somaye kazemi koohbanani; seyed jamal sheikh zakariai; mohammad hashem emami; Rahim Dabiri
Abstract
KoheSiah volcanic complex is in north east of Qorveh in the Kurdistan province and in Sanandaj-Sirjan zone.The age of the studied region rocks are related to the quaternary time. Set volcanic cone with a crater that has been identified as unspecified and are an average height of 2157 meters above sea ...
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KoheSiah volcanic complex is in north east of Qorveh in the Kurdistan province and in Sanandaj-Sirjan zone.The age of the studied region rocks are related to the quaternary time. Set volcanic cone with a crater that has been identified as unspecified and are an average height of 2157 meters above sea level. The composition of volcanic rocks varies from basaltic composition, Basalitic andesites, andesite and , trachyandesite. On the basis of mineral chemistry the amphiboles are classified as calcic (magnesio-hornblende). Plagioclases vary from andesine-oligoclase to labradorite. Al-barometer accounts that the pressure of amphibole crystallization is 3.2 to 6.65 Kbar and Altotal versus Fetotal/(Mg+Fetotal) accounts the pressure between 4.5 to 7 Kbar. Hornblende - plagioclase thermometer shows 464 to 473 °C for equilibrium of these two minerals and biotite thermometer shows 500 to 650 °C for biotite in andesites. The estimated oxygen fugacity imply an oxidation magma (confirms iron oxide and enrichment of Mg in amphibole)
Seyed Hamid Vaziri; Mahmoud Reza Majidifard; Marc Laflamme
Abstract
The Precambrian Kushk Series in the Bafq and Behabad regions of Central Iran contains a diverse assemblage of latest Ediacaran fossils that showcase a fossil assemblage much more diverse than typically known from the latest Ediacaran systems worldwide. The Kushk Series reaches a thickness of >500 ...
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The Precambrian Kushk Series in the Bafq and Behabad regions of Central Iran contains a diverse assemblage of latest Ediacaran fossils that showcase a fossil assemblage much more diverse than typically known from the latest Ediacaran systems worldwide. The Kushk Series reaches a thickness of >500 m and consists of carbonate (sandy dolomitic limestone and dolomite) and siliciclastic (shale, sandstone, and siltstone) facies with extensive accumulations of volcanic rhyolite, microdiorite, and tuff, which its argillaceous shales contain an assemblage of abundant Ediacaran fossils including Kuckaraukia multituberculata,Persimedusites chahgazensis, Corumbella werneri, Cloudinasp., Chuaria sp., Kimberella persii, Gibbavasis kushkii, Erniettomorpha, Rangeomorpha and numerous tubular organisms. The discovery of classic terminal-Ediacaran index fossils Cloudina and Corumbella in this assemblage confirms a latest Ediacaran age (Nama-Assemblage ~545-539 Ma) for these deposits. These taxa help expand our understanding of the latest Ediacaran prior to the Ediacaran extinction and the Cambrian explosion of complex animals.
Tectonics
Saeid Hakimi Asiabar
Abstract
Abstract The area of Dona mine is a part of central Alborz. The Dona anticline is a part of pop up structure and located between Kandavan and Azadkuh thrust faults. In this research three sets of major faults are recognized. The first category of faults with W-E trend, dip 40-50, Rake angle more than ...
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Abstract The area of Dona mine is a part of central Alborz. The Dona anticline is a part of pop up structure and located between Kandavan and Azadkuh thrust faults. In this research three sets of major faults are recognized. The first category of faults with W-E trend, dip 40-50, Rake angle more than 70, are parallel to the major fold axes and second category of faults have NE-SW trend with reverse movement and rake angle less than 65. The third category which truncate the first sets, have nearly N30W to N40W direction with dip more than 75 and rake angle more than 70. The aim of this paper is investigation on the structure of Dona mine and investigations on the mechanism of third category of faults which are not popular in Alborz range and did not discussed before. Some of these faults do not have visible slickensides and the mechanism of these faults held on the basis of preparing geologic map on the scale of 1:1000, structural cross sections and implementing Schmidt net with construction methods. The change of tectonic movements from collision into sinstral, on the pop-up structure created this set of young reverse faults with NW-SE trend.
Economic Geology
Hadi Mohammaddoost; Majid Ghaderi; Jamshid Hassanzadeh
Abstract
Sulfur isotope data on pyrite, chalcopyrite and molybdenite in the A, B and D type veinlets in porphyry systems of the Meiduk cluster, located in northwestern part of the Kerman copper belt, show that these systems have near zero δ34S values. Sulfur isotope composition for the Chah-Firouzeh and ...
