Economic Geology
Hossein Bagherpour; Mir Ali Asghar Mokhtari; Hossein Kouhestani; Ghasem Nabatian
Abstract
Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, ...
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Qoyjeh Yeylaq volcanic rocks is located approximately in the 120 km southwest of Zanjan, within the Central Iranian zone. The rock units in this area belong to the Cenozoic which consist of mainly Oligo-Miocene volcanic (Basaltic- andesitic lavas) and sedimentary rocks. Based on geochemical classification, the mentioned volcanic rocks are basalt, basaltic andesite and andesite in composition, and have calc- alkaline to high-K calc-alkaline affinity. In the primitive mantle normalized spider diagrams, all of the volcanic rocks show similar patterns with enrichment in LILE (Ba, Th, K, Pb) and negative anomalies of HFSE (Nb, Ti). These rocks show LREE enrichment relative to HREE and high ratio of LREE/HREE. Based on tectonomagmatic discrimination diagrams these volcanic rocks were formed in a continental arc setting. Based on geochemical data, it seems that volcanic rocks of the Qoyjeh Yeylaq area were formed from 5-20 % partial melting of a garnet- spinel lherzolite enriched mantle by subduction of Neo-Tethys under the central Iran, within the Orumieh- Dokhtar magmatic arc.
Petrology
Afsaneh Naseri-Esfandagheh; Mohammad Rahgoshay; Sasan Bagheri
Abstract
The Haji-Abad-Esfandagheh-Faryab ophiolitic belt is one of the most famous chromite-bearing occurrences in the south of Iran that has received considerable attention. Golashkard ultramafic unit includes dunite, highly serpentinized harzburgites, chromitite and wehrlite layers in the Faryab ophiolitic ...
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The Haji-Abad-Esfandagheh-Faryab ophiolitic belt is one of the most famous chromite-bearing occurrences in the south of Iran that has received considerable attention. Golashkard ultramafic unit includes dunite, highly serpentinized harzburgites, chromitite and wehrlite layers in the Faryab ophiolitic complex located in the southeast of Sanandaj-Sirjan as one of the chromite-bearing areas of the Haji-Abad-Esfandagheh-Faryab ophiolitic belt. Ultramafic rocks and chromitites of Golashkard area consist of 20 to more than 50% of chromite. The studied chromites have variable massive, banded and scattered textures. The geochemistry of Golashkard ultramafic rocks shows that the average Cr# enrichment of chromite in serpentinite rocks (probably dunite and harzburgite) and wehrlite is to Cr/ (Cr + Al) ×100= 70-80 and in chromitite is relatively higher (Cr/ (Cr + Al) ×100= 81). Based on the lithological and mineral chemistry characteristics, Golashkard ultramafic rocks are part of mantle related to ophiolite, which was produced by a homogeneous boninitic melt in the suprasubduction zone and formed high chromium chromitites and related peridotites.
Geophysics
Asghar Rastbood; Mohsen Sahebi-Ilekhchi
Abstract
Very Long Baseline Interferometry (VLBI) is one of the essential approaches in geodesy. Significant capabilities of this technique are creation of International Celestial Reference Frame (ICRF), determination of Earth orientation parameters (EOPs), coordinates of station with high accuracy and light ...
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Very Long Baseline Interferometry (VLBI) is one of the essential approaches in geodesy. Significant capabilities of this technique are creation of International Celestial Reference Frame (ICRF), determination of Earth orientation parameters (EOPs), coordinates of station with high accuracy and light deflection. Many attempts could be done to increase accuracy of VLBI data, including technical improvement of equipment, physical models improvement, using optimal data processing methods and increasing number of stations. In this study, in order to reduce the error of EOPs in CONT17 campaign, the appropriate position for a VLBI station in the Middle East is investigated. The results showed that mean error of EOPs in the Legacy-1and Legacy-2 reduced approximately 6.64% and 13.86% by adding two stations in Oman and Egypt countries, respectively.
Sedimentology
Alireza Vaezi; Vahid Tavakoli; Abdolmajid Naderi-Beni
Abstract
In the present study, in order to reconstruct the paleoenvironmental and climatic changes of Jiroft during the last 4000 years, several evidences of sedimentology and biogeochemistry on a sedimentary core have been investigated. Around. 3950 cal yr BP, low values of Ti/Al, Si/Al, C/N and CPI along with ...
