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

The present study aims to investigate the speciation, bioaccessibility, and health risk of Pb in the soils around the Irankuh mine. For this purpose, 20 soil samples were collected and the physicochemical parameters of the samples were determined. The total and bioaccessible concentrations of Pb were determined using the total digestion and in vitro methods, respectively. The speciation of Pb in selected soil samples was investigated using a sequential extraction approach. The values of pH, organic matter, carbonate and cation exchange capacity of the studied soil samples vary between 6.7 to 8.2, 0.2 to 4.8 %, 6 to 48.5%, and 18 to 11.2 meq/100 g, respectively. The total concentration of Pb changes between 18.4 and 2869 mg/kg (average value of 273.4 mg/kg). Pb is dominantly present in reducible fraction, confirming the anthropogenic source of Pb and its potential mobility. Based on the in vitro test results, the bioaccessibility of Pb is very variable (between 0.2 to 45.4% of the total concentration), which is due to the difference in the physico-chemical characteristics of the samples and the source of the element. The hazard coefficient values for ingestion, dermal contact and inhalation routes are higher for children than adults, and for the ingestion route than other exposure pathways. The carcinogenic risk (CR) values indicate that there is no risk through dermal contact and inhalation routes; however, CR values for the ingestion route using both bioavailable and total concentrations confirm the probability of cancer risks for residents living near the mining site.

Gardaneshir carbonate-hosted Pb-Zn deposit on the ground of study area located southwest of Ardestan in Isfahan province. Base on lithostratigraphy,the main structure, besides the small outcrops of Jurassic shales, has been made up of carbonate and detrital rock materials depending on Paleozoic,Triassic and Cretaceous time stages. Dolomitic carbonate which is attributed to Shotori Formation , played the major role of host rock in ore-mineralization. Ore-mineral description obtained from the mineralized zone and caused the following ore-paragenesis in ascending order.of:pyrite,chalcopyrite,galena,sphalerite,malachite,cerussite,smithsonite,iron oxides and gangues of barite, quartz and calcite. Physico-chemical information of ore-solutions performed by entrapped fluid inclusion studies in gangue minerals. Liquid-rich two phase(L+V) inclusions as predominant types were recognized. These type of inclusions are homogenized into liquid state with a range of TH and related salinities between; TH :78 to 183 and 216 to 283°C, Salinity:3.5 to 9.7 and 10.2 to 25 wt% NaCl eq. The microthermometric data reflect the nature of two population of fluid inclusions originating from different sources. The source materials could have been provided by basinal brines, derived during compaction of sediments in a shallow sea environment and by movement into sediments, the stratabound Pb-Zn deposit are formed. Furthermore, the negative delta value ranges(δ34S) from -0.6 ‰ to -20.4 ‰ that have been extracted by galena can be an evidence of bacterial sulfate reduction in a subsidence sedimentary basin. In conclusion, based on field, mineralogical, fluid inclusion and sulfur isotope evidence, we propose that Gardaneshir Pb-Zn deposit is a stratabound carbonate hosted of Mississipi Valley Type(MVT).

The Darreh Amrood Pb (Ag) deposit is located in south of Ghohrood, in the Urumieh-Dokhtar magmatic arc (UDMA). Host rockes to the deposit are Middle to Late Eocene grey-green siliceous tuff and crystal lithic tuff. Geometry of orebodies is stratabound, irregular, and semiconcordant to discordant to layering of the host rocks. Ore structures and textures are dominated by semi-massive to brecciated, banded and vein-veinlets. Main primary minerals are galena, pyrite and chalcopyrite, and secondary minerals are dominated by covelline, goethite and hematite. Gangue minerals are epidote, chlorite, sericite, clay minerals, quartz, calcite and barite. Wall rock alterations are dominated by epidote-chlorite and sericitic. The rare earth element (REE) pattern of ores is not similar to that of volcanic rocks in the footwall and hangingwall that is concordant with sub-seafloor replacement process for ore formation. Also Ce showed negative anomaly that can be attributed to Ce in the seawater. Also based on structural, stratigraphic, petrographic, textures, mineralogical, alteration and geochemical studies, it is inferred that the Pb (Ag) mineralization in the Darreh Amrood area occurred as bimodal felsic- or Kuroko-type volcanogenic massive sulfide (VMS) mineralization, and formed as sub-seafloor replacement. It should be noted that the Darreh Amrood deposit is the first recognition of base metal-rich and poor barite VMS mineralization in the UDMA.

