Stratigraphy and Palaeontology
Ali Jalali; Hamed Yarahmadzahi; Mehran Arian; Abdollah Saidi; Seyed Mohsen Aleali
Abstract
The Shishtou section is located in the north of Tabas Ghezelin and Asselian sequences of Zaladou formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the ...
Read More
The Shishtou section is located in the north of Tabas Ghezelin and Asselian sequences of Zaladou formation with 60 m thickness are divided into five units, includes sandstone, limestone, shale, sandy limestone and limestone. The lower boundary of the Gzhelian deposits with disconformity on top of the Moscovian deposits of the Abshani formation. The upper boundary of these deposits with the Tighe-Madanou formation is continuous. The assemblages of fusulinids in the Shishtou section such as Ruzhenzevites-Rauserites-Triticites are identified in the upper part of Gzhalian previously reported from equal deposits in Darvaz, Fergana, Southern Urals, Donetsk and Carnic of Alps, as well as, Central Iran, Central Alborz and Sanandaj-Sirjan zones. Also, different species of Sphaeroschwagerina, Pseudoschwagerina and Likharevites, which illustrate the Asselian age, represent the Carboniferous-Permian boundary in the studied section and allow for comparability with other structural-sedimentary zones of Iran, including Central Iran , Central Alborz (Doroud Group) and Sanandaj-Sirjan zone. This equivalence expresses the transgressive of sea level in different parts of Iran in the late Carboniferous and early Permian periods. In Shishto section 15 genera ,35 species and 2 subspecies of Fusulins have been identified, some of which are reported for the first time from Iran.
Geophysics
Marzie Shabani; Abolfazl Rezaei; Zohre Masoumi
Abstract
The water table in the Zanjanrood catchment has severely declined recently. Therefore, determination of the groundwater potential zoning map is of great importance for optimal management of water resources. Here, we used seven effective criteria including lithology, slope, drainage, lineament, rainfall, ...
Read More
The water table in the Zanjanrood catchment has severely declined recently. Therefore, determination of the groundwater potential zoning map is of great importance for optimal management of water resources. Here, we used seven effective criteria including lithology, slope, drainage, lineament, rainfall, spring density and landuse to asses groundwater potential. The analytical hierarchical analysis process was used for weighting the criteria. Overlay analysis was implemented using TOPSIS model to prepare the groundwater potential map in four categories of priority including very-good, good, low and poor. In general, the very-good category corresponds with the first priority while the lowest potential of groundwater match with the fourth priority. The high-discharged production wells and the geoelectrical investigations (resistivity and induced polarization) were applied to verify the model. The spatial distribution of the high-discharge production wells has completely coincided with both the very-good and good priorities in the area. The results of resistivity and IP models also are in good agreement with those from the TOPSIS model. Overall, the results suggest there is no rich aquifer in mountains of the Zanjanrood catchment. Furthermore, the most important aquifer in the Zanjanrood catchment is located around the Zanjanrood River where a severe water table decline has occurred.
Stratigraphy and Palaeontology
maryam naderiyan; elahe zarei; khadijeh Mohammad-khani
Abstract
The Dalichai Formation in Darjazin section in NE Semnan with a thickness of 631 meters consisting of an alternation of bulish-gray was studied. This formation overlies the Shemshak formation disconformity with conglomerate bed and it has gradually been covered by the thick-beded limestones of the Lar ...
Read More
The Dalichai Formation in Darjazin section in NE Semnan with a thickness of 631 meters consisting of an alternation of bulish-gray was studied. This formation overlies the Shemshak formation disconformity with conglomerate bed and it has gradually been covered by the thick-beded limestones of the Lar formation. In order to study paleoenviroment of the Dalichai Formation the authors examined many different factors including Microfacies and palynological data (abundance and diversity of Dinocyst, proximate to chorat Dinocyst, palynofacies analysis and "selective preservation of organic matter"). A high percentage of brown wood and sporomorphs and the dominance of cavate and proximate dinocysts such as Nannoceratopsis gracilis, and pareodinia ceratophora and fluorescent amorphous organic matter, as well as Miliolid benthic foraminifera are evidence of suboxic to anoxic condition, which favored accumulation and preservation of organic matter in open marine lagoon, in the lower part of Dalichai Formation. A decrease in the brown wood and abundance and species richness of marine palynomorph (mainly chorate dinocysts) reflects more offshore settings in the upper part of Dalichai Formation. On the other hand, Appearance and increase of planktonic foraminifera and Radiolar and posidonia indicate development of strong marine transgression and deposition in an open marine environment.