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In the present study, in order to reconstruct the paleoenvironmental and climatic changes of Jiroft during the last 4000 years, several evidences of sedimentology and biogeochemistry on a sedimentary core have been investigated. Around. 3950 cal yr BP, low values of Ti/Al, Si/Al, C/N and CPI along with high values of δ13COM, and Paq indicate a wet period in Jiroft. evidence indicates a relative decrease in humidity between about 3900 and 3293 cal yr BP. Between 3293 and 2897 cal yr BP, Jiroft was dry and dusty. The results show very dry conditions with a significant increase in the amount of dust around 3200 cal yr BP. A long-wet period from about 2897 to 2302 cal yr BP can be recognized with high Paq values. The highest Ti/Al values along with the lowest δ13COM values indicate increased wind activity and dry conditions between 2100 and 1650 cal yr BP. Jiroft experienced wet conditions between 1540 and 1315 cal yr BP. With the relative decrease of rainfall, a semi-humid climate prevailed in Jiroft between 1315 and 854 cal yr BP.
Tectonics
Esmail Farahzadi; Seyed Ahmad Alavi; Mohammad Reza Ghassemi; Shahram Sherkati
Abstract
AbstractUnderstanding the history of uplift and folding in an area helps inferring the history of hydrocarbon genesis,migration and trapping and reducing exploratory drilling risks.Thermal model along with structural cross sections help understanding of this history and future plannings for ...
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AbstractUnderstanding the history of uplift and folding in an area helps inferring the history of hydrocarbon genesis,migration and trapping and reducing exploratory drilling risks.Thermal model along with structural cross sections help understanding of this history and future plannings for new exploration. In this paper we have used 3Dseismic reflective lines and geological maps to construct a regional balanced cross section and restore it in several stages. Combining of this cross section and a thermal model produced using vitrinite reflectance and apatite fission track, the history of exhumation and regional erosion is evaluated. Based on the results,unlike the Hormuz Series,the thickness of the Paleozoic sequence is equal throughout the region. This shows that the sedimentary-tectonic events have been the same in this period. The apatite fission track data indicate that the average time of rocks cooling is between14and24 million years ago (Late Oligocene-Middle Miocene).Based on the burial history graph, exhumation rate of the basement decrease from High Zagros to Abadan plain that show the basement in the northern part is involved in deformation earlier than in the southern part of the region. This involvement has affected the formation of structure,change of the sedimentary facies and the regional erosion pattern.
Economic Geology
Kourosh Shabani; Nima Nezafati; Morteza Momenzadeh; Mohammad Hashem Emami; Seyed Jamal Shaykhzakaryaii
Abstract
The Tareek Darreh gold Gold & Copper deposit is located 40km north of Torbat- e Jam in the Khorasan-Razavi province,NE-Iran. The study area is mainly comprised of slightly metamorphosed, sedimentary rocks of Jurassic age including alternation of shale, siltstone, and sandstone. These rocks have been ...
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The Tareek Darreh gold Gold & Copper deposit is located 40km north of Torbat- e Jam in the Khorasan-Razavi province,NE-Iran. The study area is mainly comprised of slightly metamorphosed, sedimentary rocks of Jurassic age including alternation of shale, siltstone, and sandstone. These rocks have been intruded by plutonic rocks such as gabbronorite, diorite, quartz-diorite, and rhyodacite. The ore bodies are exposed by trenching and pitting. The alteration minerals quartz, chlorite, albite, and sericite which are observed mostly on the top or margin of the stocks. Alteration is more intensive at the contacts of the stocks where vein type mineralization has occurred. The veins are mainly composed of silica type and calcite type, arsenopyrite, chalcopyrite, and pyrite main ore minerals. Probably more than 2-stages telescopic mineralization occurred in these zones and the conditions of temperature and pressure, as seen below. Appears to be a continuation of tectonic activity in the same place as intrusive and a little later the main cause of this phenomenon. According to our studies, The Tareek Darreh gold deposit is considered to be similar to the "intrusion-related gold "type.
Tectonics
Zahra Tavazo; Ebrahim Gholami; Hossien Motamedi; Bahman Soleimany
Abstract
Numerous mechanisms are active during folding in folded-thrust belts, such as the role of salt movement, the role of multiple detachments in sedimentary cover, interference between different phases of deformation, and the role of basement during folding. The performance of these mechanisms plays an important ...
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Numerous mechanisms are active during folding in folded-thrust belts, such as the role of salt movement, the role of multiple detachments in sedimentary cover, interference between different phases of deformation, and the role of basement during folding. The performance of these mechanisms plays an important role in the formation of different structures and geological features in geological units and folds geometry. In this research, such structures have been introduced and studied in Takhteh, Nahreh and Kuh-e-Lar anticlines in the north of Fars Paleo-High during field observations and measurement of geometric features of anticlines such as Aspect ratio, axial distance and half wavelength. These structures mainly include growth strata, geometry of tectonic synchronous strata, structures associated with shallow detachment such as rabbit ear structures, faults that are themselves structures that control the geometry and kinematics of structures, and sulfur springs that related to faults and rheology of exposed formations. The present study shows that the anticlines have an aspect ratio less than ten and are part of the detachment folds in which the detachment horizons have played a role and have a dextral arrangement. The formation of these anticlines occurred at the same time, which will be connected to each other, and these anticlines are associated with basement faults. The location of these anticlines is suitable for the presence of hydrocarbons but the basement fault in the southern flank of Takhteh anticline may affect the reservoir. The presence of water gaps and wind gaps in the region is a sign of uplift and activity of the region.