This research study is based on  knowledge-driven approach to synthesize the different parameters which rule on the formation of carbonate hosted zinc and lead deposits. The analysis of available data sets of the north Irankuh district demonstrates the complexity of decision making due to the different anomalous prospects introduced by geophysical, geochemical and surface evidences.Five known deposit/active mines, namely Gushfil, Zone 1 Gushfil, Blind, Tapeh Sorkh and Zone 5 Romarmar with total geological resources quoted as 13.4 million tons at 5.53% combined lead and zinc (Fig. 10) were selected to be examined in order to asset a knowledge-driven approach to the exploration of carbonate hosted zinc and lead deposits. The diversity of geometry, mineralogy and host rock of the deposits is tightly confined by the parameters surrounding the genesis of MVT deposits such as genetics of solutions, temperature of deposit formation, tectonic channel ways, different episodes of deposition of sphalerite and galena, hydrologic system of area, solution direction, wall rock reactions (Leach et al., 2010), depth of solution penetration, solution response to the Magnesian regime and metal bearing.

The present study consists of detailed  underground and surface mapping, reinterpretation of district geology, detailed logging of about 100000 meters’ diamond drilling, ore geology, tectonic settings, deposits geometry, geochemical and geophysical survey within 7 square kilometers of north Irankuh district between the Gushfil and Tapeh Sorkh deposits.

Five known deposits in the north Irankuh district occur in the area of an intense detachment faulting (Fig. 1 and Fig. 5). The Gushfil, Zone 1 Gushfil and Blind deposits occur in north Irankuh reverse fault and Tapeh Sorkh and Zone 5 Romarmar in the trust fault. The deposits are confined to a certain stratigraphic unit locally called K3D (Figs. 2 and 3). Widespread regional selective dolomitization shows an extensive lateral movement from NW to SE and the depth of dolomitization in certain units drastically decreases. Two main regimes of solutions initially started with sphalerite and they were subsequently followed by galena the later of which is found in the secondary porosity. Mineralogy of the deposits is simple but the pyrite amount of the deposits varies from 2% to 20% which reflects the higher temperature of the solutions responsible for sulphide precipitation (Marie et al., 2001), geometry of the deposits and their distance to the current topography effect on chargeability values (Fig. 20).Sparry dolomite is found in three types as barren, with pyrite and light color sphalerite that occur in country rocks of all deposits except for the blind deposits. They can be used as a guide, addressing potential deposits.EPMA analysis revealed a considerable amount of Cadmium, Silver, Antimony, Arsenic and Copper within Sphalerite and Galena minerals (Fig. 12). Because of the semiarid climate in the area the decomposition of sphalerite, galena (Hitzman et al., 2003) and carbonate host rock has caused widespread distribution of Zn, Pb, Ag, Cd, Sb, As, Cu, Mn, Mg, Fe and Ca in the secondary halo of the area. The soil samples have been studied based on the static and machine learning methods (Figs. 13–A and B) by different researchers (Zekri et al., 2019). The anomalous areas based on geochemical studies have been tested by core drilling and the results are considered to be negative even in the area called Zone 3 which coincides with both geochemical and geophysical anomallies. In a different approach to understand the structure of geochemical elements the distribution of Zn, Pb, Ag, Cd, Sb, As, Cu, Mn, Ba together with elements such as Mg, Fe and Ca has been compared (Figs. 14, 15 and 16).The soils are heavily polluted due to widespread mineralization and no background value (Reimann and De Caritat, 2012) can be recognized.The comparative analysis of element concentrations in 5 selected populations in the studied area (Fig. 15) did not show any signs that could help  recognize important anomalies from the false anomaly. However,  it seems that the sudden decrease of Mg content (Fig. 17–C) in the area of Zone 3  (Zekri et al., 2019) is meaningful. Two geochemical profiles of soil samples crossing along this population and the next one crossing an active mine (Zone 5 Romarmar) (Fig. 18) provide us with a better understanding of the important anomalies versus the false anomaly since in the false anomaly the increase of Zn, Pb, Ag, Cd, Sb, As, Cu coincides with a sudden drop of concentration of Mg, Fe and Ca (Figs. 18–A and B). Recognition of ore containing strata (Sangster, 1995) is very important (Figs. 2 and 3) in locating successful drill holes in the exploration of carbonate hosted zinc and lead deposits. Eventually the use of data driven methods even opting advanced machine learning methods is not properly sufficient  to recognize  productive areas and we recommended the knowledge -driven approach.