Stratigraphy and Palaeontology
Mir Amir Salahi; Abbas Ghaderi; Alireza Ashouri; Ali asghar siabghodsi
Abstract
To separate the different units of the Paleogene sequences of the Kopet-Dagh basin and their regional correlation with the adjacent areas in the Central Asia, the Oyster bivalves fossils are used in the current research. Also, the study of their paleobiogeography has been considered in this study. Based ...
Read More
To separate the different units of the Paleogene sequences of the Kopet-Dagh basin and their regional correlation with the adjacent areas in the Central Asia, the Oyster bivalves fossils are used in the current research. Also, the study of their paleobiogeography has been considered in this study. Based on this fauna, Pycnodonte-Oestra community in the Chehelkaman Formation uppermost parts represents the late Paleocene age and the first occurrence of Flemingostrea hemiglobosa at the base of the Khangiran Formation confirms the beginning of Eocene epoch. Association of different species and subspecies of Turkostrea in the Khangiran Formation demonstrates the middle part of early Eocene and Sokolowia community near the top of the Khangiran Formation shows the Lotetian-Bartonin ages. These features are in full compliance with the bivalve communities recorded from the other parts of Central Asia such as Amu-Darya, Farghana, Afghan - Tajik and Trim basin of China. It illustrates the same geological history of the mentioned areas during Paleogene, indicates the occurrence of different types of molluscan taxa in the Kopet-Dagh basin is the same as parallel horizons and equivalent time units throughout the extensive Central Asian region.
Petrology
manijeh Asadpour; Soraya Heuss
Abstract
Acidic patches with alkali-granite nature have been intruded within the mafic rocks of the Qushchi complex (70 Km north of Urmia city). This area is northwestern part of the SSz zone with Precambrian basement. These granits have high amounts of K2O and SiO2 (over 70 wt%). Dating by U-Pb age of zircon ...
Read More
Acidic patches with alkali-granite nature have been intruded within the mafic rocks of the Qushchi complex (70 Km north of Urmia city). This area is northwestern part of the SSz zone with Precambrian basement. These granits have high amounts of K2O and SiO2 (over 70 wt%). Dating by U-Pb age of zircon grains show 303.4 ± 2.2 Ma, indicating late Carboniferous - early Permian magma activity. The presence of older cores in some of zircon grains with age between 400 to 600 Ma, indicate presence of older rocks in the study area. The whole-rock isotopic analysis show negative initial Nd (t) = -1.3 with TDM = 1.61. These data provide evidence for partial melting of crust (with Neoproterozoic- Cambrian age) in early Permian. The 87Sr/86Sr = 0.752348 and εNd = -1.4 of whole rock and Th/U (>0.5) values in zircons show the involvement of more crustal and less mantle components, during the opening of Neo-Tethys Ocean. Due to the same mineralogical and geochemical composition and homogeneity with Qushchi granite, it is inferred that these patches are genetically related to Qushchi granite and are A type granite.
Tectonics
Mohamad Reza Sajadian; Manouchehr Ghorashi; Elahe Javadi Mosavi; Mohsen Pourkermani; Mehran Arian
Volume 28, Issue 110 , December 2018, , Pages 299-306
Abstract
Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics. These indices have the advantage of being calculate from ArcGIS and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics. ...
Read More
Geomorphic indices of active tectonics are useful tools to analyze the influence of active tectonics. These indices have the advantage of being calculate from ArcGIS and remote sensing packages over large area as a reconnaissance tool to identify geomorphic anomalies possibly related to active tectonics. This is particularly valuable in west-central Alborz where relatively little work on active tectonics based on this method was done, so this method is new and useful. Based upon values of the stream length-gradient index (SL), drainage basin asymmetry (Af), hypsometric integral (Hi), ratio of valley-floor width to valley height (Vf), index of drainage basin shape (Bs), index of mountain front sinuosity (Smf) and transverse topographic symmetry factor (T), we used an overall index (Iat) that is a combination of the other indices. The low class of Iat are mainly in the sub-basins no; 6, 10,13,14,21,22,23,24,28 and the rest of the study area has moderate tectonic activities in the other sub-basins. Our results show that he moderate value has located along faulted area, which shows 2 class of relative tectonic activity.
Stratigraphy and Palaeontology
Abdolvahab Kazemi; Nasrollah Abbassi
Abstract
Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan province, southwest Iran. Numerous vertebrate footprints have been found in the middle part of the Formation, which includes footprints ...