Exploration and Mining
Mehdi Talkhablou; Mehdi Kianpour; Seyed Mahmoud Fatemi Aghda
Abstract
In this study, the efficiency of the compressive wave velocity (Vp) geophysical method for predicting the quality of limestone mass in areas of Zagros formation, has been investigated. For qualitative classification of limestone rock masses, the Q classification system and its modified classification ...
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In this study, the efficiency of the compressive wave velocity (Vp) geophysical method for predicting the quality of limestone mass in areas of Zagros formation, has been investigated. For qualitative classification of limestone rock masses, the Q classification system and its modified classification system for sedimentary rocks (Qsrm) have been used. For this purpose, the data related to Vp, Q and Qsrm were extracted at the site of Karun 2, Karun 4, Khersan 3 and Tangeh Manshoureh dam sites and by using software interpolation methods in ArcGIS has been transformed into information layers. Using simple and multivariable regression analysis on data extracted from information layers and using Fuzzy Inference System (FIS), models for predicting Q and Qsrm in calcareous rock masses are presented. Also, to evaluate the accuracy of the obtained models, in addition to R2, performance indicators (VAF) and root mean square error (RMSE) were used. The results show that since the Qsrm index considers a wider range of massive properties, the prediction of the Qsrm value is closer to reality using geophysical methods than the Q index.
Petrology
hojjat hajhassani; Jalil Ghalamghash; Mansour Vousoughi Abedini; Rahim Dabiri; Hamideh Rashid
Abstract
The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They ...
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The leucocratic granite emplaced as small masses and dykes in the Alvand batholith. The leucocratic granite consists of tourmaline alkali granite, biotite alkali granite, arfvedsonite alkali granite, rutil alkali granite, and biotite- muscovite granites with alkaline and peraluminous affinities. They show enrichments of LREEs relative to HREEs and LILE relative to HFSE with negative anomalies in Nb, Ta and Ti, in normalized trace element diagrams. The leucocratic granite of the Alvand batholith resemble A-type and can be further classified in two of A and A' types granite. The trace elements content of A-type is much higher than A'-type granite. Based on geochemical data, it seems that A- and A'-type granites were generated from partial melting of mantle source. As mantle magma ascends, fractionate and empalce into the crust, A-type leucocratic are formed with minimal contamination and A'-type leucocratic with significant contaminant with continent crust are formed. Field and geochronology data suggest that the leucocratic granite were generated in the late Jurassic, which is contemporaneous with the subduction of the Neo-Tethys oceanic crust beneath the central Iran. It seems that the leucocratic granites were emplaced during a local extensional phase as dykes and small bodies in the Alvand batholith.
Geophysics
safieh farrokhi mogaddam; Abbas Alli Alli akbari bidokhti; Farhang Ahmadi givi; Mojtaba Ezam
Abstract
Salinity and water temperature are considered as important characteristics of water of different seas. The absolute values and variability of them in time and space determine life sustainability conditions, development of plants and animals and also types of human activity in seas. Water temperature ...
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Salinity and water temperature are considered as important characteristics of water of different seas. The absolute values and variability of them in time and space determine life sustainability conditions, development of plants and animals and also types of human activity in seas. Water temperature and salinity are important because of their effects on chemical and biochemical reactions of hydro-organisms. In this research the effects of climate change on physical characteristics of Persian Gulf including water temperature and salinity has been studied using numerical simulations and some observations. To carry out numerical simulation, the 1-dimension oceanic numerical model PROBE was used. The input data of the model includes meteorological information obtained from ECMWF and also initial values of the station. To simulate the vertical turbulence, the relations of Axcell-Liungman, Omstedt, Rodi, Pacanovski and Marchuk have been used for a station in the Persian Gulf and the results have been compared with some measurements and similar studies. The results of investigations show that limits of seawater and salinity variability model outputs are similar but the Omstedt relation shows more detailed changes in comparison to the others. The numerical results indicate that the temperature increase of the Persian Gulf over a decade can be as large as one to two degree Celsius, with some salinity increase as well.
Remote Sensing
mohammad sharifikia; jalal karami; Ehsan Falahati
Abstract
Optical Remote Sensing is a low-cost and efficient method to alteration zone detection. However in the area that have been covered by vegetation or alluvial, the identification of these areas is not very accurate with optical images. In this study fusion and integrating of ALOS-PALSAR L-band and ASTER ...
