جستجوی مقالات مرتبط با کلیدواژه "آذربایجان شرقی" در نشریات گروه "زمین شناسی"

The Oligocene dacitic volcanic rocks display widespread exposures in south of Julfa (eastern Azerbaijan). They generally show porphyritic to hyalo-porphyritic textures with major minerals of plagioclase, amphibole, quartz and biotite. Electron probe micro analyzer (EPMA) data indicates oscillatory zoning and chemical variation of amphiboles (pargasite and edenite). The plagioclase crystals are, chemically, andesine (An= 29-51%) which mostly display oscillatory zoning. Based on geobarometric calculations, plagioclase displays pressures of 5 to 8 kb and amphiboles demonstrate different pressure ranges of 1.5 to 3 and 5 to 9 kb. Moreover, geothermometric calculations of plagioclase and amphibole provide temperatures of 1020-1050 and 850-900 °C, respectively. On the basis of geobarometric results, crystallization and growth of the minerals took place in magmatic chambers of different levels. Some of the amphiboles nucleated in lower continental crust and subsequently grown during magma ascent in middle crust whereas some others crystallized in the upper continental crust. Therefore, existence of minerals of different levels inside the studied rocks could be related to magma mixing in shallow magma chambers.

It is generally understood that manganese deposits have a diverse origin, based on their mineralogy, chemical composition and tectonic setting. Marine Mn-bearing deposits are classified as hydrogenous, hydrothermal and also biogenetic-bacterial deposits (Bonatti et al., 1972; Hein et al., 1997; Bau et al., 2014; Polgári et al., 2012; Schmidt et al., 2014). Hydrogenous processes can form ferromanganese crusts, which result from slow precipitation of seawater at the seafloor often via microbial mediation (Toth, 1980; Dymond et al., 1984; Bau and Dulski, 1999; Usui and Someya, 1997; Hein et al., 2000; Jach and Dudek, 2005). Diagenetic manganese deposits occur as nodules and precipitate from hydrothermal solutions or pore water (Polgári et al., 1991; Oksuz, 2011; Polgári et al., 2012), whereas hydrothermal ore deposits are stratabound or occur as irregular bodies and epithermal veins, where they are formed in a marine environment near spreading centers, intraplate seamounts or in subduction-related island arc setting (Roy, 1992; Roy, 1997; Hein et al., 2008; Edwards et al., 2011).

Eighteen Ore samples (~ 500 g each) were collected systematically from the Gezeldash Daghi manganese deposit. All these ore samples were taken representatively from the surface outcrops ore beds in different places for geochemical analyses. Ore samples were powdered under 200 meshes and analyzed at Iran mineral processing research center laboratories, Tehran. After being prepared by the Lithium Borate Fusion method, their major oxide and trace element contents were determined with ICP-OES. The results of the analyses are given in Tables 1 and 2.

The deposit is hosted in various lithology and horizons consisting of: 1) tuffite interlayered with limestone, 2) conglomerate and sandstone lithology into volcano-sedimentary basin located at 25 km northwest of Marand city (N38°35ʹ40ʺ, E45°42ʹ40ʺ). Major and trace element assessments show that hydrothermal solutions were effective in the formation of the Gezeldash Daghi manganese deposit. Also, field observations reveal that manganese mineralization occurred as laminated-layered and fracture-filling form in limestone and tuffite at horizon I and the space-filling form between conglomerate clasts and veinlet form in sandstone at horizon II with quaternary age. Therefore, it can be concluded that hydrothermal solutions were caused in the formation of the manganese deposit which may be described as related to volcano-hydrothermal occurrence.