Read More
Agha Jari Formation (Miocene-Pliocene, 788 m) comprises alternations of sandstone, siltstone, and marl in red to brown color layers in the east Gotvand, north Khuzestan province, southwest Iran. Numerous vertebrate footprints have been found in the middle part of the Formation, which includes footprints of wetland small bird (Aviadactyla media, Gruipeda dominguensis), artiodactyls (Lamaichnum alfi, Lamaichnum isp., Pecoripeda satyri, Pecoripeda isp.), canids (Canipeda isp.) and large reptiles (Hatcherichnus sanjuanensis). Frequency of artiodactyl imprints are more than the other footprints. These footprints proof the living of camels and crocodiles in the Zagros basin for the first time. The ichnotaxa diversity of the footprints in the studied section is more than the other reports of Agha Jari Formation in Iran and its stratigraphic equivalent in the adjacent countries.
Exploration and Mining
Amir Salimi; Samaneh Barak; Mahyar Yousefi
Abstract
An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical ...
Read More
An accurate threshold value makes a precise geochemical separation into anomaly and background areas. The threshold assignment using structural methods are preferred to non-structural methods. In this research, the U-spatial statistics, a structural based method, was used to study soil type geochemical data of the Neysian region. The optimal U-values obtained by this method for each sample were successfully utilized to separate the abnormal and background samples, accurately. In addition, based on the optimal distance of each sample, the abnormal samples identified in the previous step were classified in terms of geochemical intensity into strong, medium and weak samples. The goodness of U-spatial statistics performance in identifying abnormal areas were validated using drilled boreholes in the area. The U-spatial statistics not only succeeded in correctly identifying anomalous samples, but it also correctly identified some samples as the background whiles they had been recognized as anomaly by a non-structural method. All results obtained were validated by the several drilled boreholes.
Petrology
Shima Shomali; Mansour Ghorbani; Mohamad Reza Ghasemi
Abstract
The Marphioon pluton in the central part of Urmia-Dokhtar magmatic arc is among the Neotethyan oceanic lithosphere subduction-related intrusions. The composition of this pluton changes from granodiorite to tonalite. Marphioon granitoid gives rise to contact aureole zone with different peripheral thicknesses. ...
Read More
The Marphioon pluton in the central part of Urmia-Dokhtar magmatic arc is among the Neotethyan oceanic lithosphere subduction-related intrusions. The composition of this pluton changes from granodiorite to tonalite. Marphioon granitoid gives rise to contact aureole zone with different peripheral thicknesses. U-Pb geochronology of a sample from southern outcrop suggests that these rocks have crystallized at 18.89±0.20 Ma in Early Miocene.These rocks belong to medium-K calc-alkaline series with I-type affinities. In terms of geodynamic setting, this intrusion is classified as volcanic arc granites and active continental margin granites. Qualitative interpretation of aeromagnetic data suggested a diorite to gabbroic composition due to high magnetic susceptibility.The Marphioon intrusion is strongly tectonized due to faulting. Basement dextral strike-slip faults and their sinistral conjugates are potential mechanisms for its exposure. It seems that the Marphioon magma in an active continental margin, originated from the partial melting of the lower continental crust with the involvement of mantle-derived melts, where mafic magma in mantle wedge has provided optimal temperature and fluids for this melting in the lower crust. Collectively, Marphioon intrusion seems to be emplaced during the transition time from subduction to collision in the Urmia-Dokhtar magmatic arc contemporaneous with the closure of the Neotethyan ocean.
Economic Geology
Mehdi Moradi; Ebrahim Tale Fazel
Abstract
Mouchesh gold deposit (0.7 Mt @ 1.3 g/t gold) is located in the Takab-Delijan gold belt. Mineralization with several 28 gold-bearing quartz-sulfide veins (N40E-trending, 1 to 10 m wide, and 5 to 200 m long) has been formed in the host of Lower Cretaceous andesite and andesitic lithic tuff units. Open ...
Read More
Mouchesh gold deposit (0.7 Mt @ 1.3 g/t gold) is located in the Takab-Delijan gold belt. Mineralization with several 28 gold-bearing quartz-sulfide veins (N40E-trending, 1 to 10 m wide, and 5 to 200 m long) has been formed in the host of Lower Cretaceous andesite and andesitic lithic tuff units. Open space-filling, comb, and disseminated textures are important mineralization textures that were formed in quartz-sulfide±gold veins (vein I) and quartz-barite-galena (vein II), which and cut later by carbonate veins (vein III). The homogenization temperature (Th) and salinity of the fluid inclusions, respectively, with an average temperature of 180 °C and salinity of 0.2 wt% NaCl eq. (vein I), 155 °C and 1.6 wt% NaCl eq. (vein II), and 135 °C and 1.5 wt% NaCl eq. (vein III). The values of δ34S in sulfide minerals of veins I and II are between +0.1 to ‒3‰ (δ34SH2S between ‒0.3 to +0.4‰), which indicates a single magmatic source for sulfur. The results of this research reveal that the existence of hydrostatic conditions (e.g., boiling) in the Mouchesh deposit has caused H2S releasing from the hydrothermal fluid, the decrease in the solubility of the bisulfide complex Au(HS)‒2, and ultimately the gold instability.