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Sulfur isotope data on pyrite, chalcopyrite and molybdenite in the A, B and D type veinlets in porphyry systems of the Meiduk cluster, located in northwestern part of the Kerman copper belt, show that these systems have near zero δ34S values. Sulfur isotope composition for the Chah-Firouzeh and Iju deposits and Serenu, God-e-Kolvari and Kader prospects is from -1.4 to +2.5 (average +0.31), -1.3 to +1.1 (average +0.07), +0.1 to +2.4 (average +0.87), -1.5 to +0.2 (average -0.1) and -4.1 to +1 (average -1.04), respectively. These results suggest a magmatic source for sulfur. Also, limited range of isotopic variations and analogous isotopic composition for the three types of veinlets reveals that with evolution of the hydrothermal system, no significant changes occurred in the primary and relatively homogenous source of sulfur. Comparison between the data for the Meiduk cluster with available data from other deposits in middle and southern parts of the Kerman belt suggested that in porphyry systems of the northwestern, and to some extent southern parts, of the Kerman Cenozoic magmatic arc, sulfur was provided by a mafic magma originated from metasomatized subcontinental lithospheric mantle (SCLM) which was affected by assimilation with continental crust; while in the southern parts, processes related to subduction and fluids from seawater and associated sediments had a major role in their sulfur isotope composition.
S. Alipour; Kh. Mosavi-ovenlegi; E. Hosseini; Sh. Aslanpour; Z. Haseli
Abstract
The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 ...
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The Urmia Salt Lake as the largest hyper saline lake of the world is located between west and east Azerbaijan provinces, NW Iran. Geochemistry of trace and rare earth elements of bed sediments taken from 25 Cm of the lower most of 1.5 meters depth of drilled holes in 130 samples between 2014-2015 were investigated. General geochemical composition of samples revealed a very heterogeneous variation of major oxides at NW, NE, SW and SE parts of the lake. MgO, CaO and Na2O show a high enrichment compared to UCC, PAA and NASC values. Main minerals of the bed sediments include halite, calcite, ankerite, quartz, orthoclase, augite, hornblende and chlorite. The overall geochemical composition of sediments, resemble ferruginous shale and graywacke sandstone. Weathering in the various parts of the bed sediments is relevant to general climatological characters in the region. Rb and Sr among trace elements show high anomaly in respect to UCC, PAAS and NASC, while Eu indicated high depletion, especially at SW corner of the lake. Geochemical comparisons indicate the major role of different rock units in forming bed sediments rather than sediments carried by entering rivers to the lake.
M. Morsali; M. Nakhaie; M. Rezaie; H. R. Naseri; J. Hassanpour
Abstract
Tehran- Karaj water conveyance tunnel (part 1), 16 kilometers in length, in the Karaj formation was excavated in order to convey the water from the Amir-Kabir dam to the Tehran refinery plant. The hydrogeology studies of the Karaj tunnel were done to discover the affecting parameters on the groundwater ...
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Tehran- Karaj water conveyance tunnel (part 1), 16 kilometers in length, in the Karaj formation was excavated in order to convey the water from the Amir-Kabir dam to the Tehran refinery plant. The hydrogeology studies of the Karaj tunnel were done to discover the affecting parameters on the groundwater inflow into the tunnel. Groundwater inflow was estimated by means of empirical and analytical methods. Daily measurements of inflow rate show that there are some differences between the calculated and the observed inflow value. In this research, based on the comparison between the observed and calculated groundwater inflow, some relations have been derived for similar hydrogeological conditions. In many hydrogeological conditions, the analytical equations are supervised on empirical formula. According to this research, addition to permeability and water head; geological structure, Precipitation and bedding dip have a significant effect in water inflow into tunnels. Also, most of groundwater inflow along the Karaj tunnel is largely related to the main geological features, such as folds, faults, dykes and open fractures and inflow is correlated with precipitation.
M Norouzi; M. Lotfi; M. H. Emami; H. Jamali; A. Abedini
Abstract
Mesgarabad area is located in ~10 km southeast of Tehran, the Central- Alborz structural zone (CASZ) of Iran. The rock units exposed in the area consist of Eocene volcanics, volcano-sedimentary and sedimentary rocks intruded by post upper Eocene granodiorite to quartz monzo-diorite. These subvolcanic ...
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Mesgarabad area is located in ~10 km southeast of Tehran, the Central- Alborz structural zone (CASZ) of Iran. The rock units exposed in the area consist of Eocene volcanics, volcano-sedimentary and sedimentary rocks intruded by post upper Eocene granodiorite to quartz monzo-diorite. These subvolcanic intrusive bodies show porphyroid to microgranular textures and have calc-alkaline magmatic nature. These bodies produced hydrothermal fluids causing extensive alteration zones developed along the Se-Darreh-e-Bozorg strike-slip fault. The effects of hydrothermal fluids on the entire Eocene rock units and subvolcanic intrusive bodies are remarkable. The main alterations are silicification, sericitization, chloritization, epidotizaton, actinolitization, argillization, carbonatization, and alunitization-jarositization, which provided suitable physico-chemical conditions for ore-mineralization. The penetration of subvolcanic intrusive bodies into the Eocene volcanics, volcano-sedimentary and sedimentary rocks brought about skarn mineralization and epithermal barite veins. Microscopic studies and advanced analysis showed that the principal mineral phases in the epithermal zones are magnetite, pyrite, chalcopyrite, bornite, chalcocite, barite, Cu+Sn+Fe alloy, hematite, psilomelane, jacobsite, martite, geothite, and lepidochrosite. The skarnification processes occurred at two distinct stages, (1) progressive and (2) retrogressive. The pyrometasomatic anhydrous minerals such as andradite-grossularite formed during progressive stage and the hydrous minerals like epidote, chlorite, tremolite- actinolite, calcite, quartz, pyrite, chalcopyrite and chalcocite were developed during retrogressive stage. Fluid inclusion studies on primary aqueous inclusions trapped in barite crystals revealed fluid that mixing of two fluids having different physico-chemical conditions played an important role for ore deposition.