Pb mineralization in Horeh area is located in 25 km northeast of Shahrekord, the middle part of Sanandaj-Sirjan zone in the mineralization belt of Malayer-Isfahan, in the geology map of 1/100000 of Chadgan (Ghasemi et al., 2005). There are nine mineralization belts, and 120 index mineralization of Pb-Zn has been identified based on paragenesis of mineralogy, time and type of mineralization in the Sanandaj-Sirjan zone. The Malayer-Isfahan mineralization belt is in the middle part of the Sanandaj-Sirjan zone, which formed in Mesozoic in carbonate sequences along with deep faults (Shahabpour, 1385). Often, this type mineralization is similar to Mississippi Valley-type (MVT) Pb-Zn deposits that many of these deposits have been created simultaneously with orogeny so that topographic slope is an essential factor in the ore fluids displacement (Leach et al., 2005, 2003, 2001; Appold and Gruven, 1999). The lithostratigraphy units in Horeh area include dolomite and limestone Permian, conglomerate, sandstone and shale Jurassic, limestone cretaceous, low grade metamorphic and young alluvium. The primary trend of the structure of the Hore Pb mineralization is NW-SE as same as the trend of the Sanandaj-Sirjan zone and the Zagros fault. This paper aims to identify the geological, geochemical and petrogenesis of the Pb mineralization on the base of the mineralogy, geochemistry, geophysics and fluid inclusion data. 

There are taken 35 samples and the number of 10thin section and 5 polished sections were prepared and studied in order to petrography and mineralogy. Major oxides (XRF method) elements were analyzed for 5 samples. 3 samples (calcite) were selected for Fluid inclusion study by linkam THMS-600 in Isfahan University. Data Geophysics was taken by  IPRSw-888 set and was measured Rs, Ip, Sp. 

Horeh Pb Mineralization occurred as lens and veins with a thickness of several centimeters to several meters in sedimentary rocks, with slopes and stretches of NW-SE and angle of 45°. This deposit is sulfide-type consists of galena, pyrite, and chalcopyrite as the primary ore and malachite, calcite and iron oxides as gangue. There are observed galen as fine-coarse grain, euhedral to xenomorph with triangular cleavage cavities, pyrite, and chalcopyrite as finely-coarse-grain, calcite as open space filling and comb texture, and veins in other rocks. Malachite often is formed by oxidation of the pyrite and chalcopyrite. Also, there are goethite, hematite, magnetite, illite, dolomite, and quartz. The mineralogical paragenesis sequence in Horeh area is two stages: the initial phase of the reduction that caused to deposit the sulfide minerals such as galena, and the second phase of the oxidation, which led to the formation of oxides and hydroxides minerals by initial carbonate and silicate minerals. Based on geochemical data, SiO2 =38.31% indicates to low maturity of sedimentary rocks compared to the upper crust (Taylor and McLennan, 1985; SiO2 = 64.8%). The high mean value of CaO = 25.22% (upper crustal crust = 4.19%) indicates to high amounts of carbonate cement, which cause to decrease of the relative amounts of SiO2 and Al2O3 in the samples. Al2O3 amounts are due to the clay and mica and Al-rich mineralogy, especially illite (Elsass et al., 1997). Fluid inclusion data of mineral calcite indicate to the two-phase of the fluid include (L + V) with irregular shapes in the size of 4 to 10 μm, and 136.6 ° C average homogeneity, -14.5° to -20° ice melting and 20.15% average salinity ( weight equivalent to NaCl)( Bodnar,1993). The result of fluid inclusion indicates to the basinal brines that is similar to the Pb deposits of the Mississippi Valley type. Geophysical investigations identified 4 Pb anomalies in the region, which begins at depths of 10 m and extends along NS and steep slope toward the west to the depth of 50 m by measure chargeability (PI), electrical resistivity (RS) and metal coefficient map (FM). 

