Original Research Paper
Petroleum geology
Abstract
In the northern border of Arabian plate exist a complex reverse fault zone in parallel to the Main Zagros Revers Fault. In spit of them, it could be observed another younger fault with dextral strike-slip nearly parallel to the Main Zagros Revers Fault. The young fault is called Main Recent Fault; MRF ...
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In the northern border of Arabian plate exist a complex reverse fault zone in parallel to the Main Zagros Revers Fault. In spit of them, it could be observed another younger fault with dextral strike-slip nearly parallel to the Main Zagros Revers Fault. The young fault is called Main Recent Fault; MRF which shows clear evidences on the surface. The MRF contains many active segments with 100 km length in average from NW to SE which are Piranshahr, Marivan, Sartakht, Morvarid, Dinvar, Sahneh, Nahavand and Droud. Filed data indicates that MRF extended after Droud segment to the SE. They are called Kohrang and Ardal segments. Kohrang fault with 80 km length is separated as en echelon from Droud fault and is oriented with N140 degree trend from 33 north orbit to the Kohrang plain. Ardal fault with 120 km length separates form Kohrang fault. It ends to the SE with N-S trending dextral strike-slip Dena fault. At the end points of Kohrang Fault exist two salt diapirs. It suggests that a part of the segmentation is controlled by salt diapir due to age and mechanical property of sediments above and around of diapirs.
Original Research Paper
Exploration and Mining
Keytash Moshtaghian; Sayyed Mohammad Abtahi Forooshani; Hooshang Asadi Harooni; Mohammad Hajheidari; Ghazal Janghorban
Abstract
The Dalli porphyry Copper-Gold deposit consists of two northern and southern indexes located on the Urmia-Dokhtar Volcanic Belt in Markazi province. Due to the presence of magnetite beneath the potassic alteration zone in the center of porphyry mineralization, a magnetometric survey was performed in ...
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The Dalli porphyry Copper-Gold deposit consists of two northern and southern indexes located on the Urmia-Dokhtar Volcanic Belt in Markazi province. Due to the presence of magnetite beneath the potassic alteration zone in the center of porphyry mineralization, a magnetometric survey was performed in the region. In the current study in the northern index, first, we extracted the local anomaly via removing the regional and aliasing effects from the magnetic data. Then, using three-dimensional inverse modeling of the reducted data illustrates the presence of a body with high magnetic susceptibility, in the depth range of 40 to 640 meters of the study area. A comparison between geochemical analysis of two exploratory core drilling with the depth variational model of the estimated magnetic susceptibility in the study area indicates a spatial correlation between increases in the grades of copper and gold and large variations of the magnetic susceptibility. Also, comparison between the magnetic susceptibility model and resistivity and chargeability models estimated from IP/RS data of three parallel profiles indicates a relation between sulfidic and altered mineralized zones and magnetic susceptibility variations. Therefore, the current study shows a high potential for the copper-gold mineralization in the northern Dalli index.
Original Research Paper
Stratigraphy and Palaeontology
Parynaz rasoulighadi; Mehdi Sarfi; mohsen al-e-ali; zahra maleki
Abstract
Identification of key sequence stratigraphic surfaces is a crucial task in geological characterization of hydrocarbon reservoirs. The uppermost Jurassic–lower Cretaceous carbonate successions of the Manifa member and Fahliyan Formation are as an important oil reservoir of Northwestern Persian Gulf. ...
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Identification of key sequence stratigraphic surfaces is a crucial task in geological characterization of hydrocarbon reservoirs. The uppermost Jurassic–lower Cretaceous carbonate successions of the Manifa member and Fahliyan Formation are as an important oil reservoir of Northwestern Persian Gulf. Application of GR D-INPEFA Curve to discriminate and correlate key stratigraphic surfaces and sequences of the studied carbonates in five cored wells a giant oil field of the Persian Gulf. To achieve this goal, identified key stratigraphic surfaces of core and thin sections were compared with interpretation of GR D-INPEFA curve. From sequence stratigraphic point of view and based on the results from geological studies, the Late Tithonian-Neocomian sequence has been discriminated into four third-order sequences which are described and interpreted. The top sequence boundary of the Manifa carbonate corresponds to a significant discontinuity that facies above and below this important key surfaces show major facies variation. Based on the applied D-INPEFA curve, identified sequence of can be effectively discriminated in the field scale. The results of this study show that D-INPEFA is a successful, fast and easy approach for identification of main key stratigraphic surfaces when three is a good agreement between core derived surfaces and those identified D-INPEFA approach.