A Abedini
Abstract
The Basir-Abad area (northeast of Ahar, East-Azarbaidjan province) is a part of the Cenozoic Ahar-Arasbaran magmatic belt in northwest of Iran. Intrusion of granitic and granodioritic igneous rocks of Oligocene age into the Eocene volcanic rocks (andesite, trachy-andesite, andesi-basalt and basalt) resulted ...
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The Basir-Abad area (northeast of Ahar, East-Azarbaidjan province) is a part of the Cenozoic Ahar-Arasbaran magmatic belt in northwest of Iran. Intrusion of granitic and granodioritic igneous rocks of Oligocene age into the Eocene volcanic rocks (andesite, trachy-andesite, andesi-basalt and basalt) resulted in occurrence of metallic mineralization along with development of widespread alteration zones in this area. Mineralogical studies indicate that these alteration zones include silicic (quartz), intermediate and advanced argillic (kaolinite, smectite, quartz and alunite), and propylitic (chlorite, epidote, albite and calcite). Hypogene ores within veins and veinlets of silicic alteration zone contain pyrite, chalcopyrite and galena accompanied by covellite, copper-carbonate minerals (malachite and azurite) and iron-oxides and- hydroxides (goethite, limonite and hematite) of supergene origin. The distribution patterns of REEs normalized to chondrite display differentiation and enrichment of LREEs relative to HREEs and occurrence of variant negative Eu anomalies in all alteration zones. Mass balance calculations of elements, using isocon method, indicate that during development and evolution of the silicic and the intermediate argillic alteration zones, REEs experienced enrichment in the former and depletion in the latter. Furthermore, development of advanced argillic and propylitic alteration zones was accompanied by enrichment of LREEs and selective depletion of HREEs. Further investigation revealed that occurrence of negative Eu anomaly (0.20-0.23) in silicic alteration zone is related to abundance of chloride ions, increase of oxygen fugacity of hydrothermal system and highly acidic nature of the fluid. The results obtained from geochemical studies (mass balance calculations, changes in values of Eu and Ce anomalies and ratios of REEs) suggest that changes of pH, temperature, oxygen fugacity, difference in abundance and type of complexing ions in solution, fluid/rock ratio, and presence of minerals such as kaolinite, goethite, smectite, hematite and alunite played important role in differentiation, mobilization and distribution of lanthanides in the studied alteration system.
S Abbasi; B Hamdi; M.R Majidifard
Abstract
Sampling and study of Devonian deposits in North West Iran has done in two separate sections. 1) Illangareh section, 20 km far from NE the Maku city 2) peyr-es-hag composite section, situated South Jufa (W of Peyr-es-hag and Chay kasan villages). Because less work has been undertaken in the cited sections, ...
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Sampling and study of Devonian deposits in North West Iran has done in two separate sections. 1) Illangareh section, 20 km far from NE the Maku city 2) peyr-es-hag composite section, situated South Jufa (W of Peyr-es-hag and Chay kasan villages). Because less work has been undertaken in the cited sections, in this research, microremains (fish teeth, scales and bone fragments) of Cartilaginous fish (Chondrichtyes), Osteichtyes (Acanthodians), fauna are known from the Devonian deposits. Index microvertebrates obtained from the cited above sections are: Siberiodus mirabilis, Phoebodus gothicus, Phoebodus turnerae, , Body scale Holonema sp., Sarcopterygian scale, Ischnacanthid jaw, Cheiracanthus sp., Ertychius intermedius Cladodus wildungensis. According to biostratigraphy and paleogeography these microremains can be comparing with other parts of Iran, neighbors, other parts of world. This assemblage show spread of shallow shelf environment of the northern margin of Gondwana during Middle-Late Devonian time.
S Hassanpour; S. Alirezaei
Abstract
The Masjeddgaghi Cu-Au deposit is located to the southeast of the Arasbaran zone, NW Iran, to the south of the Lesser Caucasus. Mineralization in Masjeddaghi is associated with an Eocene dioritic subvolcanic pluton intruded into older volcanic and sedimentary rocks. The Masjeddaghi intrusive body is ...