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Optical Remote Sensing is a low-cost and efficient method to alteration zone detection. However in the area that have been covered by vegetation or alluvial, the identification of these areas is not very accurate with optical images. In this study fusion and integrating of ALOS-PALSAR L-band and ASTER data by HSV, HSL, Maximum Likelihood and Artificial Neural Network has been done to discover and enhance the Argilic and Propylitic Alteration zones over the west part of Qazvin province in IRAN. For this purpose, Argilic and Propylitic alterations were primary identified unseeing ASTER image. Then based on geological data and field study, some areas with alterations covered by quaternary sediments, not detectable by ASTER images, were identified. In the following, the integration of the ALOS PALSAR L-band data and the ASTER SWIR bands with HSV, HLS, Maximum Likelihood and Artificial Neural Network were performed. The results of this study showed that the radar and optics data fusion, using HSV and HLS methods, increases the enhancement of visible argillic alteration zones in the study area. Also, the integration of radar and optics data with the Maximum Likelihood and the Artificial Neural Network methods,
Petrology
Seyed Mohsen Kashfi; Saeed Alirezaei; Mohammad Reza Hosseini; Iraj Rasa
Abstract
The Zaghdareh area in the Esfandagheh-Faryab ophiolitic complex, southern Sanandaj-Sirjan belt, embraces extensive outcrops of mafic-intermediate lava flows and a felsic intrusive body. The volcanic rocks are calc-alkaline to tholeiitic, metaluminous, and distinguished by depletions in light rare earth ...
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The Zaghdareh area in the Esfandagheh-Faryab ophiolitic complex, southern Sanandaj-Sirjan belt, embraces extensive outcrops of mafic-intermediate lava flows and a felsic intrusive body. The volcanic rocks are calc-alkaline to tholeiitic, metaluminous, and distinguished by depletions in light rare earth elements and relatively flat patterns for heavy rare earth elements in chondrite-normalized diagram; the (La/Yb)N ratio is lower than unity for most samples. The chemical attributes for the Zaghdareh volcanic rocks are comparable to those developed in suprasubduction zones. The Zaghdareh intrusive body is distinguished by abundant plagioclase and quartz, and subordinate hornblende, phenocrysts in quartz-feldspar rich matrix. Representative samples from the intrusion plot in the trondhjemite-tonalite fields in the normative An-Ab-Or diagram. The intrusion is calc-alkaline to tholeiitic, peraluminous, and marked by enrichments in Na2O and CaO and depletions in K2O, Rb, and most other LILEs, as well as low K2O/ Na2O ratios, very low Rb/Sr ratio, and distinct depletions in light rare earth elements, which are typical of the oceanic plagiogranites. Results from this study and a comparison with other ophiolitic suites in Iran suggest that the occurrence of plagiogranites is a recurring feature associated with the development and evolution of ophiolitic suites in suprasubduction zones.
Economic Geology
Mohsen Rezaei; Alireza Zarasvandi; Sima Basious
Abstract
Iju porphyry deposit is associated with the emplacement of Miocene tonalite-granodiorite intrusions (zircon U/Pb dating; 9.27±0.50) within Eocene volcanic and pyroclastic sequences including andesite, basaltic andesite, trachyandesite, andesitic breccias, tuffaceous breccias, and agglomerate. ...
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Iju porphyry deposit is associated with the emplacement of Miocene tonalite-granodiorite intrusions (zircon U/Pb dating; 9.27±0.50) within Eocene volcanic and pyroclastic sequences including andesite, basaltic andesite, trachyandesite, andesitic breccias, tuffaceous breccias, and agglomerate. In this study, occurrence and chemistry of magnetites in the potassic alteration of Iju deposit were assessed using EMPA analysis. The findings imply for a limited occurrence of magnetite as fine-grained disseminated and/or product of biotite chloritization. Magnetites associated with potassic alteration of Iju deposit don’t show hematite intergrowth (as martitizied margin) and anhydrite paragenesis, indicating the lack of high oxygen fugacity (near magnetite-hematite buffers; ~ΔFMQ+4) during the magnetite crystallization in the potassic alteration. Studied magnetites are high temperature (>500 °C) and according to the Mg + Al + Si contents crystallized under low rate of fluid rock interaction. These evidences accompanied with the absence of reequilibration processes could imply for the lack of repeated stages of hydrothermal fluid exsolving during the evolution of potassic alteration in the in the Iju deposit. Additionally, results represent that there are considerable values of Ga (average; 0.015 wt. %) in the studied magnetites providing insights into the presence of unseen exploration potentials associated with porphyry Cu deposits of UDMB.
