012). Eastern Iran، and particularly the Lut block، has great potential for different types of mineralization as skarnification in Bisheh area which has been studied in this paper. The goal of this study is to highlight the geochronology، geochemistry of major and trace elements، Rb-Sr، Sm-Nd isotopes for skarnified pyroxene-bearing diorites.

Major element compositions of thirteen samples were determined by wavelength-dispersive X-ray fluorescence (XRF) spectrometry، using fused discs and the Phillips PW 1410 XRF spectrometer at Ferdowsi University، Mashhad، Iran. These samples were analysed for trace elements using inductively coupled plasma-mass spectrometry (ICP-MS) in the Acme Analytical Laboratories، Vancouver، British Columbia، Canada. Zircon grains were separated from pyroxene diorite porphyrys using heavy liquid and magnetic techniques at the Institute of Earth Sciences، Academia Sinica، Taipei، Taiwan. Zircon U-Pb dating was performed by laser ablation-inductively-coupled plasma-mass spectrometry (LA-ICP-MS)، using an Agilent 7500 s machine and a New Wave UP213 laser ablation system، equipped at the Dr Shen-Su Sun memorial laboratory in the Department of Geosciences، National Taiwan University، Taiwan. Strontium and Nd isotopic analyses were performed on a six-collector Finnigan MAT 261 thermal-ionization mass spectrometer at the University of Colorado، Boulder، Colorado، United States. 87Sr/86Sr ratios were determined using four-collector static mode measurements. Several measurements of SRM-987 during the study period yielded a mean of 87Sr/86Sr = 0. 71032 ± 2 (error is the 2σ mean). Measured 87Sr/86Sr ratios were corrected to SRM-987 = 0. 71028. Measured 143Nd/144Nd was normalized to 146Nd/144Nd = 0. 7219. Analyses were conducted as dynamic mode، three-collector measurements. Several measurements of the La Jolla Nd standard during the study period yielded a mean of 143Nd/144Nd = 0. 511838 ± 8 (error is the 2σ mean).

In the Bisheh area that is located east of Lut block، pyroxene-bearing dioritic rocks are high-K calk-alkaline and meta-aluminous. Primitive mantle-normalized trace element spider diagrams display strong enrichment in LILE، such as Rb، Ba، and Cs، and depletion in some HFSE، e. g.، Nb، P، Ti، Y and Yb. Chondrite-normalized REE diagrams show (La/Yb) N ratios ranging from 7. 75 to 8. 63 and small negative Eu anomalies. These features along with high Th/Yb and Ta/Yb ratios show that magmatism is related to continental margin subduction. Obvious depletion of Nb and Ti، relatively high values of Mg#، initial 87Sr/86Sr (0. 70606) and 143Nd/144Nd (0. 512424) ratios as well as εNd (-3. 05) suggest that the magma originated from an enriched mantle with crustal contamination. High values of Rb، Th and K and low amount of P and Ti support the magma contamination in upper crust during magma evolution. Zircon U-Pb age dating for a porphyritic pyroxene diorite sample yield an age of 44. 07±0. 69 Ma indicating middle Eocene (Lutetian).

The isotopic value for the Bisheh dioritic porphyry can be considered as indicative of lithospheric mantle melting. The trace element characteristics of these rocks can be used to characterize their mantle source. The MORB normalized trace element pattern (Pearce، 1983) of all samples shows a negative anomaly for Nb، Ti and Ta. The negative anomaly of these elements can be explained by the presence of a residual TNT phase (Ti-Nb-Ta، e. g.، rutile، ilmenite and perovskite) during the melting of the source (Reagan and Gill، 1989). This pattern followed that of calc-alkaline magmas derived from a sub-arc mantle، with scarce or no garnet in the source. Furthermore، Bisheh subvolcanic bodies were enriched in Rb، Ba and Th، indicating that they had experienced interaction with the continental crust (Kuşcu et al.، 2002). The chondrite-normalized rare earth element pattern of the studied rocks shows a high ratio of light rare earth elements (LREE) to heavy rare earth elements (HREE). All the samples have been plotted in the VAG field. The dioritic rocks from the Bisheh have relatively high Mg# (0. 4-0. 56)، which is consistent with derivation from mantle melts contaminated by continental crust (Rapp and Watson، 1995). The initial 87Sr/86Sr of Bisheh pyroxene diorite porphyry was 0. 70606 and the (143Nd/144Nd) i isotope compositions and εNd value of these rocks was 0. 512424 and -3. 05، respectively. These values show that the magma originated from an enriched mantle with crustal contamination.