The Pb mineralization in the Horeh area is as Galena with chalcopyrite and pyrite. Based on field study and petrography data, Galena is the main mineral and carbonate, and silicate minerals are gangue. Pb Mineralization has occurred as the replacement, bedding and tangential in the Jurassic formations by basin brine fluid.  The combinations of field study and mineralogy, geochemical and geophysical data indicated to the similarity Pb deposit of the Horeh to the Mississippi type that was formed during the two-stage reduction and oxidation. Geophysical data were indicated to the, 4 Pb anomalies from 10 m the topography level with 50m thick with the steep slope to the west.

The Varandan Ba-Pb-Cu deposit is located in southwest of Qamsar which is part of Urumieh-Dokhtar magmatic-arc zone. Mineralozation occurred as four sub-horizons in the unit1 of volcaniclastics and volcanics (acidic tuff and andesite) of Middle-Late Eocene. Each sub-horizon consists of five ore facies including: 1) stringer zone, 2) vent complex zone, 3) massive zone, 4) bedded-banded zone and 5) hydrothermal-exhalative sediments of Fe and Mn bearing. Main wall rock alterations in the deposits include chloritic-quartz and quartz-sericitic. Alteration zoning is observed in the deposit as chloritic-quartz at the core and quartz-serisitic in the margins of the footwall of the ore sub-horizon. Electron microprob analysis (EPMA) on the chlorite in stringer zones of the second and third sub-horizons show that these chlorites are Fe-rich chlorite and close to the clinochlor field. Geochemical studies indicate that grades of Ag, As, Cu, Sb and Sr in the stratiform ore (bedded-banded and massive) of the third sub-horizon are much higher than the other sub-horizons, and are 41, 273, 1945, 390 and 1013 ppm, respectively. All geochemical studies show that metal zoning in this deposit is clear, this is characteristic of VMS deposits. Development of zone-refining and over refining processes caused leaching of Cu from the stringer zone and vent complex facies and its later precipitation in the bedded ore facies. Among across to different sub-horizons in the Varandan deposit, third sub-horizon is recognized as economic for Ag extraction .

The early Cretaceous sedimentary sequence in south of Yazd hosts numerous Zn-Pb-Ba mineralization horizons. The sequence based on the stratigraphic position, age and composition of the rocks, can be divided into tree lower, middle and upper parts. The lower part or Sangestan formation mainly formed from clastic sedimentary rocks such as conglomerate, sandstone, shale, siltstone and oolitic limestone. The thick Sangestan sedimentary sequence is well exposed resting unconformably on the Jurassic Shir-Kuh granite and metamorphic Shemshak Group. The middle part or the Taft formation include organic matter-rich shale, siltstone, limestone and dolomite. The upper part or the Abkuh (Darreh-Zanjir) formation comprised of shale, chert-bearing bedded limestone and marls, overlying concordantly on the Taft formation. The Zn-Pb-Ba mineralization horizons within the sedimentary sequence, based on stratigraphic position, relative age and type of host rocks involved the two horizons: the first horizon consisting of Mehdiabad, Farahabad and Mansourabad deposits, occurred in the lower part of the Taft formation and hosted by organic matter-rich shale, shaly limestone, siltstone, silty limestone and dolomite. The second horizon comprising Mehdiabad and Mansourabad deposits are hosted by black shale and chert-bearing bedded limestone locates within the middle part of the Abkuh formation.

