GEOSCIENCES
Year:2018 | Volume:27 | Issue:108 |Papers Count:34

The present study provides a detailed facies and depositional environment analyses of the Neogene strata in the northern Dezful embayment, footwall of the Zagros Mountain Front fault. The Neogene strata in this area, including the Mishan, Aghajari, and Bakhtyari formations, constitute the thickest Zagros foreland succession, with more than 5 km of thickness. As these sediments were deposited synchronous with the main phase of the Zagros orogeny, they have recorded the history of deformation events. During the current study, 9 lithofacies have been identified on the basis of lithology, grain size, sedimentary structures, and bed geometry, which can be classified into three facies assemblages including: gravel dominated (Gm, Gp), sand dominated (Sh, St, Sp, Sr), and mud dominated (Fm, Fl). Furthermore, two major marine ichnofacies, the skolithos and the Cruziana ichonafacies, have been identified at the base of the Aghajari Formation. As the results indicated, the vertical stacking of facies represents an overall shallowing-upward succession that was deposited in marginal marine (Mishan), siliciclastic shoreline (base of Aghajari), meandering river (top of Aghajari) and braided river (Bakhtyari) depositional environments, from base to top respectively. Considering eustatic sea-level fluctuations in the deposition period (13 to 3 Ma), these results propose that evolution of the Neogene sedimentary basin in the North Dezful likely controlled by tectonic folding and faulting.

The study area is located at N to NW of Rabor city in the Kerman province within the Uromieh-Dokhtar Magmatic Belt (UDMB). Most of the rocks in this area include diorite, granodiorite and granite, which are exposed in volcanic sequences and cut them. Based on the geochemical features, all of rocks classify in two groups: (1) some granitoid rocks show adakitic affinity with high SiO2 (61. 49– 66. 78 wt. %), Al2O3 (15. 72– 17. 74 wt. %), Sr (374– 602 ppm), Sr/Y (34– 53), (La/Yb)N (8. 35– 16. 88) and low Y values. (2) another rock group is granitiods with typical calc-alkaline characteristics with distinct features different from adakitic types such as: SiO2 (63. 07– 72. 32 wt. %), lower Sr/Y (3. 8– 13. 2) ratio and higher Y (21. 7– 31. 6 ppm) and Yb (2. 29– 3. 26 ppm) contents, and the lowest Sr (119– 297 ppm) and (La/Yb)N (3. 02– 11. 13) values relative to adakitic groups, with obvious negative Eu [(Eu/Eu*)N= (ave. 0. 49)] anomalies. The adakitic rocks most probably originated from thickened mafic lower crust (garnet amphibolite) with garnet+ rutile ± plagioclase as residual minerals in the source, corresponding to depths of >50 km, and calc-alkaline rocks were probably generated at shallow depth than adakitic groups in mid-lower crust (dominant amphibolite) correlating to depths of <50 km. Study of 143Nd/144Nd (0. 512686– 0. 512776), ε Nd= +1. 44 to +3. 19 and 87Sr/86Sr (0. 705195– 0. 704871) isotopic ratios revealed a mantle lithospheric origin for the granitoid rocks. Positive relationship between SiO2 variations with isotopic ratios shows effect of crust assimilation in evolution of primary magma. Finally, we propose based on the geological, geochemical and isotopic data, that calc-alkaline and adakitic magmatism in the SE of UDMB generated by partial melting of the upper mantle and subsequent mixing with lowermid continental crust due to subduction of Arabian ocean crust under the Central Iran micro-plate during the Oligocene-Miocene.

Barremian sediments of the Garau Formation have been investigated at the southwest of the Kabir-kuh anticline (Qaleh-Darreh section) with regard to calcareous nannofossils. According to the presence of index calcareous nannofossils, NC5 biozone and NC5c, NC5d and NC5e subzones of Roth (1978) and CC5-CC7 biozones of Sissingh (1977) have been identified. At the studied interval, warm water taxa like Cyclagelosphaera margerelii, Diazomatolithus lehmanii, Lithraphidites carniolensis, Micrantholithus spp., Nannoconus spp., Rhagodiscus asper and Watznaueria spp. have been recorded along with cool water taxa such as Biscutum constans, Helenea chiastia and Zeugrhabdotus embergeri. The abundance of warm water taxa is higher than cool water taxa and a reverse trend can be observed. Regarding cool and warm water taxa three warming phases and two cooling phases are identified which includes the warming event of early Early Barremian, cooling event of Early Barremian, warming event of Mid-Barremian, cooling event of late Barremian and warming event of Barremian-Aptian boundary. It must be mentioned that these data are in accord with those reported from other parts of the world in the tethyan (e. g., Italy) and the boreal realms (e. g., NW Germany and NE England).