The Noghduz  prospecting area, as a part of the Arasbaran metallogenic zone is located about 20 km east of Ahar, East-Azarbaijan Province. The mineralization host rocks are andesite-trachy andesite with the age of  Late  Eocene. The hydrothermal alterations exposed in this area are silicic, argillic, and propylitic. Pyrite is the main hypogene sulfide mineral which is accompanied by lesser amounts of chalcopyrite and bornite. The most important supergene minerals in this area are iron oxyhydroxides (hematite, limonite and goethite) and malachite that accompany the hypogene mineral assemblage. Gold mineralization occurred within quartz-sulfide veins/veinlets in this area. The microthermometric measurements in the primary 2-phase (L+V) fluid inclusions in quartz crystals associated with  mineralization  indicate that  the mineralizing fluids had temperatures and salinities within the range of 160-334°C and 0.53-3.39 wt% NaCl equivalent. respectively. The presence of hydrothermal breccias, pseudomorph of quartz after bladed calcite, and mono-phase gas inclusions are indicative of boiling of the hydrothermal fluids responsible for mineralization. The sulfur isotopic analysis of pyrite shows  that  the values of isotopic composition of this element  is  close to the range of magmatic source. Also, the oxygen and hydrogen isotopic data demonstrated that  the meteoric waters constituted a great portion of the ore-bearing fluids at Noghduz area. The presence of structural and textural evidence along with fluid inclusion studies (salinity and homogenization temperature) indicate that the gold mineralization at Noghduz area is of epithermal type.

The Zailic gold-bearing veins are located in the Arasbaran metallogenic zone, east of Ahar, East-Azarbaidjan Province. The most important lithologic units in this area are andesitic and trachy-andesitic tuffs and lavas of Upper Eocene age hosting vein-type gold mineralization. Theses rocks have suffered silicic, argillic, phyllic, and propylitic alterations brought about by hydrothermal fluids. The geochemical study of alteration zones in this area showed that in the silicic zone, due to the acidic nature of altering fluids and hence intense leaching, depletion of most major and trace elements took place. The degree of leaching towards the propylitic zone, owing to the pH increase of the hydrothermal fluids, gradually decreases. The presence of minerals with high adsorption capacity, such as clay minerals, resulted in concentration and fixation of many elements in the argillic, phyllic, and propylitic zones. Consideration of the behavior of rare earth elements (REE) in silicic zone relative to almost fresh volcanic rocks showed that most of REE suffered depletion. Geochemical indices such as TiO2 and (Ce + Y + La)-(Ba + S), showed that the hypogene hydrothermal fluids played an important role in the development of alteration zones at Zailic

The Skavagh study area is located in the western of the Alborz-Azarbaijan folded belt. The dominant rocks in this area are volcanic and volcanic-sedimentary rocks with the Eocene-Oligocene age which have covered most of the area. As well, the late Oligocene intrusive bodies with intermediate composition have cut the rocky units of the area. Generally, metal mineralization in the Skavagh area is copper and manganese which has occurred in the Eocene volcanic and volcanic-sediments rocks. In this research, satellite images of Sentinel 2 and Landsat 8 have been used to perform different methods of supervised classification and prepare a geological map. In this study, after performing the necessary pre-processing, the supervised classification of the images was carried out in different ways, and finally, by conducting field studies, the best method was selected based on the geological evidence. Finally, after calculating the error matrix, the accuracy of the data, Kappa coefficient and by comparing with the index samples and sampling and the thin sections of the geology, the method was validated. After sampling and statistical analysis, it was determined that the spectral angle mapping method showed the best match with the geological units of the region.