Mahabad reservoir dam is the main drinking water source for Mahabad town and its downstream villages. To investigation of water quality, the physicochemical parameters including pH, Eh, EC, TDS, total hardness (TH), total alkalinity (TA), temperature, salinity, concentrations of main cations and anions (for 5 samples) and some of the heavy metals (for 11 samples) were measured in water sampling stations. According to the chemical analysis results and compare to the international standards, main cations and anions concentrations and physicochemical parameters values (exception total hardness) of the water samples are located in permissible ranges and suitable for drinking water. Compare to the world health organization (WHO) standards, all of the water samples indicate Cd and Pb pollution, point of view of drinking water. In KDT3 sampling station, the concentration of Cd and Pb are 26 times and 3.5 times of permissible values, respectively. Also, the water of Mahabad reservoir dam and upstream tributaries are polluted regarding to Cd for livestock and poultry requirements. These pollution can be related to geogenic source (mineralization) and anthropogenic source (wastewater derived from upstream villages). But for irrigiation, the water of Mahabad reservoir dam and upstream tributaries have low salinity (C2S1 class) and suitable for agricultural uses. Piper diagram revealed bicarbonate type and calcic facies for water of Mahabad reservoir dam. The surface water of the study area, for the reason of high total hardness, needs to softening prior to use for different industries.

Deformed granitoid rocks North Saman represent part of magmatic activity in the Sanandaj-Sirjan zone during the Mesozoic. The granitoid rocks intruded as separate intrusions into the metamorphic rocks with protolith ages of the Palaeozoic and Mezosoic. These granitoids are deformed as a result of subsequent tectonic activities. Zircon U-Pb ages of crystals separated the granitoid rocks gave ages of 182 ± 4 Ma and indicate that the granitoid rocks crystallized at the Toarcian stage of the lower Jurassic. The major and trace element goechemistry suggests a subduction-related, active continental margin setting for the granitoid bodies. The occurrences of numerous Jurassic granitoids reveal the importance of magmatic activities during this period in the Sanandaj-Sirjan zone.

In this research، the bioleaching process of mixture of sulfide and carbonate zinc and lead ore of Angouran Mine، whit local mixed mesophilic bacteria was studied. The purpose of this study was to indicate the effects of pulp density، Fe (II) concentration and initial pH in the zinc and lead bioleaching. In Addition، the pH and Reduction-Oxidation Potential (ORP) have been monitored and evaluated during bioleaching process. The results showed that the zinc recovery through the bioleaching process (64. 4 %) was much more than the leaching without bacteria (33. 56 %). The results also showed، an increase in the pulp density caused a decrease in zinc recovery، and an increase in initial pH and ferrous concentration increased the zinc recovery. On the other hand، maximum lead recovery was 1. 03 %. The study of bioleaching residual showed that the lead was recrystallized as Pb5 (AsO4) 3Cl. However، presenting the relation between mentioned parameters and Pb recovery was impossible due to lead precipitation. The results of this research could be used for bioleaching of high-grade Pb-Zn ores.