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The Masjeddgaghi Cu-Au deposit is located to the southeast of the Arasbaran zone, NW Iran, to the south of the Lesser Caucasus. Mineralization in Masjeddaghi is associated with an Eocene dioritic subvolcanic pluton intruded into older volcanic and sedimentary rocks. The Masjeddaghi intrusive body is high-K, calc alkaline, and meta-aluminous, and formed in an island arc subduction/collision setting. Hydrothermal alteration is distinguished by a potassic core marked by secondary biotite and K-spar that grades outward into a chlorite-rich propylitic halo. The ore minerals include chalcopyrite, associated with minor chalcocite, bornite, tetrahedrite, and trace molybdenite. Pyrite and magnetite are common associates. The Masjeddaghi deposit is elliptical in plan view, 500 x 400 m in diameters, and mineralization has been traced for several hundred meters from surface exposures. 40Ar/39Ar geochronology on secondary biotite from potassic alteration zone indicates that mineralization, and by corollary, the emplacement and crystallization of the Masjeddaghi porphyritic intrusion, occurred in 54.07 ± 0.53 Ma. The Masjeddaghi ore deposit shows geology, mineralization and alteration characteristics comparable to those typical of island arc type porphyry Cu-Au systems. Masjeddaghi ore deposit shows geology, mineralization and alteration characteristics similar to island arc porphyry type systems.
Economic Geology
A. Baharvandi; M. Lotfi; M. Ghaderi; M. R. Jafari; H. A. Tajeddin
Abstract
Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in ...
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Shekarbeig barite deposit is located 46 km southwest of Mahabad in northwestern part of the Sanandaj-Sirjan zone. The outcropped rock units in the area are Late Protrozoic metamorphosed volcano-sedimentary rocks, equivalent to Kahar Formation. The main ore mineral occurs as stratiform barite lenses in three horizons accompanied by sulfide minerals as massive and/or parallel bands within metamorphosed rhyolitic tuffs (metatuff). The deposit footwall is composed of phyllite and slate crosscut by silicic and sulfide-bearing barite veins and veinlets (stringer zone). Primary minerals in the ore are mainly barite, pyrite, marcasite, chalcopyrite and bornite and secondary minerals are chalcocite, covellite, malachite, siderite, goethite, hematite and other iron hydroxides. Gangue minerals include quartz, sericite, calcite, dolomite, feldspar and chlorite. In terms of metallic ores, the Shekarbeig deposit does not vary much having only pyrite and chalcopyrite. Types of fluid inclusions in the Shekarbeig deposit are two-phase liquid-vapour (LV), mono-phase vapour and mono-phase liquid; two-phase liquid-vapour being the dominant type in both stringer and stratiform parts. Sulfur isotope data indicate that seawater was the main mineralizing fluid for Shekarbeig mineralization. These data suggest that complete reduction of recent seawater sulfate and the rate of mixing of hydrothermal solution with cold waters in deep parts of the basin may result in precipitation of large amount of sulfides in the stringer and stratifrom zones. On the other hand, partial reduction of recent seawater sulfates provided required sulfur for the deposition of barite. Geological evidence, evaluation, lithostratigraphy, mineralization geometry and the results of fluid inclusion and sulfur isotope studies for samples from the Shekarbeig deposit indicate derivation of the hydrothermal fluids of low salinity and moderate temperature from seawater and circulation and upward movement by a heating source (probably subvolcanic intrusions) and finally cooling and deposition of the fluids as sulfate and sulfide on the sea floor due to mixing with seawater, similar to massive sulfide Kuroko-type deposits.
A. Abedini; A. Oroji; A. A. Calagari
Abstract
Thekaolinizedzonesof the Goorgoor area (north of Takab, West-Azarbaidjan province) are alteration products of andesitic rocks of Miocene age in northwest of Iran. Based on the mineralogical studies, kaolinite, quartz, jarosite, montmorillonite, albite, muscovite-illite, anatase, chlorite, orthoclase, ...
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Thekaolinizedzonesof the Goorgoor area (north of Takab, West-Azarbaidjan province) are alteration products of andesitic rocks of Miocene age in northwest of Iran. Based on the mineralogical studies, kaolinite, quartz, jarosite, montmorillonite, albite, muscovite-illite, anatase, chlorite, orthoclase, calcite, goethite and hematite are mineral phases in these zones. The silicic veins existing within these zones include metallic minerals such as pyrite, chalcopyrite, galena, sphalerite, bornonite, and stibnite. The mass change calculations of rare earth elements (REEs), with assumption of Sc as a monitor immobile element, reveal that development of kaolinization processes were accompanied by enrichment-depletion of La-Nd and depletion of Sm-Lu. Geochemical analyses show that the degree of differentiation of Al from Fe and destruction of zircon by hydrothermal fluids are the most important controlling factors for variation of Eu (0.84-1.06) and Ce (0.83-0.93) anomalies in these zones, respectively. Positive and strong correlations of (La/Lu)N and (LREEs/HREEs)N values with components such as P, S, LOI, and Sr establish the effective role of hypogene solutions in progression of kaolinization processes. The combination of the obtained results from mineralogical and geochemical investigations suggest that changes in chemistry of altering solutions (e.g., pH and Eh) and diversity in type of fixing minerals are two key factors affecting differentiation and distribution of REEs in the kaolinizedzones at Goorgoor.