  The East Azarbaijan geothermal area is located in northwest of Iran, which hosts several hot springs. It is situated mostly around the Sabalan and Sahand mountains. The Sabalan and Sahand geothermal area is now under investigation for the geothermal electric power generation. It is characterized by high thermal gradient and high heat flow. In this study, our aim is to determine the fractal parameter and top and bottom depths of the magnetic sources. A modified spectral analysis technique named “de-fractal spectral depth method” is developed and used to
estimate the top and bottom depths of the magnetized layer. A mathematical relationship is used between the observed power spectrum (due to fractal magnetization) and an equivalent random magnetization power spectrum. The de-fractal approach removes the effect of fractal magnetization from the observed power spectrum, and estimates the parameters of the depth to top and depth to bottom of the magnetized layer using iterative forward modelling of the power spectrum. This approach is applied to the aeromagnetic data of the East Azarbaijan Province. The obtained results indicated variable magnetic bottom depths ranging from 9.8 km to about 16.8 km. In addition, the fractal parameter was found to vary from 1.6 to 3 within the study area. The interpretation of potential fields is generally carried out in the frequency domain due to (1) simplicity in the implementation of signal processing tools, and (2) easy and concise characterization of potential field signals caused by a large variety of source models. In the frequency domain, the geophysical source parameters such as density have been assumed as uncorrelated distribution. To the contrary, source distribution of the physical parameters is correlated following the scaling or fractal laws. Fractal source distributions have power spectra proportional to , where k is the wave number (i.e. length of the wave vector) and β denotes the respective fractal parameter. This has been discovered by the detailed analysis of the densities
and susceptibilities of several borehole data around the world including the German continental deep drilling program in southeastern Germany. The fractal parameter reflects the proportion of long and short wavelength variations of a signal. The higher the value of the fractal parameter, the stronger is the relative intensity of the long wavelength variations of the signal. The main objective of the current work is to develop an algorithm for estimation of the fractal parameter using a defractal spectral analysis of the aeromagnetic data from the study area in order to determine the bottom depths of magnetic sources. This approach for analysis of magnetic data assumes that the observed power spectrum is equivalent to the random magnetization model multiplied by the effect of fractal magnetization. It is believed that the de-fractal method can reduce the ambiguity related to the selection of fractal parameter to provide an estimate of bottom depths of magnetic sources more reasonable than the estimates using conventional methods. However, the ability of the de-fractal method has not been verified so much in practical exploration applications. Hence, in this work, an attempt has been made to use this approach to remove the effect of fractal magnetization from the power spectrum of real magnetic data to have a reasonable depth estimate of magnetic sources. In the last four decades, variations on several methods have been proposed and applied for estimation of the bottom depths (zb) of magnetic sources using azimuthally averaged Fourier spectra of magnetic anomalies. The mathematical formulae of these methods are based on assumptions of flat layers with particular distributions of magnetization, namely: 1) random (uncorrelated) magnetization models or 2) self-similar (fractal) magnetization model. The idea of using models with fractal magnetization distribution comes from the concept of self-similarity. The de-fractal method is based on the assumption that the observed power spectrum is adequately represented by a simplification of the fractal magnetization power spectrum where the magnetization in the x and y directions is fractal and is constant in the z direction. In this case, the observed power spectrum is equivalent to the result of power spectral density of the random magnetization model multiplied by k-α. Having removed the fractal effect, one can treat the resulting de-fractal power spectrum as though it was the power spectrum of a random magnetization model. The present approach can be considered as a correction to the power spectrum of the magnetic field for the fractal distribution of magnetization. In this work, we have determined the bottom depths to magnetic sources using de-fractal spectral analysis method. This method applies a transformation to the observed magnetic field based on an estimated fractal parameter such that the power spectrum resembles the power spectrum that would be generated by a random magnetization distribution. The advantages of this method are that the range of the feasible de-fractal parameters can be estimated, and the bottom depths of the magnetic sources or anomalies are obtained based on simultaneously estimating the depth values from the centroid method and visual inspection of the forward modeling of the spectral peak. The method has been applied to 50% overlapping 11 blocks having 100 * 100 square km dimensions of aeromagnetic data in Ardabil area. As a result, the fractal parameter has been determined between 1.6 and 3 The obtained results also indicate that the bottom depths of
sources of the magnetic anomalies vary from 9.8 km to about 16.8 km.

Karghan Area is located in East Azarbaijan province, southeast of Tabriz and northwest of Bostanabad city. Based on the division of the structural zones of Iran, it is part of the Alborz-Azarbaijan zone. The most important geological units in the studied area are shale, marl and limestone (Cretaceous), Sahand volcanic products of the age of Pliocene-Pliocoscene, Granitic intrusive, Gabrodiorite and Monzogranite, old terraces and Quaternary sediments. Regarding the spread of the area, 29 geochemical stream sediment samples and 29 heavy mineral samples were taken from the places. The anomalies of arsenic, barium, copper, lead and zinc in the region are represented by their statistical distribution type. The most important heavy minerals with lithological origin were zircon, amphibole and pyroxene. Heavy minerals of pyrite, magnetite and hematite are attributed to the mineralization holes. Heavy mineral studies indicate occurrence of malachite-copper mineralization in the region. Considering the observed anomalies in the stream sediments and heavy minerals, it is recommended detail exploration in the area