Gomish-Tappeh Zn-Pb-Cu (Ag) deposit is located in northwestern part of Urumieh-Dokhtar volcano-plutonic zone، 90 km southwest of Zanjan. Exposed rocks at the area include Oligo-Miocene volcano-sedimentary and sedimentary sequences as well as Pliocene dacitic subvolcanic dome، rhyodacitic volcanics and andesite porphyry dykes. The main mineralization at Gomish-Tappeh deposit has occurred in a steeply deeping normal fault and fracture system defined by NE-SW trend in three stages including hydrothermal breccias، silicic-sulfidic، silicic-sulfidic-carbonate veins and veinlets and late banded veins (rich in silica and specularite). Host rocks to mineralization include dacitic crystal lithic tuff، dacitic subvolcanic dome، and specifically acidic tuff. Paragenetic minerals at the deposit consist of pyrite، arsenopyrite، chalcopyrite، bornite، galena، low-Fe sphalerite، tetrahedrite، tennantite and specularite. The main alteration types at the area are silicic، silicic-sulfidic، sericitic، carbonate، argillic and propylitic. Based on element distribution and frequency patterns in the ore samples، among base metals، Zn، Pb، Cu and Ag show the highest concentrations. Average grades in the ore veins at Gomish-Tappeh deposit are: 6% Zn، 4% Pb، 2% Cu، 88 ppm Ag and 44 ppb Au. Fluid inclusion microthermometric studies on quartz crystals of the first and second stages of mineralization indicate homogenization temperatures of 260-367 °C، salinities of 9. 1-16. 9 wt% NaCl equiv.، and approximate mineralization depth of 956 m below the paleowater table. Considering high salinity fluids and base metal contents، it is likely that base metals and silver were transported by chloride complexes. Fluid inclusion studies، hydrothermal breccias، banded-colloform-crustiform textures and amorphous silica indicate that boiling is the main factor for instability of the complexes and eventually، ore deposition.

The Sar Cheshmeh mine، a world-class porphyry copper deposit، is located in the Kerman metallogenic zone. The rock outcrops in the deposit are Eocene basalt، basaltic andesite and andesite، Oligocene granular and porphyry granodioritic intrusions and Miocene Sar Cheshmeh granodioritic porphyry stock، granitic late fine-grained porphyry and andesitic to dacitic hornblende، plagioclase، and biotite porphyry dykes. In the spider diagrams، studied rocks show LILE enrichment and HFSE depletion pattern similar to volcanic arc rocks. Eocene volcanic rocks and Oligocene granular and porphyry granodioritic intrusions represent typical magmas characteristics of volcanic arcs whereas Miocene intrusions and dykes have adakitic nature. The (La/Yb) N ratio in the volcanic rocks and Oligocene intrusions varies between 1-5 and 7-11 respectively، while Miocene intrusions and dykes show highest amount of this ratio (20-40). Low aboundancy of HREE in the Miocene intrusions and dykes implies that garnet have been in the source، which has been formed due to increasing crustal thickness during Oligocene and Miocene. According to U-Pb dating، the Sar Cheshmeh porphyry stock and granitic late fine grained have been emplaced in 12. 97 ± 0. 23 Ma and 12. 37 ± 0. 1 Ma respectively، while hornblende porphyry dykes has been intruded in 12. 16 ± 0. 8 Ma. According to trace element characteristics in zircon crystals، Miocene intrusions and dykes originated from same source. Middle Miocene intrusions and dykes have been generated in a post collisional tectonic setting from various degree partial melting of amphibolitic mafic lower crust with variable garnet.

Tappehsorkh Zn-Pb- (Ag) deposit، hosted by Lower Cretaceous siltstone، tuff and dolomite، is located in the northern part of the Irankuh mountain range، south of Esfahan. Sulphides in this ore have a relatively simple mineralogy including sphalerite، galena، tetrahedrite، pyrite and to a lesser extent، chalcopyrite، marcasite and bornite. Gangue minerals are predominantly dolomite، quartz and barite. Based on zoning in the sulphide mineralization، texture and structure and location of ore facies relative to syn-sedimentary normal faults، theses ore facies are classified as vein-veinlet، laminated and massive. Dolomitic-silicic alteration is among the major processes concomitant with sulphide mineralization. The greatest degrees of alteration and related ore mineralization occur at the vicinity of the normal faults and decrease away from it. Geochemical studies indicate that the ore-bearing fluids were of oxidized composition، which were reduced once reaching favorable host rocks and consequently deposited sulphide minerals. Minor and trace element studies in the various sulfide ore facies demonstrate that the ore-bearing fluid in all the ore facies has a similar composition. Textures such as framboidal pyrite، contemporaneous folding of organic matter along with sulphide lamination in the laminated ore facies، and diagenetic structures such as load casts in the host siltstone indicate that sulphide mineralization has occurred in the sedimentary-diagenetic stage. However، sulphide mineralization in the regional dolomite is considered to have occurred in a shallow diagenetic environment because of replacement of regional dolomite by hydrothermal dolomite. Based on features of ore mineralization such as the extensional tectonic setting، siltstone and carbonate host rocks، and occurrence of various sulphide facies such as vein-veinlet، laminated and massive، the Tappehsorkh deposit is very similar to Sedex-type deposits.