A Amirpour Asl Miandoab; Q Sohrabi
Abstract
In this study, horizontal gradient and analytic signal methods have been applied to the reduced aeromagnetic data poled to Iran, to explore subsurface structures in the region. By using these two methods, it is possible to present a map of major geologic-magnetic structures especially large-scale faults ...
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In this study, horizontal gradient and analytic signal methods have been applied to the reduced aeromagnetic data poled to Iran, to explore subsurface structures in the region. By using these two methods, it is possible to present a map of major geologic-magnetic structures especially large-scale faults displaying magnetic signal in the region. Qualitative and quantitative results of this study were then prepared as maps and compared with previous studies. Finally, the agreements and disagreements observed against the previous studies were explained.
M Fadaeian; A Jahangiri; M Moayyed
Abstract
The study area is located in the Ardabil province and in the north east of Meshkinshahr city.More than 200 small and large Eocene age dykes have outcrops in this area with basaltic, tephritic, andesitic and trachy andesit composition. Clinopyroxene, plagioclase, analcime and sometimes coarse olivine ...
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The study area is located in the Ardabil province and in the north east of Meshkinshahr city.More than 200 small and large Eocene age dykes have outcrops in this area with basaltic, tephritic, andesitic and trachy andesit composition. Clinopyroxene, plagioclase, analcime and sometimes coarse olivine crystals are present in these rocks. Mineral chemistry studies suggested that clinopyroxene type in rocks is Diopside type. Existence of normal and reverse zoning in clinopyroxens deduces differentiation were effective factors on evolution of the rocks. Enriched elements Ti, Al, Na, and K of pyroxene core to the rim of the effect of metasomatism to in these rocks. Tectonomagmatic diagrams and compare the chemical composition of study area clinopyroxenes with other tectonic environment suggested that characteristics of alkaline rocks related to volcanic arc. According to geotermobarometric studies clinopyroxenes in study rocks formed at temperature 1150-1200ºC and pressure of 7-14 Kbars. The depth for generation of magma between 55-65 Km and average 60 Km estimated for these rocks.
S Soleymani; B Hamdi; A.R Karimi Bavandpur
Abstract
The studied section is located in the southern flank of the Central Alborz, 5 kilometers north of Shahmirzad City in the Semnan province. This section is situated at 35° 48′ 40″ N latitude and 53° 16′ 59″ E longitude. The Mila Formation has 5 measurable members in Type ...
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The studied section is located in the southern flank of the Central Alborz, 5 kilometers north of Shahmirzad City in the Semnan province. This section is situated at 35° 48′ 40″ N latitude and 53° 16′ 59″ E longitude. The Mila Formation has 5 measurable members in Type Section (Mila Kuh, Damghan City) and only in this studied section. This formation overlies conformably the Early Cambrian Lalun Sandstone Formation and underlies disconformably the Early Devonian red conglomerates. Studied Conodonts of this formation are of Proconodontus type belonging to Coniform Groups. 14 species and 6 genera of these conodonts were acquired indicating an age of Mid-Late Cambrian and Early Ordovician. These Conodonts are listed as below: Proconodontus serratus, Proconodontus muelleri, Proconodontus rotundatus, Prooneotodus sp?, Prooneotudus tenuis, Furnishina furnishi, Furnishina asymmetrica,Furnishina sp., Furnishina obliqus-Hirsutodontus?, Westergardodina cf. mossbergensis,Westergardodina fossa, Cordylodus, Cordylodus intermedius, Cordylodus lindstromi,Cordylodus proavus, Oneotodus nakamurai & Problematoconites sp. A remarkable point is the discovery of species Prooneotodus tenuis in the second member of Mila Formation because no conodont has already been reported from this member. Other microfossils such as Trilobites, Brachiopoda, Hyolithes, Eocrinoidae, Rusophycus, Cruziana, Paleoscoleidae and Sponges were also obtained indicating the deposition of Mila Formation in a shallow marine environment. These fossils assemblage are comparable with those from other parts of Iran and neighbor countries.
E Zarei; E Ghasemi-Nejad
Abstract
The Gurpi Formation at Farhadabad section in west of Darehshahr, was studied in detail for environmental changes and water–level fluctuations via using organic matter contents of the rock samples. Depositional environment interpretation was done based on integration of evidences derived from ...
