GEOCHEMISTRY
Year:2014 | Volume:3 | Issue:1|Papers Count:7

Pariz area is located in south-west of Kerman province, within the Urmia-Dokhtar volcano-plotonic belt and copper mineralization belt of Iran. The aim of this study is to identify the Cu high-potential areas in Pariz using stream-sediment geochemical studies. In this regard, 392 stream-sediment samples were used and they were analyzed by ICP-MES instrumental analysis for 15 elements. After applying the necessary pre-processing including replacement of censored data, remove the syngenetic component, outlier data correction and normalization; multivariate statistical processes were applied on data. Considering the vector origin of the stream-sediment samples, the network estimation method was used to produce geochemical maps. The geochemical maps were validated by the Cu occurrences in the region. According to the ratio of “percentage of overlay of the occurrences to the percentage of desirable area”, it can be stated that the enrichment index method has the best performance for identification of high-potential areas.

The Kuh-e-Surmeh Zn-Pb deposit is located in the south of Firuzabad and southeast Jahani salt diapir. The Ore body included: galena, pyrite and sphalerite were surrounded by brecciated dolomites as host rock. Upper Permian host carbonates show hydrothermal alteration process, solution and brecciation evidence. Microthermometric studies of calcite display that fluid inclusions are mostly primary in two phase (L+V) types. Homogenization temperature ranges in 72-145°C, and their salinity varies between 13-22.5 wt % NaCl. Based on the homogenization temperature and salinity, ore forming fluid could be basinal brines source. Geochemistry of trace elements indicates that Zardkuh Formation shale is enriched in Zn and Pb, so the shale is probably suggested for Zn-Pb for mineralization. Log Ga/Ge geothermometer, also indicates a metal precipitation from an ore bearing fluid which is taken place at 210°C.

Shahrood aquifer in Semnan province is affected by nitrate pollution sources such as domestic wells, agricultural return flow and industrial activities. These factors caused an increase of about 5.5 to 140 mg/L in groundwater nitrate concentration. In this research the transport and fate of nitrate in Shahrood aquifer was studied. Groundwater flow was firstly was simulated using MODFLOW code and the model was calibrated under steady and unsteady states and was verified for a period of 3-years. Then transport of nitrate was simulated by MT3DMS code. Initial and boundary conditions and transport mechanisms (advection, dispersion, diffusion and chemical reactions) of nitrate were considered and the model was calibrated based on the concentration changes in urban area during a period of 2-years. The results show that nitrate transport in Shahrood aquifer is greatly affected by groundwater flow direction and hydraulic conductivity. A zone of low hydraulic conductivity in the west and depression cones due to pumping wells concentration in the south of urban area, prevent nitrate spreading to the aquifer downstream. Denitrification process which decreases the nitrate concentration is probably not involved, because the urban area is located near the aquifer recharge zone where the oxidation conditions are prevailed. Based on the modeling results, nitrate concentration in urban waste waters recharging Shahrood aquifer varies from 70 to 450 mg/L. The risk zone of nitrate contamination in urban area was also investigated. Nitrate concentration in return flow from agricultural areas was calibrated at about 200 mg/L. Regarding volume of the return flows, about 152 kg nitrate is annually leached from Shahrood agricultural areas. In general, wastewaters recharge from Shahrood urban areas have the highest impact on the nitrate contamination of the groundwater resources.

The study area is located in NW Iran, within the 1:100000 geologic map of Ahar. The volcanic rocks of Eocene cover the large part of the area, being intruded by granitic-granodioritic and alkali-granitic intrusions of Oligocene age, which have produced hydrothermal alterations and Cu and Au mineralization. By taking in to account the very low detection limit of BLEG method for gold (0.1 ppb) and its rapid procedure for detecting very low contents of this metal within the stream sediments, this method was chosen for studying the geochemical distribution and anomalous zones of gold across the Ahar sheet. 422 stream sediment samples were collected and their Au content was determined by Fire Assay method. After processing the obtained data, 5 anomalous zones for gold were identified in the northern half of the area, as well as the central and southeastern parts of the Ahar Sheet. Based on field investigation, these anomalies are related to the alkali granitic and hornblende-biotite granitic intrusions and the hydrothermally altered zones.