Tectonics
Fereshteh Jafari-Hajati; Maryam Agh-Atabai; Majid Nemati; Ali Biglari-Fadafan
Abstract
In this research, to understand the present-day tectonic situation of Gorgan-plain in the east of the South Caspian basin, the tectonic stress regime of this area and its adjacent areas was estimated using the inversion of the data of the earthquake focal mechanisms. For this aim, in addition to analyzing ...
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In this research, to understand the present-day tectonic situation of Gorgan-plain in the east of the South Caspian basin, the tectonic stress regime of this area and its adjacent areas was estimated using the inversion of the data of the earthquake focal mechanisms. For this aim, in addition to analyzing focal mechanisms solved by different sources, the focal mechanisms were solved for several earthquakes with appropriate and sufficient information. The results indicate the presence of various mechanisms, including thrust, normal, and strike-slip, and as a result, various orientations of kinematic P and T axes, which can indicate the complexity of the region. By analyzing the earthquakes with a minimum magnitude of 4 in the Gorgan-plain, the Kopeh-Dagh in the east of the plain, and the entire eastern region of the South Caspian, a compression regime with a NNW-SSE trend was obtained. However, by analyzing all of the earthquakes (smaller and larger earthquakes) in the Gorgan-plain, a strike-slip regime was obtained, in which the trend of the P and T axes were calculated NE-SW and NW-SE, respectively. The results indicate a local strike-slip regime in addition to the regional compressional regime in the region.
Economic Geology
Z. Zandi; A. R. Jafari rad; A. Gourabjeripour; M. Lotfi
Abstract
The Saheb Fe-Cu skarn deposit is located in the Sanandaj-Sirjan metamorphic belt, SE Saqqez, western Iran and has been formed along the contact between the Oligo-Miocene aged Saheb granitoid and the Permian aged impure calcareous rocks and includes endoskarn and exoskarn. Exoskarn is widely developed ...
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The Saheb Fe-Cu skarn deposit is located in the Sanandaj-Sirjan metamorphic belt, SE Saqqez, western Iran and has been formed along the contact between the Oligo-Miocene aged Saheb granitoid and the Permian aged impure calcareous rocks and includes endoskarn and exoskarn. Exoskarn is widely developed and include garnet and epidote skarn zones. The majority of mineralized zones are concentrated in garnet skarn. The relatively oxidizing mineralogical assemblage of the Saheb skarn includes garnet (andradite-grossular), pyroxene (diopside-hedenbergite), magnetite and hematite. Magnetite is the main and abundant ore mineral throughout the ore deposit. Based on field evidences and microscopic studies of skarn zone samples, two stages of prograde and retrograde alteration are distinguishable. According to the results of sample analysis of Saheb skarn productive intrusive body by XRF and ICP-MS techniques, the combination of this body is chiefly granite to granodiorite-diorite and belong to the I-type granitoids, metaluminous and K-rich calc-alkaline series. The Saheb granitoid is related to the VAG (Volcanic Arc Granite) tectonic setting.
Petroleum geology
Majid Safaei Farouji; Hosein Rahimpour- bonab; Mohammadreza Kamali; Buyuk Ghorbani
Abstract
Geochemical investigation of Kazhdumi and Pabdeh formations suggest a shaly and carbonate lithology as well as a suboxic-anoxic marine depositional environment for both formations. On the other hand, the thermal maturity of the Kazhdumi Formation is equivalent to the mid of oil window while thermal maturity-related ...
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Geochemical investigation of Kazhdumi and Pabdeh formations suggest a shaly and carbonate lithology as well as a suboxic-anoxic marine depositional environment for both formations. On the other hand, the thermal maturity of the Kazhdumi Formation is equivalent to the mid of oil window while thermal maturity-related parameters show that the Pabdeh Formation has not entered the oil window. Biomarkers are indicative of derivation of the four oil samples from a carbonate-shaly or marly source rock. Also, thermal maturity-related biomarkers reflect a peak mature stage for all of the four samples. Different values of oleanane index in oil samples is implying a more significant role of the Pabdeh Formation in hydrocarbon embedded in 36, 56, 55 wells in compare to well number 22. In general, oil-source correlation introduces both Kazhdumi and Pabdeh formations as source rocks for the crude oils.
Petrology
Mohammad Saadat; Robab Hajialioghli; Mohssen Moazzen
Abstract
The Qotur metamorphic complex in west of Khoy is consist of various metamorphic rocks including of metabasites, metapelitic and meta-calcareous rocks and serpentinites. The metagabbros form main outcropping rocks in the area. Plagioclase and pyroxene are the main porphyroclasts of metagabbros. Epidote, ...