Original Research Paper
Economic Geology
monire sakhdari; Mehrdad Behzadi; M. Yazdi; Nematollah Rashidnejad Omran; Morteza Sadeghi Naeini
Abstract
The Godar Sorkh area is located in the central part of the Sanandaj-Sirjan zone, 20km southwest of the Muteh region. Gold mineralization at Godar Sorkh occurs in quartz-sulfide veins that hosted in metasedimentary rocks. Veins of mineralization typically formed along normal faults. Rock sequences are ...
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The Godar Sorkh area is located in the central part of the Sanandaj-Sirjan zone, 20km southwest of the Muteh region. Gold mineralization at Godar Sorkh occurs in quartz-sulfide veins that hosted in metasedimentary rocks. Veins of mineralization typically formed along normal faults. Rock sequences are affected by several deformation phase, gold mineralization occurs in ductile to ductile-brittle shear zones and had been under poly-phase metamorphism. The main alterations are Sulfidation, carbonization, silicification, chloritization, and sericitization. Ore-mineral assemblages include pyrite and chalcopyrite, arsenopyrite, sphalerite, galena, and Fe-oxide. Mean homogenization temperature in gold-bearing quartz range between 275oC and 300oC. Fluid inclusions in quartz veins are dominated by CO2-H2O-NaCl fluid. Salinity ranges from 9 to 17 wt. % NaCl equivalent. Corresponding to a depth of<2 km, Godar Sorkh deposit is formed in epizonal environment. Measured δ18O values for the gold-bearing quartz range between 12.7 to 14.3 permil, estimated δ18Ofluid values range from +6.4 to +7.3 permil, δ34S values range from –16 to +5 permil, and estimated δ34Sfluid values range from +4.2 to -17.3 permil. Fluid inclusion and stable isotope studies on ore-bearing quartz-sulfide veins indicating the major role of metamorphic fluids. Gold derived from metasedimentary rocks. Gold mineralization in the Godar sorkh deposit classified as an orogenic gold deposit.Keyword: Orgenic gold, Fluid inclusion, stable isotope, Godar Sorkh, Sanandaj-sirjan zone
Original Research Paper
Tectonics
Mohammad Reza Mazinani; Ali Yassaghi; Reaza Nozaem
Abstract
The E-W trending Faghan fault system with >180 km in length located in the northern part of the Lut Block and south of the Dorouneh Fault in central Iran. The fault cut through basement rocks and all other younger units from Cambrian to Cenozoic. Kinematic and dynamic analyses of the Faghan fault ...
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The E-W trending Faghan fault system with >180 km in length located in the northern part of the Lut Block and south of the Dorouneh Fault in central Iran. The fault cut through basement rocks and all other younger units from Cambrian to Cenozoic. Kinematic and dynamic analyses of the Faghan fault system is crucial for understanding the tectonic framework of the northern part of the Lut Block. These field based investigation analyses of the Faghan fault system indicates the E-W trending dextral strike- slip shear kinematics for the fault system and as Principal Deformation Zone (PDZ) along which minor sinistral, dextral and dip slip faults have also formed as second order riedel shears. Therefore, like the Kuh-e-Sarhangi fault zone, the Faghan fault system is considered as one of the fundamental fault zone in the north of the Lut Block caused the deformation partitioning in the block during Late Cenozoic. Accordingly, the Faghan fault system divorces the Bardacan-Kashmar and Gonabad micro-blocks from each other and transfers the deformation from the main Lut Block into its northern micro-blocks by Intraplate escaping tectonics.
Original Research Paper
mojgan Salehi Yazdi; Mansour Ghorbani; nima nezafati; mansor vosoghi abedini
Abstract
Takab-Mahneshan's metallogenic area is essential in gold mineralization, and it is a part of the northern Urmia-Dokhtar magmatic belt. The northern Urmia-Dokhtar has two distinctive features. It contains the Precambrian basement, and the young Mio-Pliocene magmatism rocks overlie its Precambrian basement. ...