The Ghikhlar area is located at the NW Marand town, East Azarbaidjan. The wide range of Plio-Quaternary volcanic activites with volcanic and associated volcano-clastic rocks having compositions mainly as andesite to silica-undersaturated rocks (leucite basanite, leucite-tephrite and tephrite) have been covered mostly the rock units prior to the Cenozoic. The phenocrysts in andesites are amphibole, plagioclase and clinopyroxene which occurred in microcrystalline and microlithic matrix. The main characteristic of these rocks is bearing various enclaves as autholiths and xenoliths. The clinopyroxenes in the host andesite and cumulative enclaves are diopside to augite. The autholithic andesitic and dioritic enclaves indicates compositions as augite and dipside, respectively. Investigation of mineral chemistry and magmatic features for the host andesitic rocks and their enclaves are the main goal of this research. Variety of magmatic enclaves are including homogenic, cumulative and gabbroic ones. They all show similar mineralogy with host andesitic rocks whereas they are different texturally. Homogenic and gabbroic enclaves are more fine and coarse grained than host andesite, respectively. Cumulative enclave has been formed as aggregation of coarse grained ferromagnesian crystals similar with phenocrysts of andesite. On the basis of mineral chemistry data, composition of the host andesite as well as homogenic and cumulative enclaves are subalkaline with arc magmatic tectonic setting feature. However gabbroic enclave with alkaline characteristic corresponds to interior plate tectonic setting. Considering mineralogy, textural evidence and mineral chemistry data from the host andesite and their magmatic enclaves it can be concluded that the homogenic and cumulative enclaves are autoliths. The homogenic enclave corresponds to chilled margin of magma reservoir which disjoined during upward ascending of andesitic magma and their falling into magma chamber. Cumulative enclave resulted from aggregation of magmatic minerals in the magma chamber. About genesis of the gabbroic enclave it seems that gabbroic enclave has exotic genesis. Gabbroic rocks fall into andesitic magma during magma passing upward.

The Masjeddgaghi Cu-Au deposit is located at the southeast of the Arasbaran zone, NW Iran, to the south of Lesser Caucasus. Mineralization in Masjeddaghi is associated with an Eocene dioritic subvolcanic pluton intruded into volcanic and sedimentary rocks. The Masjeddaghi intrusive is high K, calc alkaline- and meta-aluminous, and formed in post magmatism stage, in an island arc setting. Hydrothermal alteration is distinguished by potassic core marked by secondary biotite, and K-spar that grades outward into a chlorite-rich propylitic halo The ore mineral include chalcopyrite, associated with minor chalcocite, bornite, tetrahedrite, and trace amounts of molybdenite. Pyrite and magnetite are common associate. The Masjeddaghi deposit is elliptical in view, 500m in 400 in diameter, and mineralization has been traced for several hundred meters from surface exposures.. 40Ar/39Ar geochronology on secondary biotite from the potassic alteration zone indicates that mineralization, and accordingly the emplacement and crystallization of the Masjeddaghi porphyritic intrusion occurred 54.07 ± 0.53 Ma ago. Masjeddaghi ore deposit shows geology, mineralization and alteration characteristics similar to island arc porphyry type systems.

The study area is located in the Central Iran Zone, in the view of tectonic subdivisions of Iranian terrains. The main outcropping rock types are metabasites and amphibolites having Precambrian age. The amphibolites have been classified as Ep-amphibolite, normal amphibolite, Grt-amphibolite and Grt-Cpx amphibolite, considering characteristic mineral assemblages. The main textures are granoblastic and porphyrogranobastic. Mineral chemistry of Grt-Cpx amphibolites have been investigated in this contribution. The results have been used to estimate metamorphic P-T conditions. The compositions of amphiboles are pargasite and hornblende. Clinopyroxne is diopside. Plagioclases are rich in An content (An73.50-95.90) and Ab content is low (Ab3.90-24.70). Garnet have compositions as Alm (%45.90-%59.10)¡ Prp (%5.6-%16.1)¡ Sps (%10.90-%23.50)¡ GAU (%13.20-%23.70) . Garnet composition is non-uniform as increasing of Fe and Mg contents where Mn and Ca contents are decreased from the core to the rim. The peak metamorphic T-P obtained as 670 oC to 705 oC at 8.5 Kbar respectively. The estimated pressure is consistent with the depth of ~25Km correspending to the lower crustal condition. The recorded mid P-T conditions of Grt-Cpx ampgibolites belonge to Barrovian type regional metamorphism. On the basis of geological and petrological studies from the SE Qarehaghaj and the analogies with comparable rocks from adjucent Precambrian terrains, it seems that the Pan-African Orogeny is the phase causing metamorphism and consolidation of the basement rocks. The Precambrian metabasites and amphibolites have been probably formed in this regard. The subsequent mid P-T metamorphism of the metabasites under upper amphibolite facies (Barrovian type metamorphism) have been most likely recorded related to continental collision between the Arabian plate and the Central Iranian micocontinent correspending to the Alpian Orogeny during Cenozoic.