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The Qotur metamorphic complex in west of Khoy is consist of various metamorphic rocks including of metabasites, metapelitic and meta-calcareous rocks and serpentinites. The metagabbros form main outcropping rocks in the area. Plagioclase and pyroxene are the main porphyroclasts of metagabbros. Epidote, tremolite/actinolite, calcite and chlorite are formed during low grade metamorphism of these rocks. Based on geochemistry results, protolite compositions of the investigated rocks are plotted on the gabbroic field of the classification diagram. They have calc-alkaline magmatic series. Considering the discrimination tectonic diagrams the Qotur metagabbroic rocks have been formed at the island arc tectonic setting. On the basis of U-Pb zircon geochronological data, the rocks are formed at 162.6±7.6 Ma corresponds to the late Jurassic (Oxfordian). On the basis of results obtained from isotopic dating and geochemical data of the Qotur metagabbros, we suppose that they formed related to the sialic back arc basin of Neotethys, Jurrasic Island arc rocks of Sevan-Akera zone corresponds to the North branch of Neotethys oceanic suture and/or in continuation of the Piranshahr and Serow ophiolites as a Zagros-Bitlis Zone. However perecise results will be need to tectonic works and more geochemical and isotopic data from variety of metamorphic and igneous rocks.
Hydrology
Soraya Nouri -Sangarab; Asghar Asghari - Moghaddam; Nasser Jabraeeli-Andrian
Abstract
Recently, due to the trend of decreasing rainfall and increasing groundwater pumping rate, there have been concerns about the risks caused by the decrease in the volume of aquifer reserves and the drop in the groundwater level, and as a consequence the land subsidence. Also, in Ajabshir plain due to ...
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Recently, due to the trend of decreasing rainfall and increasing groundwater pumping rate, there have been concerns about the risks caused by the decrease in the volume of aquifer reserves and the drop in the groundwater level, and as a consequence the land subsidence. Also, in Ajabshir plain due to a gradual decrease in the water level, it is necessary to estimate the subsidence and investigate the subsidence potential to prevent its harmful risks in the future. For this purpose, using the ALPRIFT framework, which includes seven layers of parameters affecting subsidence, the subsidence potential map was zoned. The subsidence potential index was obtained in low and moderate ranges. In the next step, using Sentinel-1 satellite images, the subsidence during the years 2020-2021 was estimated to be 2.4 cm, which had a significant correlation with the groundwater level of the water year 2020-2021 and subsidence potential. In addition, artificial intelligence optimization methods including fuzzy logic (Sugeno) and genetic algorithm were used in order to fix the defects of applying expert opinions and increase the correlation between subsidence (Insar) and ALPRIFT, among these models, Sugeno's fuzzy method provided the best correlation between the two subsidence maps and ALPRIFT. The correlation between subsidence with ALPRIFT, ALPRIFT-GA and ALPRIFT-SFL was obtained as 0.46, 0.62 and 0.72 respectively.
Economic Geology
Almasi Alireza; Ghasem Nabatian; Amir Mahdavi; Qiuli Li
Abstract
The Maher abad and Khopik porphyry Cu deposits occurred in the Upper Eocene (39-37 Ma) in Lut block. All of them associated with intermediate (mostly monzonite) rocks. Porphyry deposits are closely associated with oxidized magmas. Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry ...
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The Maher abad and Khopik porphyry Cu deposits occurred in the Upper Eocene (39-37 Ma) in Lut block. All of them associated with intermediate (mostly monzonite) rocks. Porphyry deposits are closely associated with oxidized magmas. Oxygen fugacity (fO2) is a key factor that controls the formation of porphyry Cu deposits. The composition of the major and trace elements of zircon grains related to several ore-bearing monzonite were measured in Maher abad and Khopik porphyry copper indices. Zircon grains show moderate to low Ce4+/Ce3+ with a range of 19 to 610 and an average of 155. The average of oxygen fugacity (logfO2) values of Meher abad and Khopik ore-bearing magmas, range ∆FMQ -3.2 to MFMQ -1.3 with mean ∆FMQ -2.2, indicate formation under moderate oxidation conditions (between Ni-NiO (NNO) and Faylite magnetite-quartz (FMQ) buffers, but magnetite-hematite (HM) buffer, which ), which is not ideal for the formation of porphyry deposits. This is supported by whole-rock and Sr-isotopic data, and absence of high oxidation minerals such as hematite, and the poor adakitic charactristic of rocks in both deposits, which are due to factors involved in magma origin such as rock type and partial melting rate (possibly peridotite with low participation of slab).