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Takab-Mahneshan's metallogenic area is essential in gold mineralization, and it is a part of the northern Urmia-Dokhtar magmatic belt. The northern Urmia-Dokhtar has two distinctive features. It contains the Precambrian basement, and the young Mio-Pliocene magmatism rocks overlie its Precambrian basement. Precambrian basement has two different compositions, oceanic and continental crusts (gneiss, granite, mica-schist, greenschist, amphibolite, serpentinite, marble). The Young rocks are composed of hyaloclastite, acidic tuff, andesitic-basaltic, acidic to intermediate intrusions (diorite, granite), limestone, and marl of Qom formation. We categorized the Young rocks into four phases based on their age and positions. The mutual effect of the basement and young magmatism --in the latest phase --creates hydrothermal solutions in the form of a heat engine. The heat engine has caused rotation and variety, increasing mineralization in the area. As a result, there are mines, deposits, gold indications, and some associated gold elements, including Tuzlar, Bayche Bagh, Baghcheh at Mahneshan area, Zarshuran, Agh-darreh, and Ay-Qalesi in Takab. The Tuzlar and Baghcheh deposits with gold mineralization are in a Silicic-argillic zone, including pyrite, gold-bearing silica, argillic and ferrous hydroxides minerals. The Ay-Qalesi polymetallic deposits often contain zinc and lead. The Zarshuran and Agh-darreh deposits are the gold types that the first one has a variety of mineralization of sulfides and sulfosalts. The second one has simple gold mineralization, and finally, the Bayche Bagh deposit with polymetallic type includes chalcopyrite, pyrite, rutile, arsenopyrite, sphalerite, bornite, smaltite, chloanthite, azurite, and malachite minerals.
Original Research Paper
Economic Geology
Mohammad Ali Rajabzadeh; mohammad amini
Abstract
This is report podiform chromite deposits associated with the Kurdistan ophiolite.These ore deposits with granular massive fabric are hosted by dunite and harzburgite occurred in south Marivan city.Chemistry of chromian spinel in the chromite deposits indicated that Cr# for two ore occurrences is high ...
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This is report podiform chromite deposits associated with the Kurdistan ophiolite.These ore deposits with granular massive fabric are hosted by dunite and harzburgite occurred in south Marivan city.Chemistry of chromian spinel in the chromite deposits indicated that Cr# for two ore occurrences is high (0.85) with very low TiO2, but for the other ore occurrence is lower (0.67) with higher TiO2 (0.05).This finding shows that the chromite ore deposits and consequently their host ophiolite were developed in two different geotectonical settings.Geochemical data indicated that some of the studied ore deposits occurred during the opening of oceanic crust in a Mid Oceanic Ridge setting from a tholeiitic magma while the others were fractionated form a boninitic melt in a Supra Subduction Zone.Range of gabbros host ilmenite, magnetite and titanite in three regions at northwest of Kamyaran,east of Sarvabad and south of Marivan.The chemical composition of the ilmenites showed that the average concentration of TiO2 increases from Kamyaran (43.19 wt.%) to Sarvabad (46.09 wt.%) and then to Marivan (47.42 wt.%).Based on textural and mineral chemistry evidence, mineralization of titanium occurred as the result of magma oxidation.The oxidation of magma resulted in the formation of iron-titanium immiscible liquid droplets, following the plagioclase crystallization.
Original Research Paper
Economic Geology
Nima Rahimi; Shojaedin Shojaedin Niroomand; Mohammad Lotfi; Mojtaba Rahimi Shahid
Abstract
The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous ...
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The Janja Cu-Mo porphyry deposit is located at 70 km south of the Nehbandan, Sistan suture zone, Eastern Iran. The porphyry mineralization in the Janja deposit is temporally and spatially associated with the diorite to quartz diorite and granodiorite granular to porphyry stocks that intruded in the Cretaceous flysch units. The main sulfide minerals consist of chalcopyrite, pyrite, covellite, chalcocite, molybdenite, bornite, and oxide minerals including magnetite, hematite, goethite and hydro carbonate minerals including malachite and azurite. Fluid inclusion studies showed a homogenization temperature range from 301 to 540 ˚C and a mean salinity of 19 wt%NaCl for two-phase inclusions and a homogenization temperature range between 254 and >550 ˚C and mean salinities of 54 wt%NaCl for multiphase fluid inclusions. The results of these studies show that boiling and mixing processes have taken place in the Janja deposit and have caused the deposition of Cu (Mo±Au) mineralization. Eventually, according to the various characteristics of the Janja deposit, including tectonic environment, host rock, mineralogy, ore-forming fluid, metal ore assemblage, mineralization and alteration patterns, and comparison of these characteristics with other porphyry deposits, it can be concluded that mineralization in Janja deposit is comparable with continental margin-type porphyry Cu-Mo-(Au) deposits.