The Faraghun Mountains are located in the southeastern part of the Zagros orogen. Early Ordovician-Permian rock units are deepest stratigraphic units exposed in the central part of the Faraghun Mountains. High Zagros Fault (HZF) is the main structural feature bordering the southern flank of these mountains. Here we combine detailed mapping, field-based structural kinematic analysis and cross-sections to reconstruct the structural evolution of the Faraghun Mountains. Our new structural and stratigraphic analysis document three kinematically and geometrically different western, central and eastern segments for the HZF in the Faraghun Mountains. Both the eastern and western segments of the HZF dip to the north and are connected by the central segment that which is dippingto the south. Late Paleozoic successions have been exposed in the hangingwall of the Central High Zagros Fault segment in a pop-up geometry, and the Faraghun and Narangan faults have been formed in its footwall. Structural data indicates a right-lateral strike-slip mechanism with reverse component for the western and eastern segments, and reverse with right-lateral strike-slip component for the central segmenst of the HZF. Stratigraphic records document prominent variation in the late Cretaceous sequences including Gurpi Formation in the hangingwall and footwall of the HZF in the Faraghun Mountains. Greater thickness and basal conglomeratic nature of Gurpi Formation in the hangingwall of the HZF with respect to its footwall might reflect normal kinematics of the HZF and a high-energy depositional environment in its hangingwall during the deposition of the Gurpi Formation. All the stratigraphic and structural evidence represent post late Cretaceous compression accompanied by late Cenozoic right-lateral transpression in the Faraghun Mountains of SE Zagros.

The Upper Devonian Jeirud Formation provenance was investigated by means of petrography, modal analysis and heavy minerals assemblage, and mudstones major and minor elements geochemistry. Modal analysis results suggested recycled orogens, craton interior and passive margins as tectonic settings of Jeirud formation deposits. Based on modal analysis results, the Jeirud Formation siliciclastics were resulted from weathered plutonic and metamorphic rocks under humid to sub-humid climate conditions. Heavy minerals assemblages also, suggest a mixture of basic to acidic igneous rocks and recycling of older sedimentary rocks as the provenance. Althogh based on high compositional maturity of Jeirud sandstones, weathering under humid to sub-humid climatic conditions is most likely, but several evidences such as existence of dolocrete and rhizolith, unstable heavy minerals (Pyroxene, Amphibole, Apatite), existence of Polygorskite clay mineral and lack of coal deposits are inconsistent with humid to subhumid climate conditions and suggest semi-arid to arid climatic conditions. Accordingly, relatively high maturity of the Jeirud sandstones can be related to recycling, low gradient, long distance transporting, and high energy conditions in coastal environment. Combinig of major element based plots and trace element based plots such as La-th-sc ternary plot and La/Th versus Hf plot is suggesting a mixture of felsic, mafic and quartz-bearing sedimentary rocks (Recycled) as the source rocks for the Jeirud Formation siliciclastic deposits. An integration of modal analysis and heavy minerals results into the geochemical studies including Verma and Armstrong-Altrin Functional diagrams, indicate that, siliciclastic rocks of the formation, are resulted from weathering of acidic-intermediate to basic rocks of collisional tectonic provenances (recycled orogens). Investigations and comparison with previous studies, confirm that geochemical results and proportions of study area are consistent with those of old upper continental crust (OUC) typical of collisional tectonic settings. The CIA values of mudstones are indicative of moderate to intense weathering typical of humid to sub-humid climatic conditions, which are unreliable and inconsistent with heavy minerals results and field and petrographical evidences (dolocrete and rhizolith) due to effects of recycling.

The Alborz, as one of important seismotectonic provinces in Iran, has a great vulnerability from natural disasters, especially seismic risk point of view, because of the existence of Tehran megacity in its southern edge. The importance of this area has caused to the establishment of a relatively dense GPS network around it. In this study, earthquake focal mechanism data obtained from different resources, was used for stress tensor inversion in the Central Alborz. On the other hand, interpolation of the GPS vectors in rectangular grids and differentiation in the center of each grid cell was used for study of strain rate in this area. The results showed spatialvariations in principle axes of stress and in strain rate in different parts of the Central Alborz, which shows the geodynamic complexity of the study area. Finally, the angular differences between the maximum horizontal stress and compressive axis directions of strain rate were calculated in the location of the clusters of the earthquakes. These calculations showed that the extent of the strain partitioning in the middle parts of the mountain range, where strike-slip motions on Mosha and Firuzkuh faults are observed, has more significant effect on the current deformation processes in the Central Alborz. In contrast, in the northern parts of the range, where dominantly dip-slip motions on Khazar Thrust and North Alborz fault occur, deformation partitioning plays a minor role.