Petrology
Mohammad reza Ghasempour; Nahid Shabanian; alireza Davoudian; hasamaldin moeinzadeh
Abstract
The Horjand area is located in northeast of Kerman in the Central Iran zone and the Kashmar-Kerman tectonic belt. In this area, gabbroic rocks and doleritic dykes are intruded into the sedimentary rocks of Desu Series with Infra-Cambrian age. The gabbros and doleritic dykes have relatively same composition. ...
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The Horjand area is located in northeast of Kerman in the Central Iran zone and the Kashmar-Kerman tectonic belt. In this area, gabbroic rocks and doleritic dykes are intruded into the sedimentary rocks of Desu Series with Infra-Cambrian age. The gabbros and doleritic dykes have relatively same composition. The main minerals are plagioclase and clinopyroxene. Their texture is medium to fine granular and ophitic to sub-ophitic. The plagioclase minerals of the rocks have labradorite composition (An53-67), but as a result of saussuritization in gabbros and doleritic dykes, the plagioclase changed to oligoclase and albite composition, respectively. The mineral chemistry of clinopyroxenes display Mg-Ca-Fe type which are diopside and augite. The distribution of aluminum in clinopyroxenes structure show that the minerals were crystallized from a magma with water vapor pressure less than 10 percent. On the basis of the chemical charaterstions of the clinopyroxenes, the magma source has predominantly had tholeiitic to minor alkaline affinities with a tectonic setting related to within plate environments. Geothermobarometry evaluations of the clinopyroxenes reveal that the mafic rocks were formed at temperatures of 1127-1200 ˚C and pressure less than 6 Kbar.
Sedimentology
Hadi Amin-Rasouli; Nasim Haghighat jou; Mahdi Moradi
Abstract
Kraftu cave, 67 km northwest of Divandareh in Kurdistan province, includes four floors. The bottom of the second floor, in the bat hall, is covered by thick guano deposits. SEM–EDX analyses of the guano deposits showed secondary sulfate (gypsum, cesanite), phosphate (phosphammite, brushite, taranakite, ...
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Kraftu cave, 67 km northwest of Divandareh in Kurdistan province, includes four floors. The bottom of the second floor, in the bat hall, is covered by thick guano deposits. SEM–EDX analyses of the guano deposits showed secondary sulfate (gypsum, cesanite), phosphate (phosphammite, brushite, taranakite, francoanellite, whitlockite, leucophosphite, spheniscidite, pyrocoproite), and nitrate (urea, niter) minerals, along with microorganisms and chitin. Occurrence of these minerals is due to changes in the pH (from acidic to alkaline) and moisture (wet and dry conditions) in the presence of microorganisms. Bat guano has accumulated in Karaftu cave during three different paleoclimate conditions, from base to top, including dry, wet, and dry conditions. A comparison between distributions of secondary minerals and Ce-anomalies along the profile represents that taranakite only forms in wet conditions, but whitlockite, urea, and cesanite only occur in dry ones. Therefore, they are significant indicators of climate in the geologic record, but other minerals, because they can be in both conditions, don't be so.Various reactions between the solutions derived from guano with substrate have resulted in phosphatization and dolomitization of bedrock. The abundance of chitin in the Karaftu cave guano deposits indicates that they are feces of insectivorous bats.
Petrology
Nargess Shirdashtzadeh; Ghodrat Torabi
Abstract
In this study, some mantle lherzolites of Ashin ophiolite are investigated which contain evidence of a geotectonic/metamorphism during exhumation and obduction of oceanic lithosphere on the continental crust, after closure of Neo-Tethys Ocean. Based on petrography, their primary rock-forming minerals ...
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In this study, some mantle lherzolites of Ashin ophiolite are investigated which contain evidence of a geotectonic/metamorphism during exhumation and obduction of oceanic lithosphere on the continental crust, after closure of Neo-Tethys Ocean. Based on petrography, their primary rock-forming minerals are orthopyroxene, clinopyroxene, olivine, and chromian spinel. Mineralogy and geothermobarometry indicate that these 4-phase lherzolites were formed in the lithospheric mantle (at pressures ~ 21.6 to 8.6 kbar) by melt/wall rock reactions (at temperatures ~ 1012-1183 °C). Then, they were emplaced and obducted on the continental crust along the fault zone of this region, and consequently deformed. The first ductile deformation event occurred in the depth of lithosphere and resulted in high-temperature mylonitization at temperatures higher than 600 to 800 °C. Mineralogical features confirm pressure decreasing of this stage by subsolidus reaction of pyroxene and spinel and substitution of plagioclase and olivine. Therefore, petrography and thermobarometry data are indicative of the spinel to plagioclase lherzolite facies for these rocks. Finally, they partially underwent brittle and cataclastic deformation at temperatures below 600°C and lower pressures and depth during exhumation. However, most of plagioclases were replaced by with prehnite, pumpellyite, chlorite, hydrogrossular and xonotlite minerals by further alterations.