Original Research Paper
Economic Geology
kiamars hosseini; Majid Shahpasandzadeh; Roghayeh zabihi khargh
Abstract
The Sangan Mining District (SMD) in the north of the Cenozoic magmatic belt of eastern Iran is constituted of predominantly acidic to intermediate volcanic and pyroclastic rocks, intruded by the Eocene granitoids. In the Baghak Fe skarn deposit, these granitoids are composed of pre-mineralization biotite ...
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The Sangan Mining District (SMD) in the north of the Cenozoic magmatic belt of eastern Iran is constituted of predominantly acidic to intermediate volcanic and pyroclastic rocks, intruded by the Eocene granitoids. In the Baghak Fe skarn deposit, these granitoids are composed of pre-mineralization biotite quartz monzonite, biotite syenite to biotite syenogranite, alkali feldspar quartz syenite to alkali feldspar granite and syn-mineralization quartz alkali syenite and quartz syenite. These I type granitoids have a magnesian metaluminous, calcalkaline, high K alkaline to shoshonitic nature. The granitoids show enrichment of LREE/HREE and LILE/HFSE with negative anomalies of Eu, Sr, Ta, Th and Ti, posetive anomalies of U, K, Ba, and Rb together with high La values and Zr/Nb, Nb/Th, Nb/U, and Nb/La ratios which suggest not only their slab-derived mantle source, but also crustal mixing in evolution of the magma. The Sm/Yb versus La/Sm, Sm/Yb versus Sm and Dy/Yb versus La/Yb show derivation of the primary melt from low partial melting (2-5 %) of a garnet-spinel lherzolite at depth of ~ 66-68 kilometers of the upper mantle, affected by continental crust melts. According to this research, the tectono-magmatic setting of the granitoids is suggested syn- to post-orogenic magmatic arc.
Original Research Paper
Economic Geology
Shahram Mobaser; taher farhadinejad; Abbas Asgari; Mohammad Ali Ali Abadi; shirin fatahi
Abstract
The Barzavand copper deposit with oligocene age located in 30 Km northeast of Zefreh along tension fault with W-E trend. Alteration in study area is stratabound form and mainly include: pyritization, propylitization, zeolitization, silicification, albitization and prehnitization of basaltic lavas. Furthermore ...
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The Barzavand copper deposit with oligocene age located in 30 Km northeast of Zefreh along tension fault with W-E trend. Alteration in study area is stratabound form and mainly include: pyritization, propylitization, zeolitization, silicification, albitization and prehnitization of basaltic lavas. Furthermore geochemical studies in Barzavand show enrichment of SiO2, Al2O3, K2O, Na2O, P2O5, TiO2, ∑REE, Ag, As, Ba, Be, Bi, Cd, Cs, Cu, Li, Mo, Nb, Pb, Rb, Sb, Se, Sn, Sr, Ta, Tl, Te, Th, U, W, Y, Zn, and Zr, enrichment- depletion of CaO, Fe2O3, MnO, Hf, Sc and V and depletion of S, Ni, Cr, MgO and Co during alteration. The positive correlation between (La/Lu)N, (La/Yb)N, (La/Sm)N and (La/Y)N and CaO (r= 0.70 to 0.96) indicate that propylitization of host rock basalt and increase in pH of fluid responsible mineralization that play important role in differentiation of lanthanides in study area. The Barzavand copper deposit has submarine volcanism, early and late diagenesis, burial metamorphism and weathering stages during its evolution. According to alteration properties, mineralogy and the Whole rock geochemistry can be said the Barzavand copper deposit is most similar to Manto type copper deposits.
Original Research Paper
Stratigraphy and Palaeontology
Mohammad Reza Esmaeilbeig; najmeh Nazeri Tahrudi; Mohammadreza Ghotbi Ravandi; Maryam naz Bahrammanesh tehrani
Abstract
Stratigraphic and paleontological studies on 6-section brachiopods from Lower to Upper Paleozoic in the Kerman region were performed by a joint Iranian-Italian team. In one of these sections in the Shabjareh area - Kerman - Kat Kouyeh Formation with geographical characteristics of 31º 5´ 56º, ...
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Stratigraphic and paleontological studies on 6-section brachiopods from Lower to Upper Paleozoic in the Kerman region were performed by a joint Iranian-Italian team. In one of these sections in the Shabjareh area - Kerman - Kat Kouyeh Formation with geographical characteristics of 31º 5´ 56º, 10E, N, a complete sequence of the rotation of Ordovician sediments that had brachiopods in some horizons was studied. One of the typical brachiopods studied is Martellia shabjerehansis. Ultrastructural studies on this species and studies to study the shell changes of brachiopods from Cambrian to Devonian were selected from the samples taken by the SEM devices of the University of Milan. The reason for choosing this species was the existence of 28 completely healthy oysters from this specimen, two of which had well-preserved articulate shells, and the evolution of age from young to old specimens can be observed in it. Microscopic studies on this species were performed by SEM devices of the University of Milan. A summary of these results and new achievements are presented in this article.