Manganese deposits occur in association with ophiolite colored mélanges in Bashagard and Rudan areas, Hormozgan Province. The ore deposits are divided in three types: a) syngenetic, b) diagenetic-metamorphic and c) epigenetic ores. Psylomelane and braunite are the primary manganese minerals in syngenetic ores that were formed in sedimentary environment. The manganese compounds are found in alternative bands with amorphous silica and quartz. The diagenetic ores are characterized by the presence of bixbyite that is the product of braunite-hematite interaction. Lens-shaped structures of the manganese deposits hosted by siliceous rocks indicate the effects of diagenesis and metamorphism on primary banded structures. Metamorphism of greenschist, glaucophane schist and then amphibolite facies in some ores is indicated by the formation of manganese silicates and hydrosilicates e.g. johansenite in Bashagard and tephroite in Rudan. Progressive metamorphism in Rudan area is evidenced by the presence of rhodochrosite that is absent from Bashagard ores. Pyrolusite is the main manganese-bearing mineral from epigenetic ores that was formed by tardy hydrothermal process as open space fillings. High values of Mn/Fe (55.2), Si/Al (124.3), Zn (2-68ppm), ni (3-450ppm) along with negative anomaly of Ce, positive anomaly of Eu, low REEs in manganese ores are consistent with hydrothermal origin and the formation of the primary manganese compounds close to mid oceanic ridges above seafloor exhalation channels.

Due to the recent drought and indiscriminate use of groundwater in Kerman province, the reclamation of water quality is an important issue. Therefore, this study was done to remove calcium, magnesium, chloride and bicarbonate ions from wastewater by using pistachio shell and sawdust as organic absorbents and bentonite and zeolite as inorganic absorbents. In this regard, five treatments including; sand filter, sand-pistachio shell filter, sand-sawdust filter, sand-zeolite filter and sand-bentonite filter were applied. The results showed that the highest absorption of calcium (27.2%) and chloride (12.35%) was done by zeolite, which was attributed to the anionic adsorption. Also, the maximum absorption of magnesium (7.43%) was observed by pistachio shell, which was related to the cellulose surfaces of this absorbent negatively charged in water. The maximum absorption of bicarbonate (28.74%) was found by bentonite, which was demonstrated by two mechanisms of absorption and deposition. In general, among the applied organic and inorganic treatments, respectively pistachio shell and zeolite found as the best absorbents in the ions removal from wastewater. Also, comparison result indicated that inorganic adsorbents had higher efficiency than organic absorbents in removing calcium, magnesium, chloride and bicarbonate from wastewater.

The Quaternary volcanices in Khorsand and khatoonabad are located in Kerman province and in north-east and north-west of Shahre-Babak. These area are in south-western margin of central Iran and are between Nain-Baft ophiolite melange and Dehaj-Sardoieh (Dahaj-Sardoieh is part of Urumieh-Dokhtar magmatic series) Lithological units are vesicular basalt and variation bomb that based on microscopic studies are Olivin basalt and Pyroxene basalt. Their major minerals are Olivin (the three generations), pyroxene (the two generations) and plagioclase. Microlitic porphiritic vesicular is magor texture in these rocks. On the basis of geochemical analysis, magma that has formed the rocks had alkalin nature with a Na2O/K2O>1 ratio. The study of Rare earth element and trace elements patterns show that dip of variations have desending trend and indicate basaltic rocks inriched in LREE and LILE and depleted in HREE and HFSE. The study of Rare earth element patterns displays that magma orginated from an enriched asthenospheric mantle (garnet lherzolite). Based on La/Sm versus La plot the Khorsand and Khatoonabad basalts were formed by 6 to 8% partial melting of garnet lehrzolit parental rock. On the basis of solidification index (SI: 35 to 45%), these rocks arenot differentiation. The tectonic environment for the samples in discremenate diagrames is within continental plate setting. In Khorsand erea, the activity of Nain-Baft fault tensional tectonorigim and in Khtoonabad, lateral branches of Anar fault leading to thecreation of open fractures in crust which have conducted the flow of magma to the surface.