The studied area is located in the vicinity of Sherbit village, approximately 28 km to the northeast of Ahar (East Azerbaijan province). Quartz monzonite intrusive body is the host rock of hydrothermal tourmalines in this area. On the basis of their textural features, the tourmalines can be divided into four groups: 1) tourmaline veins, 2) massive tourmalines (quartz-tourmaline), 3) pore space filling tourmalines, and 4) tourmalinebreccia. Based on the petrographic studies and electron microprobe analysis, tourmalines of the Sherbit area include schorl-dravite types with more tendency towards dravite composition and are classified in alkaline group. Characteristics such as high Mg/Fe ratios, low Al amounts, fine scale zoning, content of fluorine, tendency towards outer side of alkali depletion-and de-protonation, and lack of negative correlation between Fe and Mg, are indicators of formation of the tourmalines in a hydrothermal condition. The trend of rare earth elements in tourmalines shows a very similar pattern to the quartz monzonite samples (host rock), in which a pattern of the depletion in HREEs relative to LREEs is visible. It can be concluded that REE concentrations and their patterns in different studied tourmaline rocks are substantially controlled by the host rock, with a minor role played by the boron-baring hydrothermal fluids causing boron metasomatism.

In the present study the Abderaz Formation ostracods were investigated. The thickness of the formation in this section is 385m, and consists of shale and marl together with three horizons of chalky limestone. Paleontological studies led to identification of 16 genera and 51 species of ostracods and differentiation of four biozones in this section. According to the ostracods and correlation with calcareous nannofossils in this section, an age of late Santonian to early late Campanian is quoted to the formation at this section. Presence of warm water index species and absence of cool water forms suggest warm surface waters. Also changes in depth and oxygen were concluded during depositional course of the formation.

The Badamu Formation with Middle-Upper Jurassic (late Toarcian-Early Bajocian) age introduced as the third the formation of Shemshak Group in the Central Iran that for facies studies and depositional environment, the Bolbolueih section in SE Kerman with a thickness 144m was selected and sampled. Facies analyses of the Badamu Formation led to identification of 16 lithofacies that were classified into four facies associations including carbonate, siliciclastic, hetrolithic carbonate-siliciclastic and oolithic ironstone. The important facies of the Badamu Formation in studied section is oolitic calcarenaite facies (La) that according to textural and structural features classified into six lithofacies (Lah, Lal, Lap, Lam, Lar and Lat). The sorted ooides in grainstone microfacies accompanied by structural evidences such as cross-bedding with bimodal to bipolar palaeocurents, hummocky and herringbone cross-beds, reactivation surfaces, wavy ripple marks and rain drop imprints reveal that this facies were deposited in shallow beach environment. Textural and structural characterizes in the associated facies (sandstone and hetrolitic fasies) such as high textural and compositional maturity and flaser bedding is consistent with this interpretation. Vertical and lateral accretions of the recognized facies show that the Badamu Formation successions have been deposited in a shoreface subenvironment in the beach and beach ridges model framework.

Northeastern part of Iran islocated in the Koppeh Dagh seismotectonic province. This province is part of the Alpine-Himalayan orogenic belt. In the last two decades, a number of earthquakes occurred in this region. Therefore, investigating and relocating these earthquakes with adequate precise play a great role in seismicity research of the study area. Adequate crustal structure velocity has a key role in relocating the earthquakes. Since the earthquakes in this region are shallow earthquakes, the upper part of crustal structure can be acquired. So in this study, Mashhad and Quchan seismological networks data were used to determine the crustal structure velocity. In order to determine the velocity structure, Vp/Vs was first determined using the methods of Wadati and travel time of1. 72. Then by applying various filters and selection of several earthquakes 1D velocity structure of the arrival times was determined. Results reveal two velocity discontinuities approximately at 4 and 14 km depths. The resulting model consists of a 4-km-thick layer with VP = 5. 9 kms− 1 overlying a 10-km-thick layer with VP = 6. 17 kms− 1. Then the initial 1D velocity model was used to determine the three-dimensional velocity structure using LOTOS code. The results show significant changes in the vicinity of Mashhad. Two zones with higher velocity are observed in the north and south of Mashhad due to Kashaf Roud and Binaloud Faults. In the north of Mashhad, a change in velocity is observed, which might be due to the Tous fault. In the south of Mashhad, a sharp velocity discontinuity at the depth of 4 km is probably due to an alluvium cover above a bedrock of varying thickness. Also, the tomography results indicate that the area of Shandiz fault system in the south of Mashhad is associated with a lower velocity zone compared to its adjacent areas.