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The Gurpi Formation at Farhadabad section in west of Darehshahr, was studied in detail for environmental changes and water–level fluctuations via using organic matter contents of the rock samples. Depositional environment interpretation was done based on integration of evidences derived from organic geochemistry analysis (TOC, TIC and Aliphatic n-alkane (short, mid and long chain n-alkane to sum of n-alkane, TAR (terrigenous-aquatic ratio), CPI(Carbon Preference Index), ratio of C17 to C27 and Isoperinoids (pr/ph,pr+ph/nC17+nC18, pr/nC17and ph/nC18) and palynofacies data (Amorphous organic matter, marine palynomorphs and palynomaceral). Statistical studies on palynomorphs confirm the results gained from the organic geochemical analysis. High ratio of palynomaceral and high TAR and CPI and dominance of long chain n- alkane and low ratio of C17/C27 (C17 relative to C27) and high ratio of Pr/Ph (>1) indicate regression condition at the base of the Gurpi Formation, Lopha Member, top of Emam-Hassan Member and Cretaceous – Tertiary boundary. On the other hand high abundance of marine palynomorphs and transparent amorphous organic matter and unimodal n-alkane with a marked even over odd predominance (CPI <1) and TAR <1 and high C17/C27 (C17 relative to C27) and low ratio of pr/nC17<0.5 indicate transgressive condition in upper part of Globotruncanita stuartiformis biozones, black shales between Lopha and Emam- Hassan, upper part of Contusotruncana contusa biozones and at the base of purple shale of the Pabdeh Formation. Maximum flooding surface probably equates the 70 Ma MFS K175, 68 Ma MFS K180 and 58 Ma MFS Pg10 of Sharland et al., 2001 that is recorded in many parts of the Arabian Plate. The relative sea level curve resulted in form this study is well in accord with the existing eustasy curves especially for the Campanian- Maastrichtian boundary indicating effect of eustasy on relative sea- level changes during this period. Combining all these data, an open marine environment with terrestrial organic input under suboxic to anoxic conditions can be concluded for the depositional course of the Gurpi Formation.
A.L Arab; M.R Vaziri
Abstract
A relatively thick sequence of Mid-Cretaceous (Aptian) strata exposed in Baghin area, west of Kerman, Iran. The strata comprise a diverse macro-fauna such as bivalves, echinoids, gastropods, corals and brachiopods. Among the bivalves, presence of a pectinid species, Neithea notabilis is relatively conspicuous. ...
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A relatively thick sequence of Mid-Cretaceous (Aptian) strata exposed in Baghin area, west of Kerman, Iran. The strata comprise a diverse macro-fauna such as bivalves, echinoids, gastropods, corals and brachiopods. Among the bivalves, presence of a pectinid species, Neithea notabilis is relatively conspicuous. The studies show a marked morphological variation in the species. Also, biometric analysis reveals a mark interspecific variation in the studied specimens. Low diversity in the genus Neithea could be due the high isolation of the Baghin area and therefore its limited connection to other water masses during the Mid-Cretaceous or because of its contribution to the diversification trend seen in the Mediterranean region.
B Taherkhani; H Nazari; M Pourkermani; M Arian
Abstract
The E-W trending North Qazvin Fault is situated in north & northeast of Qazvin city in south-central Alborz. Across the fault, Karaj formation (Eocene) is thrusted over Hezardarreh Formation (A) and the alluvial B Formation. It could be the source for the 1119 AD earthquake with an estimated magnitude ...
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The E-W trending North Qazvin Fault is situated in north & northeast of Qazvin city in south-central Alborz. Across the fault, Karaj formation (Eocene) is thrusted over Hezardarreh Formation (A) and the alluvial B Formation. It could be the source for the 1119 AD earthquake with an estimated magnitude of Ms: 6.5. The North Qazvin Fault is a seismically active fault, therefore it is one of the most important earthquake threats for the Qazvin as an industrial city of Iran. Morphotectonicand detailed field studies along a part of the North Qazvin Fault allows us to measure horizontal and vertical offsets caused by recent movements on this fault. One of the measured horizontal and vertical displacements due to the recent movements on the fault is 4 and 3.5 meters, respectively. The geometry (strike, dip and rake) of the North Qazvin Fault in this part is 090˚, 45˚, 51˚ respectively. Our investigations show that the North Qazvin Fault is a north-dipping compressional fault. The North Qazvin Fault and its surrounding faults such as Najm-abad fault appear as a propagating fault system which has left-lateral compressional kinematics in southern part of the west-central Alborz.
K Shiaian; J Ghalamghash; M Vosoughi Abediny; F Masoudi
Abstract
The Bazman volcano is located in the Makran Magmatic Arc. The pyroclastic rocks and lava with rhyodacitic to basaltic composition and calc-alkaline affinities erupted from the central and lateral craters of this volcano during the Quaternary period. The primitive mantle normalized Multi-elements diagrams ...
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The Bazman volcano is located in the Makran Magmatic Arc. The pyroclastic rocks and lava with rhyodacitic to basaltic composition and calc-alkaline affinities erupted from the central and lateral craters of this volcano during the Quaternary period. The primitive mantle normalized Multi-elements diagrams show a relatively high abundance of LIL relative to HFS incompatible elements with negative anomalies of Nb and Ti. Their chondrite–normalized REE patterns are slightly enriched in LREE relative to HREE with negative Eu anomalies. These geochemical features suggest that the volcanic rocks of bazman formed in a subduction setting by partial melting of metasomatized mantle. On the base of La/Yb vs Dy/Yb and La/Sm vs Sm/Yb diagrams the sources of the magmas is phlogopite-spinel-lherzolite or/and phlogopite-garnet- lherzolite.