The Sungun porphyry copper deposit is located in the NW of Iran. Most rock outcrops in the region and the surrounding area comprise the Cretaceous metamorphosed and skarnish carbonates and the Eocene volcanic rocks that intruded by the Sungun monzonitic to quartz monzonitic stock. The Sungun stock crosscut by late-and post mineralization dykes. The Sungun porphyry stock was emplaced in 21 Ma ago and then late-and post mineralization dykes intruded at the 19.78 and 19.51 Ma ago, respectively. Zircon trace element data indicates that all the studied zircons are magmatic in origin and the source of the Sungun porphyry monzonite is different from late-and post mineralization dykes. According to Ti-in- zircon thermometry, the porphyry Sungun stock and the late dykes were crystalized at about 650 and 700 °C, respectively. Rare earth element abundances in the zircon crystals show that the Sungun porphyry has crystallized from productive and high ƒO2 melt. Our dating results indicate that porphyry mineralization in the Arasbaran belt occurred in the early Miocene time and about 10 m.y. earlier than the Kerman belt and in a post-collisional tectonic setting.

The Touzlar epithermal gold deposit formed within the high-K calc-alkaline (shoshonitic) andesitic volcanic units in northwestern Iran. The volcanic complex is in fact a part of magmatism related to the Urumieh-Dokhtar Magmatic Belt crosscutting northeastern rim of the Sanandaj- Sirjan Metamorphic-Magmatic Zone. This magmatic system is composed of pyroclastics and lava flow sequences. The volcanic and subvolcanic rocks of the complex constitute a part of the volcano-sedimentary sequence of the Qom Formation, which formed in an extensional regime of basement uplifting and intra-continental basin. Zircon LA-ICP-MS U-Pb dating shows age between 18.4±1.0 and 18.7±0.55 Ma (Lower Miocene) for the volcanism. The hydrothermal alteration types (propylitic, argillic, phyllic, sericitic, advanced argillic and silicification) and evolving mineralization in relation to brecciation and deposition of copper sulfides and sulfosalts imply that the mineralization at Touzlar is similar to that of high sulfidation deposits in volcanic settings. The gold mineralizationtextures in the Touzlar deposit appear as disseminated, open space filling, veins and veinlets. The main sulfide minerals are pyrite, chalcopyrite, bornite, as well as small amounts of enargite, chalcocite, covellite, digenite, tetrahedrite, galena and sphalerite. The gold in this mineralization occurs as freed from oxidized pyrite grains, also in quartz in hydrothermal breccias as well as solid solution in other minerals such as sulfides and sulfosalts. The main difference in the formation of Touzlar with high sulfidation deposits is in its setting. The formation setting for this mineralization confirms its genesis at low depth and pressure. The deposit formed at the shallow submarine environment of the Qom basin in relation to extensional tectonic regime, while high sulfidation epithermal deposits usually form in subaerial environments related to tensional settings. Structural, host rock type, alteration, paragenesis and Au-Ag (Cu) ore mineralization characteristics of the deposit suggest that Touzlar is most similar to subvolcanic intrusion-related epithermal (high sulfidation) gold deposits formed in intra-arc extensional settings.