Economic Geology
Pooya Seyed Salehi Naeini; Saeid alirezaei
Abstract
The Kharestan-Bidester area, northwest of the Taftan volcano, is covered by a series of Plio-Quaternary lava flows and pyroclastic materials. The area is marked by extensive silicic and argillic alterations. The silicic zones, distinguished by vuggy texture, are bordered by advanced-intermediate argillic ...
Read More
The Kharestan-Bidester area, northwest of the Taftan volcano, is covered by a series of Plio-Quaternary lava flows and pyroclastic materials. The area is marked by extensive silicic and argillic alterations. The silicic zones, distinguished by vuggy texture, are bordered by advanced-intermediate argillic alterations. They occur as linear features across faults and fractures, as well as massive bodies of variable sizes, and are comparable, at regional scale, to lithocaps developed in the upper parts of the porphyry systems. The silicic-argillic zones are mineralized with gold at variable grades. Gold occurs mostly as submicroscopic particles of electrum and native gold. Pyrite, variably oxidized at surface and shallow levels, is the main metallic mineral, associated with trace sulfosalts, tetrahedrite and enargite. Minor malachite staining locally occurs in the ore zones. The geologic setting, hydrothermal alteration, ore mineralogy and texture/structure allow the Kharestan-Bidester to be compared with high-sulfidation epithermal systems.
Petrology
Seyevahid Shahrokhi
Abstract
The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic ...
Read More
The Dalayon granitoid is located in the south of Borujerd and, is part of the Sanandaj-Sirjan zone. The lithological composition includes granodiorite, granite, pegmatite-granite, tonalite, quartz diorite, tourmaline-bearing pegmatite, and quartz-tourmaline veins intruded into volcanic and metamorphic rocks. The minerals set of granodiorite mass with color leucocratic to mesocratic index mainly minerals quartz, plagioclase, orthose and microcline and secondary minerals biotite, muscovite, zircon, garnet, apatite, rutile, leucoxene, and sphene. The indicator mineral of ferromagnesian in these rocks is biotite, which has a primary nature rich in magnesium and poor in chlorine in composition. The value of Fe/Fe+Mg ratio shows an average 0.44(apfu), that indicates that the studied micas are placed in the range of biotite and between siderophiles and anite poles. The average crystallization temperature of biotites is 681ºC and the average formation pressure is 2.95kb based on the total aluminum of biotites, which indicates formation at a shallow depth. Based on the proportions of MgO- FeO-Al2O3 in biotites, the magma that produced this mineral is of the calc-alkaline type. The existence of relatively high fugacity of oxygen and oxidant environment indicates magma of mantle-crust origin and host rock of magnetite granitoid series and I-type granitic rock for biotites.
Geological Environment and Engineering
razieh Lak; Ali Mohammadi; Javad Darvishikhatooni; Elnaz Aghaali
Abstract
Heavy rain falls in dray seasons with extreme water flow is one of the important factors in very intense damage urban areas and agricultural lands of the of arid and semi-arid plateaus and highlands. In semi-arid area such as southern flank of Alborz Mountain, neglecting the effect of geomorphologic ...
Read More
Heavy rain falls in dray seasons with extreme water flow is one of the important factors in very intense damage urban areas and agricultural lands of the of arid and semi-arid plateaus and highlands. In semi-arid area such as southern flank of Alborz Mountain, neglecting the effect of geomorphologic features, (e.g. river truck channel depth, slope, sinuosity, river flood plain width and slope), illegal construction on the river legal boundary, as well as the effect of present-day climate change (change in annual rainfall precipitation and patterns, especially in El Niño conditions), cause environmental hazards such as extreme floods in urban areas. Imamzadeh Davood village is a religious-tourist place in the central the Alborz In this research, we investigated the 28th July, 2022 Imamzadeh Davood flood controlling factors and its effect on low-stream village (Imamzadeh Davood) and provided scientific solutions to decrees and prevent the destructive effect of future potential floods. The unusual extreme flood occurred after heavy and sudden rain in July (usually the area receives almost 0 cm of precipitation), causing a large volume of high-density mud flow with highly destructive power in the upper catchment.