Z Hamidi Beheshti; H Alimohammadian; M Talebian; A Shahidi; M.R Ghassemi
Abstract
Geomagnetism is one of the most applied techniques of geophysics in geology. Today, this method is applied in different disciplines such as Magnetic fabric of rocks, palaeomagnetism and environmental magnetism. Each of these magnetic methods is suitable for a particular lithology. Therefore, the potential ...
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Geomagnetism is one of the most applied techniques of geophysics in geology. Today, this method is applied in different disciplines such as Magnetic fabric of rocks, palaeomagnetism and environmental magnetism. Each of these magnetic methods is suitable for a particular lithology. Therefore, the potential of sandstones of Shemshak Group, in central AlborzMountain range were examined to record their response to the application of some conventional magnetic methods. This rock unit is formed during two major tectonic events of early and middle Cimmerian and has great coverage not only in the study area but also in a vast majority of Iran. The total number of 135 oriented core samples was taken from 18 stations. In this study combination of magnetic and petrographic data are examined. The result of magnetic mineralogy analysis of all samples (except samples from stations 10 and 15) show irreversibility i.e. minerals such as hematite and magnetite, have formed during the heating stage. The results of thermal demagnetization analysis showed that ferromagnetic minerals present in the samples (except samples from stations 10, 14 and 15) have demagnetized below 400 °C and by proceeding heating, samples show zigzag pattern or show abnormal increase in susceptibility. This indicates that, the magnetic minerals are formed during heating in one stage and due to unstability lose its susceptibility in other stage. The magnetic susceptibility (Km) vary from 200-400×10-6 SI for more stations of study area, indicating abundance of paramagnetic mineral in this rock unit. From petrography point of view all the sandstone samples are classified as arenites and ratio of quartz to lithic fragment and feldspar is relatively low, which may indicate low mineral maturity. Comparison of magnetic mineralogy and thermal demagnetization data for two stations S10 and S15 show that there is an inverse potential relationship between amount of stable ferromagnetic mineral in a sample and amount of its alteration during heating stage. The results of this study reveal the poor nature of Shemshak Group sandstones for palaeomagnetic studies due to their low mineral maturity and water percolation which increase the possibility of acquisition of chemical remanent magnetization (CRM). The high sedimentation rate of sandstones cause magnetic inclination and declination error, and low ferromagnetic mineral fraction in samples, make them unsuitable to record magnetic directionsduring formation of rocks. However, abundance of paramagnetic minerals such as biotite in these rocks, proves their applicability for magnetic fabric studies.
M Shademan; A.R Arab-Amiri; H Kheyrollahi; D Rajabi
Abstract
Frequency Domain Electromagnetic surveys are being used for various applications like mineral and water exploration, environmental hazards and buried human-made materials because of its resolution and fast acquisition for low depth targets. Resistivity and its depth for each frequency could be calculated ...
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Frequency Domain Electromagnetic surveys are being used for various applications like mineral and water exploration, environmental hazards and buried human-made materials because of its resolution and fast acquisition for low depth targets. Resistivity and its depth for each frequency could be calculated in a simpler approach and shorter time than Iterative Inversion Method, Called Straight or Fast Inversion Methods, by assuming earth as a homogeneous half space. Barika’s Anomaly situated in Alut Geology 1:100,000 sheets in west Azerbaijan is studied in order to prospect gold_ lead mineralization which has been detected in systematic geochemical and litho-geochemical surveys. In this paper we studied different Fast Inversion algorithms for synthetic data then applied the best method for real data. Resistivity distribution for each frequency produced and appropriate interpretation according to geology acquired. The results showed that there is a good correlation between low resistivity and shear zones. Also geology map can be modified with higher frequency resistivity.
S Ghaderi; E Rastad; N Rashidnezhad-Omran
Abstract
Tungsten (Cu-Au) mineralization of Southern Chah Palang (SCP) deposit, located in middle part of the Yazd block, occurred as vein-veinlet in normal fault zones, which cut the sandstones and shales of Early-Middle Jurassic Shemshak formation. Based on the mineral paragenesis and quartz type, color and ...
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Tungsten (Cu-Au) mineralization of Southern Chah Palang (SCP) deposit, located in middle part of the Yazd block, occurred as vein-veinlet in normal fault zones, which cut the sandstones and shales of Early-Middle Jurassic Shemshak formation. Based on the mineral paragenesis and quartz type, color and texture, ore-bearing veins can be divided into 1) k-feldspar, apatite (I) bearing milky-white quartz veins, 2) white quartz veins contain apatite (II), 3) hematite- white quartz veins and 4) late carbonate veins. Wolframite is the main tungsten ore mineral in the SCP deposit, which occurred in type 1 vein. Wolframite crystals are riched in Fe and have ferberite composition. Scheelite, as next tungsten ore mineral in SCP deposit, formed in 2nd generation and show significant enrichment in As. Scheelite (I) coexist with Wolframite in type 1 veins, and Scheelite (II) replace wolframite in its fractures and rims, also with arsenic-bearing phases occurred in type 2 veins. Gold in SCP deposit occurred as coexist with and/or fine inclusions in Scheelite (II). Other ore minerals that formed in type 2 veins include base metals and Fe sulfides, cobaltite, niccolite, Cu-Ni-Fe sulfides and native bismuth. Type 3 and 4 veins are white quartz-hematite and barren carbonate veins.