The young basalts in East Azerbaijan are placed in West Alborz – Azerbaijan zone. Volcanic activities have extended from the Pliocene to the Quaternary by eruption from fracture systems and faults. Rocks under study are olivine-basalt and trachybasalts. The main minerals are olivine, pyroxene, plagioclase set in glassy or microcrystalline matrix and olivine are present as phenocryst. The textures in the studied rocks are mainly hyaloporphyric, hyalomicrolitic and porphyritic. Trace elements and rare earth elements on spider diagrams have high LREE/HREE ratio. Rare earth elements on diagram display negative slope indicating alkaline nature for the basalts under study. As it may be observed, on tectonic diagrams, the Marand basalts are placed on Island Arc basalt (IAB) field, whereas the Ahar, Heris, Kalaibar and Miyaneh basalts are classified as Ocean Island Basalts (OIB) and finally the basalts of Sohrol area are plotted on continental rift Basalt (CRB) field. The Marand and Sohrol basalts were likely originated from lithospheric - astenospheric mantle with 2 to 5 % partial melting whereas, the Ahar, Heris and Kalaibar basalts having same source experienced 1-2% partial melting rate and the Miyaneh basalts possibly produced from lithospheric mantle with 10-20% partial melting rate pointing to shallow depth of mantle and the higher rate of melting. Based on tectonic setting diagrams, all the rocks studied are plotted in post collisional environments.

Understanding the behavior of the groundwater system and forecasting it’s fluctuations in the future are essential to achieve comprehensive and sustainable management of groundwater resources. The purpose of this study was clustering of Maragheh Aquifer’s observation wells and groundwater level prediction using Wavelet-Artificial Neural networks. Initially, 20 observation wells of Maragheh Aquifer with 15 years and more groundwater level records were clustered using hierarchical-WARD clustering method. Cluster with 6 homogenous subcluster and representative well of each subcluster were selected. Using wavelet, input time series noise were removed. Then groundwater level of representative wells were forecasted by Artificial Neural Networks. Results showed, considering of temperature time series data as input was confused Artificial Neural Networks and Wavelet-Artificial Neural Networks. On results, taking 3 to 12 months consecutive time delay in input data decreased different between recorded and forecasted data. Minimum value of RMSE (0.03 m) and maximum value of (0.999) were in WNN. Mentioned values in ANN were 0.32 m and 0.885 (respectively). Based on the results of this research, de-noising of input data decreased difference between recorded and forecasted data as 11 cm averagely.

The study area is located about 30 km northwest of Maragheh in East Azerbaijan. The lamprophyric dyke intruded the Shemshak sedimentary rocks. Based on stratigraphic evidences, the age of dyke is probably Early Cimmerian. The principal minerals of the lamprophyric dyke consist of plagioclase (andesine -oligoclase), biotite (eastonite), phlogopite, olivine and clinopyroxene (diopside) with ocellar texture. The average chemical composition of clinopyroxene and plagioclase is En42.3, Wo46, Fs11.7 and Ab51.74, An30.92, Or17.34 respectively. According to the mineralogical and geochemical evidences, the studied lamprophyre samples are kersantite belonging to calc-alkaline lamprophyre.The plotted spider diagrams for the rock samples indicate the light rare-earth elements (LREE) and incompatible elements enrichment compared to heavy rare earth elements (HREE). The parent magma is probably generated from garnet lherzolite mantle with low rate partial melting. The studied lamprophyre dyke formed in intraplate and post collision environment which translocated possibly in basins and ruptures in related with fault systems.