The Namegh area is located in northeastern Kashmar, Khorasan Razavi province, and central part of the Khaf-Kashmar-Bardaskan magmatic belt. The area is covered by Eocene volcanic rocks having andesite to rhyolite compositions, which are intruded by subvolcanic intrusions having monzonite, monzodiorite, and diorite compositions. All theseunits are affected by well development alteration, which are silicifiedsericitic, moderate argillic, and propylitic alteration zones. Mineralization is occurred as stockworck and disseminated. The primary minerals include chalcopyrite, pyrite, magnetite, and gold. The secondary minerals aregoethite, hematite, malachite, and azurite. High anomaly of Cu (up to 1%) and Au (up to 12 ppm) are correlated with strong silicified-sericitic alteration. Based on fluid inclusion studies, formation temperature of mineralization was between 404 to 551 º C and it occurred by NaCl-, and CaCl2-bearing fluid with 16 to 23 wt. % NaCl equivalent salinity. Decrease of temperature and HCl activity during boiling and decrease of temperature due to mixing of magmatic and meteoric fluids could be the most important factors for mineralization. Evidence of tectonic setting, lithology, development and types of alteration, mineralization form and limited outcrops, types of ore minerals, geochemical anomalies, types of fluid inclusions, and temperature and salinity of fluid indicate that the mineralization of Namegh is probably upper level of a porphyry Cu-Au deposit. The Khaf-Kashmar-Bardaskan belt can be one of the most important porphyry deposits metallogenic zones of Iran due to tectonic setting and magmatic-mineralization evidence, which needs detailed exploration in the future.

Jahrom Formation is dominated by gray thick bedded limestones that mainly consist foraminifera. Two stratigraphic sections, (Saldoran and Dasht-Zari) were selected for this research and the thickness of this formation is reached to 176. 5 and 200 m respectively. These sections are located in west of Shahr-e-Kord, (High Zagros). In both sections, the Jahrom Formation unconformably overlies the upper part of the Gurpi Formation and conformably underlies the Pabdeh Formation. Based on microscope observations and fossil contents, eight microfacies are determined in four facies belts, that extend from tidal flat to deep open marine on a ramp environment. These facies contain: 1) Mudstone. 2) Rhaphydionina polymorphina wackestone. 3)Hyaline-porcelanouse faraminifera wackstone. 4) Red algae packstone. 5) Lare hyaline foraminifera wackestone 6) Red algae planktonic foraminifera wackestone. 7) Planktonic-small hyaline foraminifera wackestone. 8)Planktonic mudstone. Among these, only the two facies, Planktonic-small hyaline foraminifera wackestone and Red algae-planktonic foraminifera are not common between the two sections. Based on the foraminifera, an age of Early – Middle Eocene is quoted to the formation at this section.

In the past decade, several geophysical, geological and reservoir studies have been done on the Qom formation in the Yortesha field for injection and gas storage purposes. Qom formation in this field has a poor reservoir characteristic (low porosity and permeability); therefore the role of fractures for increasing permeability and improving reservoir quality is very important. In the current study, fracture concentration and strike patterns of the Qom and Upper Red formations as the carbonate reservoir and cap rock, respectively, have been investigated and compared in the Yortesha anticline and its adjacent anticlines (Davazdah Emam and Morreh) using surface and subsurface information. In order to achieve this goal, field data, remote sensing, and image log analysis have been used. Subsurface studies and interpretation of FMS and EMI image logs determined that fractures have also a secondary strike of NE-SW in addition to the major strike of NW-SE. Based on the FMS image log interpretation of well No. 2, three subsurface fracture sets have been identified with the strikes of N55E, N65E, and N15W. The EMI log of well No. 4 shows two dominant directions of fracture strikesalongN10E and S45E. Rose diagram plots of a total 1852 specified fractures in the outcropping parts of the Morreh and Davazdah Emam anticlines show four fracture sets with the strikes of N10E, N45E, N80E, and S45E.

In this study, for the first time stratigraphy and depositional history of the Routeh Formation have been evaluated in west of Zanjan (Agh-Bolagh section). These deposits with a thickness of 102m consist of limestone, dolomitic limestone with the less frequency of thinbedded calcareous shales. This sedimentary sequence with an unconformity overlies the quartz-bearing sandstones of Doroud Formation and is overlain by a laterite-bauxite horizon below the vermiculate limestone of Elika Formation. The main components of the Routeh Formation contain different kinds of algae, small benthic foraminifera and with a less frequency echinoderm and brachiopod debris. Based on field and laboratory studies eight sedimentary facies have been distinguished within the formation. These facies due to the different types of allochems, texture and fossil content display a shallow-water marine environment during deposition of the Routeh Formation located at Palaeotethys passive southern margin. The absence of re-sedimented deposits like: turbidites, presence of micrite at the most of facies, lack of continues reefal facies and gradual facies change indicate that the Routeh Formation possibly deposited in a ramp carbonate platform. Due to great diversity and abundance of algae and benthic foraminifera, this carbonate ramp is referred to as an “ algae and foram-dominated carbonate ramp system” . Field observations, facies analyses and sequence stratigraphy studies led to the identification of one-third order depositional sequence for the Routeh Formation. This depositional sequence separated by type-1 sequence boundaries at below with quartz-bearing sandstones of the Doroud Formation and at the top with the laterite-bauxite horizon between Routeh and Elika formations.