δ18 O of ore-forming fluids, which milky-white and white quartz and wolframite formed from them are 7.91-8.61‰, 5.86-6.76‰ and 3.44-6.94‰ respectively. Based on the oxygen isotope studies, progressive mixing of original magmatic fluids with meteoric waters cause precipitation of metals in veins.
j Darvishi Khatouni; R Lak; A Mohammadi
Abstract
The Lake Urmia is the greatest hyper saline Lake in the world. This lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meters. Hydrochemistry of the water resources of the basin showed mainly chloridic ...
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The Lake Urmia is the greatest hyper saline Lake in the world. This lake, located in Azerbaijan area, Northwest of Iran is an intra-continental sedimentary basin. Its area is about 6000 km2 with an average water depth of 6 meters. Hydrochemistry of the water resources of the basin showed mainly chloridic and sulfidic composition due to the geology of the surrounding areas and its variable lithology and Inlet water are supplied from the permanent and seasonal rivers. The hydrochemical investigations were carried out over a time period from 2007 to 2012 using previously published data together with newly collected water samples. 120 samples were collected during 6 years. The analaysis results showed Na-Mg-Cl type of the brinefrom 2007 to 2010, which is comparable with the Great Salt Lake in the USA. The chemical composition of lake in 2007 showed the percentage of sodium is higher than Magnesium. In 2011 and 2012 water composition is HCO3<<Ca+Mg. That is, the path of brine composition on the Eugster and Hardie flow diagram has changed from row III2b (Na-Mg-Cl) to (Mg-Na-Cl) in 2011 and 2012 after halite crystallization and may finally result in Mg-Cl-SO4 brine type in the future. The Sodium to Magnesium ratio is 5.12 in 2007. However, this amount in 2011 is 0.68 and 0.56 in 2012. In future, with Increasing ofevaporation, the Magnesium to sodium ratio increases and chemical compositions of the brine in the north and south of the Shahid Kalantari Highway experience more difference.
H Karimian zade; M.R Vaziri; A Lotf abad Arab
Abstract
In order to study the paleoecology of the Aptian gastropods, the Bafgh section with 380 meters thickness, in East of Yazd were studied in detail. In this region, a variety of different fossil groups, including macrofossils (gastropods, ammonites and echinoids) and microfossils (foraminifers and ostracods) ...
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In order to study the paleoecology of the Aptian gastropods, the Bafgh section with 380 meters thickness, in East of Yazd were studied in detail. In this region, a variety of different fossil groups, including macrofossils (gastropods, ammonites and echinoids) and microfossils (foraminifers and ostracods) are present and suggest an Aptian age for this section. 11 genus and species of gastropods are reported for the first time from this section. The microfossils and macrofossils assemblage all show a shallow environment with a suitable conditions for the time of sedimentation in the study area.
M Aghazadeh; Z Badrzadeh
Abstract
In the northwestern Iran mica-and amphibole-rich lamprophyres crop out mainly as dyke and they cut Pre-Pliocene strata. They exposed in the Arasbaran, EslamyPeninsula, and Mishu range. According to the mineralogy and mineral chemistry, amphibole-rich lamprophyres have kaersutite type amphiboles and diopside ...
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In the northwestern Iran mica-and amphibole-rich lamprophyres crop out mainly as dyke and they cut Pre-Pliocene strata. They exposed in the Arasbaran, EslamyPeninsula, and Mishu range. According to the mineralogy and mineral chemistry, amphibole-rich lamprophyres have kaersutite type amphiboles and diopside phenocrysts in the matrix of same mafic minerals, feldspars, and altered glass. These lamprophyres in some thin sections have olivine and phlogopite. Mica-rich lamprophyres include phlogopite and diopside phenocrysts in the matrix of same mafic minerals, abundant glass and secondary minerals. According to the mineralogy, mineral chemistry, and geochemistry, amphibole-rich lamprophyres are alkaline and show camptonite-sannaite composition but mica-rich lamrophyres are calc-alkaline and represent minette composition. Alkaline lamprophyres represent characteristics of OIB type magma while calc-alkaline lamprophyres show characteristics of magmas originated in the subduction dominant tectonic setting. Sorkheh amphibole-bearing lamprophyres show both alkaline and calc-alkaline type lamprophyres. Regarding to geochemical features both calc-alkaline and alkaline lamprophyres originated from heterogeneous mantle with different proportions of spinel, garnet and hydrous minerals (e.g. phlogopite and amphibole). Calc-alkaline lamprophyres originated from a mantle enriched in phlogopite and alkaline lamprophyres originated from lithospheric mantle that metasomatised by deep mantle and enriched in amphibole. Both mentioned mantles associated in the petrogenesis of the Sorkheh amphibole- bearing lamprophyres. The lamprophyres were emplaced in the post collisional tectonic setting.