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.

Adsorption is one of the effective and frugal methods that used for removal of toxic metals-such as lead- from wastewater. In this paper، effect of three parameters including pH، adsorbent dosage and initial concentration of lead has been studied by two inexpensive adsorbents including natural goethite and Hormoz island ochre. The effect pH on lead adsorption by each of adsorbents shows that lead adsorption percent increase with pH increasing to 5%. On the other hand، experiments showed that with increasing adsorbent dosage، adsorption percent increase in both adsorbents. But ochre unlike goethite has high ability for lead adsorption even in adsorbent dose 2 g/L. Investigations showed that in high lead concentrations ochre toward goethite is more effective adsorbent for lead. So that ochre under condition with initial concentration 150 mg/L، ambient temperature (23. 5◦C)، pH=5، adsorbent dose 6g/L، reaction time 60 min and particle size smaller than 230 mesh removes 97. 57% of lead. Goethite removes 78. 53% of lead at the same condition. In this condition، maximum lead adsorption capacity for ochre and goethite is 24. 39 and 19. 63mg/g respectively. Initial concentration and adsorption percent shows direct relation for ochre، but reverse for goethite. Langmuir and Frundlich adsorption isotherms show that goethite follows Langmuir model with correlation coefficient of 0. 995، but ochre almost follows both models of Langmuir and Frundlich.

The Takht- e baz granitoid in the northwest of Birjand is cropped out in the vicinity of pyroclastic units composing of tuff، marly tuff and breccia. Petrography and major elements analysis show that this intrusion is alkali granite to granite in nature. Common textures in these rocks are granular، graphic، myrmekite، granophyric and perthitic. Potasium feldspars (perthitic orthoclase and microcline)، quartz and sodic plagioclases are essential minerals. Biotite as the only mafic mineral and zircon، titanite and Fe-oxide are the accessory minerals of these rocks. Biotite is altered to chlorite، and feldspars to sericite، calcite and clay minerals. Age dating with zircon uranium-lead method indicated that the alkali granite is 55. 7 ± 0. 6 Ma (early Eocene) old. Chemically، the rock suite is characterized by high total alkali، Fe/Mg، Ga/Al، Hf، REE (except for Eu)، SiO2 and Zr and low contents of Ba، CaO، MgO، P2O5 and Sr. These features along with various geochemical discrimination diagrams suggest that the Takht-e baz granitoid is post-collisional A-type (A2-type). This suite may be derived from melting of continental crust in an extensional setting after collision of the Lut and the Afgan continental blocks in the east of Iran.

Tangedezan Zn-Pb deposit is located in 22 km west of Booeen Miandasht city, in western part of Isfahan province and in Malayer–Isfahan Pb-Zn mineralization belt. This deposit is one of the stratabound deposits in a Jurassic Cretaceous carbonate sequence. Two main ore body geometries have been recognized in the deposit: 1-layers and lenses, concordant with layering; and -discordant secondary forms along the fractures. In Tangedezan deposit two mineralized carbonate facies have been distinguished: 1- dolomitic limestone facies (Microsparite) containing three major mineralization horizons with simple ore mineral paragenesis such as galena, sphalerite and pyrite replacing the host rock and filling the porosities and fractures; and 2- crystallized argillaceous limestone facies with very weak Zn-Pb mineralization in disseminated form. The deposit includes two parts of supergene in surface and sulfides in depth. The simple ore paragenesis comprises of hemimorphite, smithsonite, cerussite, galena, sphalerite and pyrite. Ag and Cd elements have noticeable grade and could be contemplated as by product. All accomplished investigations and evidences such as geological characteristics, mineralized facies, supergene and sulfide development, ore body geometry, ore minerals paragenesis, texture and structures in different scale, existing alterations specially dolomitization and lithogeochemical studies all reveal that Tangedezan deposit is a Zn-Pb Mississippi Valley Type (MVT) deposit.