An important goal in mining exploration is the estimation of the depth and the thickness of the causative source. According to this simplification, several methods have been developed for interpreting magnetic field anomalies. In this article, the Hilbert transform has been used to calculate the depth and thickness of 3-D thin plate anomalies. The Hilbert-Fourier transform performs an important role in analytic signals. Since the total magnetic fields anomalies function has the characteristics necessary for an analytic function, i. e. its real and imaginary parts form a Hilbert transform pair, the function can be used to interpret networked data in terms of three-dimensional origins. The Hilbert transform does not change the amplitude of a function but shifts the phase by π /2 and-π /2 for positive and negative phase values, respectively. This paper uses a two-dimensional Hilbert transform and a 3-D analytic function to calculate the depth of a thin three-dimensional plate modeled based on the method of Talwani for noisy data and without noise data. The results show that the estimated depth values derived from the Hilbert transform method are associated with an error of less that 3% for data without noise, and an error of 8% for data of 15% noise. . This method was also tested on the real magnetic anomaly data from the Kheirabad iron mine located at 5 km NE of Golgohar, Sirjan, Iran. The results were compatible with the Euler method and with drilling information of the mine. The obtained depth is in good agreement with the actual depth, which confirms the application of the Hilbert transform for the interpretation of field data and estimation of magnetic anomalies depths.

The Sebandoon gold deposit is located 40 km north of the Bardaskan in the northern part of the Central Iran. The rock units exposed in the area consist of upper Cretaceous volcano-sedimentary sequences of trachyte-trachyandesite, andesibasalt, tuff and carbonaceous shale which intruded by post Eocene syenite-quartz monzonite subvolcanic intrusions and diabasic dikes. The main gold reservoir in the Sebandoon deposit has occurred in cone-shaped and mostly in the trachyte-trachyandesite lava with dimensions of 90×150 m in the surface which continue up to the depth of 70 m. The hydrothermal alterations occurred in the deposit area include silicic, sulphidic, partly argillic (supergen) and propylitic which two former contains most of the high grade gold ores. The main ore structures and textures in the deposit are vein-veinlets (stockwork) and breccia which consists of quartz, sulphide minerals and rare adularia. Primary ore mineral assemblages of the deposit are simple and consist of pyrite, sphalerite, chalcopyrite, bornite, galena, arsenopyrite and gold. Covellite, chalcocite and iron hydroxides are secondary minerals in the deposit. Gold grains with less of than 60 microns in size has been found as inclusion in pyrite and chalcopyrite, in sulfides rims and intergrowth with quartz. Fluid inclusion studies on ore-bearing quartz reveal that majority of primary inclusions are liquid-rich two-phase (LV). The studies indicate homogenization temperatures between 165 and 254° C and salinity between 0. 9 to 7. 8 wt% NaCl eq. Comparison of the main characteristics of the Sebandoon deposit with epithermal gold deposits reveals that the geology, alteration, ore mineralogy, geochemical characteristics and fluid inclusions of the Sebandoon gold deposit is similar to low to intermediate-sulphidation type epithermal deposits.

Permo-Triassic subsurface section at Lavan 3 Well in Lavan Gas Field exhibits a 85 m-thick succession of limy dolostone and dolomitic limestone bearing anhydrite in the upper Dalan Formation, as well as a 154 m-thick succession of limy dolostone and dolostone with anhydrite intercalations in Kangan Formation. In the present study, 116 species belonging to 55 foraminifera genera were identified which were divided into two biozones, namely Charliella altineri-Paraglobivalvulina mira-Dagmarita chanackchiensis Assemblage zone (Dzhulfian in age) and Claraia aurita-Spirorbis phlyctaena Assemblage zone (Anisian in age). Nine primary microfacies were identified in the upper Dalan Formation, while, 13 microfacies were detected in Kangan Formation, together with different sub-environments (sabkha, tidal flat, lagoon, submarine ridge, and open marine) which were found to be deposited in a shallow marine carbonate platform in the form of a homoclinal ramp. Based on microfacies changes, aggradational, progradational and retrogradational stacking patterns of deposits and by conformation with the Gama-ray log, these strata could be divided into a couple of third-order sedimentary sequences for the upper Dalan Formation, as well as a couple of third-orders for the Kangan Formation, including two system tracts (TST and HST). On a global scale, the findings are comparable to the upper part of the Absaroka supersequence.