The Curie point (approximately 580C for magnetite at atmosphere pressure) is the temperature at which spontaneous magnetization vanishes and magnetic minerals exhibit paramagnetic susceptibility. The depth at which temperature reaches the Curie point, is assumed to be the bottom of the magnetized bodies in the crust. Curie point temperature varies from region to region depending on the geology of the region and mineralogical content of the rocks. Therefore, one can normally expect shallow Curie Point Depths (CPD) at regions which have geothermal potential, young volcanism and thinned crust (Aydin and Oksum, 2010). The assessment of the variations of the Curie depth of an area can provide valuable information about the regional temperature distribution at depth and the concentration of subsurface geothermal energy (Tselentis, 1991).    There are two basic methods which have been used in the examination of the spectral properties of magnetic data to estimate the magnetic basement depth. The first is the method of Spector and Grant (1970) and the second is the method of Bhattacharyya and Leu (1975, 1977). Spector and Grant (1970) showed that the expectation value of the spectrum of an ensemble model was the same as the average depth to the top of an ensemble of the magnetized rectangular prism. The second method estimates the depth to the centroid of the body by using the interpretation of a single anomaly. This method is useful when no spectral peaks occur on the amplitude spectra (Li et al., 2010). Following this, a joint method was developed by Okubo et al. (1985) who combined and expanded the ideas of the methods to the purposes of geothermal exploration.    CPD estimation (Zb) is obtained in two steps as suggested by Okubo et al. (1985). First, the centroid depth (Z0) of the deepest magnetic source is estimated from the slope of the longest wavelength part of the spectrum divided by the wavenumber, where P(k) is the power density spectrum, k is the wavenumber, and A is a constant. Second, the average depth to the top boundary (Zt) of that distribution is estimated from the slope of the second longest wavelength spectral segment (Okubo et al., 1985), where B is a constant. The equation Zb = 2Z0 - Zt(Okubo et al., 1985) is used to estimate the depth to the bottom (Zb) of the inferred CPD from the centroid (Z0) and the top depth (Zt) estimated from the magnetic source for each sub-region.    The study area was divided into eleven overlapped blocks for the purpose of spectral analysis. Center of blocks are shown on the residual field map (Figure 3). Each block covers a square area of 140 km by 140 km. Power spectral analysis was conducted on the RTP values of each of the blocks by plotting the logarithm of spectral energies against the wavenumber. The CPD estimation procedure as suggested by Okubo et al. (1985) was carried out for the eleven blocks to obtain the Curie point depth for each block. Figure 5 shows Curie depth values and thermal springs of the study area. In this figure, Curie depth varies between 9.42 and 18.92 km. For the blocks of 3, 6 and 7, Curie point depth is significantly less than the other blocks, which could be due to the presence of high temperature hot springs in this area. According to the geological information and Curie point depth values, A, B, C and D area are recommended for more geothermal investigation.

The Astarghan copper-gold deposit is located about 50 km north of Tabriz, southeast of Kharvana, East-Azarbaidjan. The most important lithologic units in the area are a hypabyssal prophyritic granodioritic intrusive stock (Oligo-Miocene) and flysch-type sedimentry sequence consisting of limestone, limy sandstone and marl (Paleocene-Eocene). The plagioclases range in composition from oligoclase to andesine and K-feldspars are mainly orthoclase. Amphiboles are principally of calcic-type and vary in composition from magnesio-hastingsite to edenite. The stock is of I-type granites and meta-aluminous, belonging to high-k calc-alkaline to shoshonitic magma series, which are related to post-colission volcanic arcs. Intrusive body shows enrichment in elements such as La, Nd, Rb, U, Pb, Zr, Cs and P and depletion of Ce, Pr, Ta and Nb. LREEs relative to HREEs are also enriched. Electron probe micro-analyses of ore minerals proved the presence of native gold within sulfides (stibnite and tetrahedrite) and quartz veinlets. The highest gold content is within the structure of sulfosalts (tetrahedrite-tenantite) and low-temperature sulfides (stibnite). The presence of high values of gold-tracing elements such as Sb, Hg, Bi and As within the studied ores is in accordance with the studied geochemical halos of these elements in the area which, in turn, may indicate a low temperature for the formation of the ore minerals.