Petrology
kiamars hosseini; Majid Shahpasandzadeh
Abstract
The Late Neoproterozoic-Early Cambrian albite-bearing metasomatite, rhyolites and rhyodacites predominantly constitute the host rocks of the Choghart magnetite-apatite deposit in Central Iran. The geologic evidences show three types of albites in the host albite-bearing metasomatite. The performed mineralogical ...
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The Late Neoproterozoic-Early Cambrian albite-bearing metasomatite, rhyolites and rhyodacites predominantly constitute the host rocks of the Choghart magnetite-apatite deposit in Central Iran. The geologic evidences show three types of albites in the host albite-bearing metasomatite. The performed mineralogical and geochemical investigations display enrichment of REE-Y-Ti-Th in the pink and fleshy red albites, whereas the white albites are barren without any ore mineralization. The concentration of REE-Y-Ti-Th-U bearing minerals along the fractures, the variation of Th/U ratio and result of stable isotopes studies of the calcites syn-paragenesis with the abiltes reveal the involvement of mixed magmatic and high-midium temperature hydrothermal processes play an important role in the ore genesis. The similarity pattern of the REEs and trace elements in different types of abilte-bearing metasomatite and rhyolite manifest the origin of REE-Y-Ti-Th mineralization as the rhyolitic-rhyodacitic magmas, related to a continental/oceanic subduction zone. According to this research, tectono-magmatic setting of the albite-bearing metasomatite in the Choghart deposit is suggested as a Calc-alkaline magmatism, associated with the active continental margin and oceanic island arcs.
Geological Environment and Engineering
Shirin Samani; Ali Uromeihy; Amirhossein Enayati; Imandokht Mostafavi; Misha Pezeshki
Abstract
Diagenetic processes in carbonate rocks can be considered as one of the most important factors influencing the inherent characteristics of this type of reservoir on a small as well as large scale. Considering the importance of knowing the mechanical characteristics of reservoir rocks in geomechanical ...
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Diagenetic processes in carbonate rocks can be considered as one of the most important factors influencing the inherent characteristics of this type of reservoir on a small as well as large scale. Considering the importance of knowing the mechanical characteristics of reservoir rocks in geomechanical modeling and its application in the exploitation and development of hydrocarbon fields, it is necessary to find out how lithological characteristics affect its rock mechanical behavior. In this study, the impact of two diagenetic processes (Dolomitization and Anhydrite cement) on the physical and mechanical characteristics (such as Uniaxial Compressive Strength, Young’s modulus, Cohesion, and Internal friction angle) of carbonate reservoirs of the Kangan Formation, are addressed. The evaluations have been done in two phases: i.e., lithological studies and rock mechanical tests. The results show that changes in mechanical properties are strongly influenced by diagenetic processes. The two main influential features on mechanical characteristics are dolomitization and anhydrite cementation, which strongly affect porosity, dominant pore type, and mineralogy. The results show that dolomitization in the studied samples has caused an increase in porosity and a decrease in strength and elasticity. While the presence of anhydrite has caused an improvement in the resistance characteristics with an opposite effect.
Exploration and Mining
Ahmad Adib; Peyman Afzal
Abstract
In this research, the leaching of REEs from the tailing of the apatite-iron ore processing unit of Morvarid mine (NW Iran), has been investigated using nitric, hydrochloric and sulfuric acids. This tailing contains rare earth elements (REEs) specifically Ce, La, Nd, Y and its accompanying minerals are ...
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In this research, the leaching of REEs from the tailing of the apatite-iron ore processing unit of Morvarid mine (NW Iran), has been investigated using nitric, hydrochloric and sulfuric acids. This tailing contains rare earth elements (REEs) specifically Ce, La, Nd, Y and its accompanying minerals are magnetite, apatite, monazite, hematite, quartz. The appropriate dimensions for apatite release are 80-75μm. Leaching tests were performed for all three acids, and digestion process was also used for sulfuric acid. The leaching in the presence of sulfuric acid, under a temperature of 90°C, an acid concentration of 40% and a time of 60 minutes, leads to the total recovery of REE equal to 40.23%, and in acid sulfuric acid digestion at 200°C, equal to 61.21%. became. The recovery of REE when using hydrochloric acid at 72.64°C, concentration of hydrochloric acid 36.21% and time 56.28 minutes, was equal to 60.57%. In the presence of nitric acid, under the optimal conditions of temperature 61.51°C, acid concentration 40% and time 72.92 minutes. Furthermore, the maximum recovery of total REE equal to 51.9% was obtained. Due to the higher recovery and the lower price of sulfuric acid, this method is suggested for extracting for the extraction of REEs from the tailings.