The multifractal modelling is an effective approach for separation of geological and mineralized zones from the background. Following cases are addressed in this study; Concentration-Distance to Major Fault structures (C-DMF) fractal model and distribution of the known Fe indices/mines in the Bafgh area to distinguish the Fe mineralization based on their distance to basement faults, surface faults and master joints, using remote sensing information, airborne geophysics information and field surveys. Application of the C-DMF model for the classification of Fe mineralization in the Esfordi and Behabad 1: 100, 000 sheets reveals that the main Fe mineralizations have a strong correlation with their distance to the major and basement faults. Accordingly, the distances of Fe mineralization that has the grades upper than 55% in this area )43%≤ S≤ 60%), are lower than 1 km related to basement faults, while such distance for this threshold is 2344

Pyroclastic rocks in the Badam area (E-Mahabad, west Azarbaijan Province), are located at the most extreme northern part of the Sanandaj-Sirjan zone. Petrographic studies revealed that they are basanitic in composition and have porphyric and microlithic porphyric textures. Olivine and clinopyroxne occur as phenocrysts and clinopyroxene and nepheline as microliths. Opaque minerals and glass have occupied the space between different minerals. In classification diagram, they have basanitic composition. Geochemical features such as enrichment in LILE, high LREE concentrations and negative anomalies in Nb, Ta and Y, with positives anomalies in Ba, Pb and Th and enrichment in Th/Yb, all suggest that these rocks have mantle source that are enriched by melt/fluids from the metasomatized subducted oceanic slab. These features are inherited from mantle source and they are not caused by crustal contamination. Regarding MREE and HREE ratios, these basanites originated from 1 % partial melting of a garnet lherzolite source in the garnet stability field (85 Km). Melting trigger in this area is not clear, but old theories such as lithosphere delamination or slab break up are not applicable any more. There is three suggestions about melting in these are: 1) break up of hydrated phases by depth increase, 2) changing and turbulence in convection follows, 3) subduction and dehydration of Arabic passive margin.

The Dehsheikh Ultramafic-Mafic Complex (DUMC), as a portion of the Esfandagheh-Faryab ophiolitic melange belt, accommodates several chromitite ore deposits, but their emplacement and relation to the regional structures remain ambiguous due to structural complexities. The Dehsheikh Ultramafic Massif is composed of harzburgites, dunites, chromitites, pyroxenites, and lherzolites. The chromitite ores, embedded in a dunitic host rock, are concentrated in the central part of the massif in the active Bozorg mine and also abandoned Ajdari and Konar mines. According to the results, the DUMC has experienced three deformational phases of D1-D3. The high-T transtenssional D1 deformation is recognized by injection of the pyroxenitic dykes (Di1), development of the dextral ductile shear zones (Dsz1) and rootless folds (F1) in the dunite-chromitites sequences. These evidences could demonstrate ascending of the Dehsheikh mantle diapir in the upper mantle during the D1 deformation. The D2 dextral transpressional deformation is characterized by formation of the conjugate F1b right-lateral strike slip faults (with reverse component) and F1a thrusts and associated V1 magnesite veins. The D2 structures developed along with emplacement of the DUMC under the prevalent Zagros oblique reverse faulting in the ophiolitic mé lange belt. Finally, the D3 was accompanied by conjugate F2a right-lateral strike slip faults (with normal component) and F2b normal faults, associated with development of the V2 magnesite veins under the local transtenssional regime along the Zagros fault. The F1 folds and F1-F2a, b faults structurally controlled deformation and emplacement of the chromitite ore deposits.

The Attary Fault is an oblique fault with a mapped length of ~20 km. It is concealed by Quaternary deposits both northeastward and southwestward. However, there is a fault in the north of Kavir-e-Chah Jam that can be considered as the northeast continuation of the Attary Fault in this area. In addition, satellite imagery reveals that the Mayamey Fault System extends southwestward into north of the Kavir-e-Chah Jam. Therefore, the Attary Fault may join the Mayamey Fault System in the north of Kavir-e-Chah Jam and hence reach a length of ~127km, considering the concealed parts. There is another major fault with maximum reported uplift of 4km, called the Peyghambaran Fault, to the northwest of the Attary Fault. To the west, the Peyghambaran Fault is linked to the Semnan Fault. The connection of the Attary Fault to the Peyghambaran Fault, Semnan Fault and Mayamey Fault System leads to creation of a greater fault system that could have served as the boundary between Alborz and Central Iran, despite the fact that the Attary Fault does not represent significant uplift and mostly cuts the Eocene volcanics. Additionally, since the Attary fault steeply dips to SSE (60-75◦ ), the so-called “ positive flower structure” which is widely regarded as the general framework for the Central Alborz has not formed in this part of the range. Our study also shows that a left-lateral motion has been initiated on the Attary Fault following the westward motion of the south Caspian basin in the Late Cenozoic.