Stratigraphy and Palaeontology
JAVAD SAADATNEJAD
Abstract
Kalariz formation beds in Javaherdeh area has well exposure for plant macrofossils study. The studied area is located at the northern Alborz structural-facies zone, The Kalariz formation in Javaherdeh section consists of shale, siltstone, sandstone and conglomerate beds with coal veins and intrusive ...
Read More
Kalariz formation beds in Javaherdeh area has well exposure for plant macrofossils study. The studied area is located at the northern Alborz structural-facies zone, The Kalariz formation in Javaherdeh section consists of shale, siltstone, sandstone and conglomerate beds with coal veins and intrusive beds. It lies conformably, with a coarse grain sandstone bed, on top of the Laleband formation . Its upper contact is unconformable and sharp under the conglomerate beds of Javaherdeh formation. In this study 29 species of plant macrofossils from 13 genera were studied and introduced, including orders of Equisetales, Osmundales, Filicales, Cycadales, Bennettitales, Ginkgoales and Coniferales and an unknown reproductive organ. On the basis of the occurrence of index fossils such as Cladophlebis nebbensis, Nilssonia brevis, Dictyozamites asseretoi, Taeniopteris reversa, Taeniopteris tenuinervis and Baiera muensteriana Rhaetian age, and based on the occurrence of index taxa such as Dictyophyllum exile, Pterophyllum aequale and Pterophyllum bavieri, Late Rhaetian age is proposed for this assemblage. In this study, Ginkgoites whitbiensis from Iran and Taeniopteris reversa from Alborz are recorded for the first time. Clathropteris elegans, Nilssonia harrisi, Ginkgoites parasingularis and Ginkgoites lepida are recorded for the first time from Late Triassic beds of Iran
Tectonics
Babak Samani
Abstract
The use of spatial orientation of structural elements provides a great help to understand the geometry of shear zones. Investigating the indices of non-axial deformable flow in two areas of shape preferred orientation (SPO) and lattice preferred orientation (LPO) of quartz in the deformed rocks of Koli ...
Read More
The use of spatial orientation of structural elements provides a great help to understand the geometry of shear zones. Investigating the indices of non-axial deformable flow in two areas of shape preferred orientation (SPO) and lattice preferred orientation (LPO) of quartz in the deformed rocks of Koli Kosh complex in the Sanandaj-Sirjan metamorphic belt at the north of Fars province show the dextral shear component. Quartz c-axis preferred orientation indicates the dominance of bulging and sub-grain rotation recrystallization in the thermal range of 379±50 to 448±50 degrees Celsius and pressure of 3 to 3.5 kbar. According to stereography projection of pole of foliation and lineation the plane of vorticity normal section was estimated as N15W/45SW. Assuming the compatibility of the north and south thrust systems with the boundary of the shear zones, the rake angle of the boundary of the shear zone and the vorticity normal section was calculated equal to 19 degrees. Therefore, it is possible to consider the oblique transpiration model with triclinic geometry as the structural evolution model of this shear zone.
Petroleum geology
Fatemeh Taghizadeh; Khaled Maroufi; Reza Falahat; Ali Opera
Abstract
Objective of this study is to conduct a geochemical assessment over source candidates in the Garangan oilfield using Rock-Eval pyrolysis and vitrinite reflectance to identify factors contributing to the lack of hydrocarbon reserves in the Middle Cretaceous – Early Oligocene petroleum system. Furthermore, ...
Read More
Objective of this study is to conduct a geochemical assessment over source candidates in the Garangan oilfield using Rock-Eval pyrolysis and vitrinite reflectance to identify factors contributing to the lack of hydrocarbon reserves in the Middle Cretaceous – Early Oligocene petroleum system. Furthermore, the impact of mineral matrix retention, inert organic material (OM) and maturity were examined, and the results were used to split TOC and S2 parameters into the oil-prone and gas-prone components. Based on results, Pabdeh formation is an immature rich source, exhibiting the highest levels of active OM. Unexpectedly, OM quantity for the Kazhdumi source rocks is fair, for which contribution from inert OM is substantial. Significant inert OM is also confirmed for the oil/gas-prone upper Dariyan shales and gas-prone Gadvan samples. These characteristics seem to be related to the activities of the Khark-Mish paleo-high during the Cretaceous. Moreover, the Cretaceous intervals show a maturity level equivalent to the preliminary stages of main oil generation phase. Finally, owing to the presence of high-quality reservoir and cap strata, the absence of economical reserves in the Asmari and Bangestan reservoirs of the oilfield is possibly related to mediocre OM quantity and quality, and insufficient maturity of the source candidates.