BLEGmethod is one ofmodern methodsusedfor goldgeochemicalexplorationstudies.Themethod has helped to locate many low grade gold deposits. The significant change of the method compared to common geochemical exploration methods is to use of large volumes ofsamples regardless of their sizeandlow densityof sampling.In order to evaluate the efficiency of the BLEG geochemical method with stream sediment method, 1:100000 SiahRud sheet was chosen in geological region of Azarbaijan in a district that geological map and geochemical exploration has already been carried out.The study area is 1850 km2, located in a mountainous area of northwest Iran in the Eastern-Azarbaijan province (NW of Ahar city).The rock units of the area consist mainly of the Upper Cretaceous limestone and flysch complex, Oligocene intrusive bodies and Eocene volcanic-sedimentary rocks. The Oligocene intrusive bodies are the most important igneous unit in the area.In this project, 168 BLEG samples and 103 stream sediment samples (silt samples) were prepared and studied. The range gold values in BLEG samples are from 0.1 to20 ppb, and in the stream sediment samples from 3 to459 ppb.The results ofsampling and analysis present four districts with high anomalous degrees: 1) Anigh-GharehChilar district, 2) Namnegh district, 3) Eshtobin district, and 4) Andrian or MiveRud district. Analysis ofthe stream sedimentsamplesrepresentshigh value of Cu andAu. Correlation of the elements in stream sediments taken from the Anigh-GharehChilar district represents high correlation of gold with arsenic, copper and leads elements. Copper also shows a high correlation with molybdenum, which is in accordance with mineralization of this area.

Gharahchaman is located inthe Urumieh Dokhtar zone in east Azerbaijan. The area is mostly comprises of intermediate to acidic intrusive and extrusive, Oligocene igneous rocks along with younger sedimentary units. The regional geochemical exploration program with the aim of delineating potential zones in the area were attempted by collecting 394 stream sediment samples, which analyzed for 44 elements. Most of the exploration programs are routinely based on the positive anomalies (+ve) detection and the negative halos (-ve) are rarely considered. The depletion of some pathfinder elements may be related to ore mineralization in the area. Therefore (-ve) halos also can be significant in regional exploration. Conventionally, negative anomalous threshold values have been calculated in the same way as positive one, which causes drawbacks and hinder their application. In this paper an attempt were made to construct integrated models of (-ve) and (+ve) potential maps for detecting optimized geochemical pattern. It can be deduced from this study that the detected significant (-ve) halos, mostly are influenced by syngenetic processes and some are also related to ore bearing solutions. Detecting (-ve) halos of elements such as Sc, Sr, and Na in a particular pattern and in vicinity of (+ve) halos like Au, Cu, Pb, U, Zn are related to base metal mineralization and other important elements in the region. On the basis of combined distribution pattern of elements three models of geochemical anomalies are accompanied each other;1) Overlapping of multi-element (-ve) and (+ve) anomalies like (Rb, Sr); 2) Peripheral regional multi element (-ve) anomalies that surround (+ve) anomalies like (-ve) halo of Sc around (+ve) halos of Ce, Rb/K and (–ve) halo of Sr with Ba/Sr ratio, felsic and chloritic zones in the area; 3) Discriminated Indices model of (-ve) and (+ve) halos of (Mo-Sr), (U-Sr), (Cu-Sr).This indicates that the combined study of (+ve) and (-ve) halos in regional geochemical exploration studies can be more significant in detecting hidden ore deposits. The distribution pattern of felsic and chloritic additive composite alteration zones match with Model2, which mutually correspond to (+ve) and (-ve) anomalies of Au and Sr respectively. Ultimately the results revealed deficiency in study of only positively concentration of elements along with faulted zones, whereas the present study emphasis that modeling corresponding of (-ve) and (+ve) halos along with results obtained from composite additive indices confirms NW-SE concentration of ore mineralization in the area.