Amphiboles in olivine-bearing hornblende-gabbros from NW of Salmas were crystallized in various textures including oikocryst and interstitial textures in the matrix, outer part of reaction rims around olivine, and at the rim and cleavages of clinopyroxene. On the basis of petrographical and textural studies, amphiboles were formed later than the other minerals in the olivine-bearing hornblende-gabbros. The REE and trace element composition of amphiboles from two different textures including interstitial and matrix amphiboles (group one) and amphiboles after clinopyroxenes (group two), indicate that the studied amphiboles were formed by either crystallization of interstitial melt/fluid or interaction of interstitial melt/fluid with early crystalized minerals such as clinopyroxene and plagioclase. Hence, according to the textural and mineralogical data and trace element composition of amphiboles, olivine-bearing hornblende-gabbros were crystallized at least at two stages. The first stage include fractional crystallization and formation of olivine, clinopyroxene and plagioclase and the second stage was interaction of the relict melt/fluid with early crystalized minerals, specially clinopyroxene and plagioclase and formation of amphibole.

The Ab-Bagh Zn-Pb deposit is located at the southeastern part of the Malayer-Esfahan metallogenic belt. This deposit is hosted by Upper Jurassic-Lower Cretaceous sedimentary sequence. Zinc and lead mineralization occurred within two horizons. The ore horizon 1 is hosted by Late Jurassic-Early Cretaceous black shale and siltstone. The ore body displays a wedge-like shape and is located close to syn-sedimentary fault. The ore horizon 2 occurs in lower Cretaceous carbonates and includes massive ore, concordant with the host rock layering; Syn-sedimentary faults, half-graben basins and related anoxic environments, had an important role in formation of SEDEX-type Zn-Pb mineralization in the Ab-Bagh and deposition of sulfides. Sedimentary debris flows and syn-sedimentary braccia within host rocks of the Ab-Bagh deposit suggests activity of normal faulting simultaneously with sedimentation of host rock and consequently development of half-graben structures. Formation of half-graben structures is one of the most important factors of redox condition of ore forming environment. This structures led to development of deeper zones within the basin, where anoxic condition were occurred. Trace and rare earth elements geochemistry of host rocks, size of pyrite framboids and presence of organic matter in the host rocks, represent anoxic to euxinic paleo-redox condition of this basin, which is caused by microbial activities and depth of the basin, associated with normal syn-sedimentary fault. Comparison of syn-sedimentary normal faulting and anoxic formation environment of the Ab-Bagh deposit with other SEDEX deposit of Iran, indicates similarity of their formational environment.

Qareh-Ziaeddin plain is located in the West Azarbaijan province, Northwest of Iran. The aim of this study is to investigate the effective factors and processes on the groundwater chemical quality of Qareh-Ziaeddin plain. For this purpose, 20 water samples were collected from groundwater resources in November 2016 and the concentration of the major ions, nitrate and silica was measured. Also, the pH and electrical conductivity of the samples were measured in the field. In this study, different bivariate and hydrochemical diagrams, chloro-alkaline index, saturation index and inverse modeling were used to achieve the mentioned goal. The results of the bivariate diagrams show that the saltwater intrusion from irrigation return flows, cation exchange, weathering and dissolution of rock minerals specially carbonates, silicates, gypsum and halite, and evaporation process, in a small amount, are the effective factors on the chemical quality of the groundwater in the study area. The calculated Chloro-alkaline indices indicate that these indices are negative in all samples, which reveal the normal ion exchange. The water samples are super-saturated with regards to the carbonate and quartz minerals, whereas are under-saturated with respect to the sulfate and halite minerals. The results of inverse geochemical modeling confirm weathering and dissolution of the carbonate, sulfate and halite minerals and ion exchange in different parts of the aquifer.

The Gazestan magnetite-apatite deposit is hosted within an upper Proterozoic-lower Cambrian volcanic-sedimentary sequence, known as Rizu series, in the Bafq district, Central Iran. The Gazestan deposit occurred in intensely altered felsic-intermediate subvolcanic and volcanic host rocks. Field observations, drill core logging, petrographic studies, as well as geochemical and XRD data are indicative of differences in alterations assemblages and temporal/spatial distribution of the alteration products, compared to other iron oxide-apatite deposits in the Bafq district. Unlike many other Bafq district iron deposits, sodic alteration is only locally developed. Similarly, Ca+Fe or actinolitic alteration is poorly developed in Gazestan. Chloritic and sericitic alterations are most closely associated with ore formation in Gazestan. Chlorite commonly associated with magnetite, quartz and calcite in the altered host rocks. The chemical composition of chlorite falls in pycnochlorite and clinochlore fields. Calculated temperature for chlorite formation varies between 324-236 º C. Sericite occurred both as a proximal alteration in ore zones, and as a distal alteration product in the volcanic and subvolcanic host rocks. Calcic-iron alteration is poorly developed in Gazestan. Potassic alteration marked by development of K-as well as biotite is only locally developed in Gazestan. Boron metasomatism occurs as quartz-tourmaline bands and disseminated grains in altered rocks. The scarcity and local nature of sodic (albitic) and calcic-iron (actinolitic) alterations, and the widespread and proximal chlorite alteration suggest that, compared to most other iron deposits of the Bafq district, Gazestan formed at relatively lower temperatures and possibly shallower depths.

The Gash metamorphic complex is situated at the west of Rasht city. Gasht-e-Rodkhan metamorphic rocks are considered as a part of this metamorphic complex. Metapelites (schist, gneiss and migmatite) are the most important lithological unit of the Gasht-e-Rodkhan area. Index minerals consist of staurolite, garnet, sillimanite and kyanite. The main rock forming minerals of muscovite-free melanosome of migmatites are sillimanite and biotite. There is garnet in some melanosome as well. Quartz, K-feldspar and plagioclase are the rock forming minerals of leucosome. Tourmaline, garnet, muscovite and sillimanite are accessory minerals. Average pressure and temperature calculated by Thermocalc software and conventional thermobarometers for schist, gneiss and migmatite samples are 8. 6 Kb, 630° C; 6. 7 Kb, 650° C and 6. 3 Kb, 720° C respectively. Mineralogical parageneses and geothermal gradient resulted from thermobarometry calculations of the Gasht-e-Rodkhan metapelites are compatible with metamorphic Barrovian gradient or orogenic type. Gash complex probably represents metamorphic rocks of medium crustal depth of a collisional tectonic setting between Alborz block and Turan plate. Partial melting of metapelites and generation of associated leucogranites have taken place as a consequence of muscovite dehydration melting.

There are different methods to improve the technical characteristic of problematic soils. Stabilizing with lime and reinforcing by high tensile strength elements are among the improvement techniques. . The use of geosynthetics to improve the engineering properties of various types of soil is well accepted now. Most of the studies have been limited to coarse-grained soils and few studies has been done on the feasibility of geosynthetic reinforcement on cohesive soils. Due to the positive effects of adding lime to fine-grained soils and their reinforcement by geosynthetic, concurrent effects of these methods can develop the usage of fine-grained soils. In the current research, clay samples have been stabilized with 0, 2, 4 and 6 % of lime and reinforced with geosynthetic (geotextile and geogrid) and cured for 1 and 7 days and then subjected to direct shear test. To investigate the soil-geosynthetic interface parameters and reinforcement efficiency, the direct shear tests were done on reinforced samples with geotextile and two groups of reinforced samples with and without transverse members of geogrids. The test results reveal that stabilization with lime increases shear strength and it is also increased with curing time. The shear strength of reinforced samples is higher than that of unreinforced samples, and under the same normal stress the shear resistance of the soil reinforced by geogrid is higher than of that reinforced by geotextile. Under the same curing time, the highest shear strength and reinforcement efficiency is achieved in samples reinforced and stabilized with 4% of lime and they are also increased with increasing curing duration.

The geothermal field at the south of Mount Sabalan is a part of the geothermal system of the Sabalan volcano region wherein manifestations of young volcanic activities including hot springs and surficial steams are observable. The surficial hydrothermal fluids in this area show maximum temperature of 77° C, pH range of 6. 4-7. 4, and maximum TDS values of 7006 mg/l. Generally, these waters are divided compositionally into two groups. The first are mainly Na-Cl waters while the second are chiefly Ca-Na-HCO3 waters. The rare and heavy elements in these fluids are principally boron, lithium, rubidium, cesium, arsenic, and mercury whose maximum abundances are 33511, 14265, 3418, 10366, and 5 ppb, respectively. Considering the lithologic units in the area, vast hydrothermal fluid activities, and wide-spread alteration zones, boron-bearing minerals were regarded to be as the major sources of this element, which was leached and transported by geothermal fluids. Boron concentration in these fluids is controlled in part by fixation in clay minerals. Further considerations in geochemical behavior of the rare and heavy elements in this geothermal field demonstrated that lithium and rubidium were absorbed by quartz and clay minerals, respectively at temperatures <300° C, and also Cl-ion played a main role for transportation of mercury. Although the concentration values of B, Hg, As, and Li in the geothermal fluids of the studied area are not high enough to warrant the potential economic mineralization for these elements, the presence of these elements in these hot waters was recognized to be very consequential from two environmental respects; firstly because these geothermal waters are being directly used for swimming and bathing in the area, and secondly they may act as hazardous pollutant sources when mixed with the underground and drinking waters.