The occurrence of uranium anomalies associated with secondary Cu mineralization (malachite) at some parts of the Razgah metaluminous -peralkaline stock situated at the northeast of Sarab caused it to be a priority of Atomic Energy Organization of Iran (AEOI) to inspect the intrusion for likely uranium mineralization. Hence the current study, which is supervised by AEOI, was carried out to investigate the U mineralization potential of the stock by applying the mineralogical, petrological and geochemical studies. A fractionation trend is inferred from variations in rock compositions stretching from nepheline-bearing monzodiorite to nepheline monzosyenite, pseudoleucite monzosyenite andnepheline syenite. Consideration of geochemical features of fresh rocks of the stock and its associated dikes with emphasis on geochemical behavior of U and REEs during magmatic fractionation revealed that apatite has played a prominent role in controlling concentrations of REEs, U, and Th, in addition to zircon, which played a considerable role in accommodating HREEs, U, Th and HFSEs (Ti, Ta, Nb, Hf, Zr) in more differentiated rocks.Nepheline syenite rocks of peralkaline composition,s which are considered to be the most differentiated have low contents of HFSEs, U (up to 21 ppm), Th (up to 56 ppm) and REEs compared to average nepheline syenites but are relatively more enriched in these elements than less differentiated rocks of the stock. Most of the rocks possess negative Eu anomalies (Eu/Eu*≤1) and differentiated nepheline syenites have strong negative Eu anomalies. Abundance of ilmenite and magnetite and lack of amphibole in rocks suggests the parental magma had a reducing nature and meagre contents of volatile components, which along with metaluminous character and prepondarence of apatite in rocks have rendered the magma incapable of enriching U. Minor amounts of hydrothermal fluids released from some parts of the stock led to leaching of U from hosting minerals (apatite and zircon) and resulted in weak hypogene mineralization of U and Cu. Later supergene leaching process affected the weak primary mineralization and upgraded U tenors concurrent with formation of secondary Cu carbonate minerals. Due to thin and limited extention of these enrichment sites, they are not economically viable for uranium extraction; consequently, this area does not suggest for semi-detailed and detailed exploration program for uranium by AEOI.

Investigation on the causes of the water escape from Arbatan Dam is the main objective of this paper. The dam is located 50 km of North-East Tabriz in Azerbaijan-e-Sharghi province. The maximum capacity of the dam reservoir is about 27 millions m3 and is feeding by an artificial channel with 26 km length from Talkh-e-Roud River. The dam is constructed in 2005 and it is dewatered four years later due to water escaping. Geothechnial and field investigations show that Gypsifeerous marls with intercalations of Gypsum crystals are the main lithology of the site. A Salt layer has also been recognized in 35m under the reservoir. It seems the water has been reached to salt layer by dissolution of gypsum layers. The salt layer dissolution has been caused the underground channels and sinkholes, consequently. Roof falling of the underground channels caused the ground subsidence and the dam axis has broken. The same tendency of sinkholes and land subsidence with layers strike in the study area confirms the obtained result.

Nepheline syenite intrusive of Kaleybar is located in South and West of the Kaleybar city in easternAzarbayjan province. This zoned intrusive complex is formed by penetration of two separated silica undersaturated and saturatated magmatic phases with Oligocene-Miocene ages. Undersaturated rocks are composed of alkali pyroxenite, mela alkali-gabbro to nepheline gabbro diorte, nepheline syenite and nepheline sodalite syenite dikes. Silica saturated rocks is consist of a quartz monzonitic stock, which has penetrated in the center of nepheline syenite intrusive and related quartz syenite - micro syenite dikes. Undersaturated phase has potassic alkaline affinity and nepheline syenites are miaskitic Malignite. In contrast, silica saturated rocks belong to high-K calc-alkaline to shoshonitic magma. Field observation, petrographical and geochemical studies, indicates that undersaturated rocks are comagmatic and crystal fractionation, accumulation and low density minerals floatation processes play significant role in their magmatic evolution. High enrichment of rare elements especially LREE and LILE compare to variable depletion of HREE and HFSE are infer a basanitic parental magma generated from a previously subduction-metasomatised lithospheric mantle source. Silica saturated magma of Kaleybar was probably resulted form the lower crust Partial melting and geochemical similarities resulted from partial melting of lower crust and its geochemical similarities with undersaturated parts is due to magma mixing and contamination. Repeatedly injection of alkaline and calc-alkaline magmas could be occurred in a post collision setting after Eocene in Azerbaijan region.