Original Research Paper
Stratigraphy and Palaeontology
zahraza khajehjavaran; gholamreza ghadami; Mohammad Poosti; Abbas moradian; behroz karimi
Abstract
Andesites are located in shahr-e-babak north, in central Iran, Urumieh- Dokhtar belt. The main texture in these rocks is porphyry and their phenocrysts are plagioclase (Andesine to Labradorite), pyroxene (Augite), amphibol (Tschermakite and Magnesiohornblende). These properties are signatures of calc- ...
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Andesites are located in shahr-e-babak north, in central Iran, Urumieh- Dokhtar belt. The main texture in these rocks is porphyry and their phenocrysts are plagioclase (Andesine to Labradorite), pyroxene (Augite), amphibol (Tschermakite and Magnesiohornblende). These properties are signatures of calc- alkaline series formed in a volcanic arc setting. Based on geochemical studies, the rocks show enrichment in LREE rather than HREE. The lack of significant Eu anomalies in REE pattern indicates oxidation state of magma during crystallization. Based on geochemical studies, the clinopyroxenes are Augite and have been crystallized from magma with almost 10% H2O. Fe3+ values of the clinopyroxenes reveal high oxygen fugacity in the magma. Based on the mineral chemistry data, pressure estimates from the clinopyroxenes in the range of 6-10 Kbr and composition yield the crystalization temperatures that range from 900-1100 OC. The typically clinopyroxenes occure at calc-alkaline orgenic igneous rocks. The plagioclase composition yield the crystalization temperatures that range from 650-750 OC. According to the present study, the rocks of the formed are probably the result of the subduction of the Neo-Tethys oceanic lithosphere below the Sanandaj-Sirjan zone, during the Eocene and in a volcanic arc environment.
Original Research Paper
Geophysics
Hamidreza Samadi; Roohollah Kimiaefar; alireza hajian
Abstract
One of the most important issues in seismology is to accurately determine the epicenter of earthquake, mainly because the accuracy of dependent studies such as seismic risk analysis, fault mechanism, depends on the accuracy of mentioned parameter. Double difference method is one of the conventional relative ...
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One of the most important issues in seismology is to accurately determine the epicenter of earthquake, mainly because the accuracy of dependent studies such as seismic risk analysis, fault mechanism, depends on the accuracy of mentioned parameter. Double difference method is one of the conventional relative earthquake relocation methods which is used vastly by seismological centers and it is used as the basis of an algorithm that relocates earthquake events about 0.004 second. In the proposed method, Adaptive Neuro-Fuzzy Inference System (ANFIS) is trained based on the former relocated events and generalized for new earthquakes. In the training procedure, the hypocentral information, for the main event and the nearest one (determined by K nearest neighbor search), and the velocity model of the region are considered as inputs and hypocentral information are set as target for the network. Here, with reference to the information of about 8000 earthquakes, as the training events, 490 earthquakes were relocated in about 0.1 (s) where RMS for predicating latitude and longitude of the events were 0.002 and for the depth parameter, RMS was 0.45. It is concluded that the proposed method could be considered as a powerful algorithm for near real time relocation of earthquakes.
Original Research Paper
Petrology
Farzaneh ValinasabZarnagh; Mohsen Moayyed; Ahmad Jahangiri; Hossein Azizi
Abstract
There are discontinuous outcrops of volcanic rocks in the West Azarbaijan province and in the north of Maku city. These volcanic complex were bimodal and compose of acidic and basic lava and pyroclastic rocks. Mineral chemistry studies show that clinopyroxenes in the studied rocks are diopside. These ...
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There are discontinuous outcrops of volcanic rocks in the West Azarbaijan province and in the north of Maku city. These volcanic complex were bimodal and compose of acidic and basic lava and pyroclastic rocks. Mineral chemistry studies show that clinopyroxenes in the studied rocks are diopside. These pyroxenes have a high magnesium number (0.87 to 0.99). Magma series and tectonic determination diagrams show that the basaltic rocks that make up the studied clinopyroxenes have an alkaline nature and were formed in a whitin plate environment. According to geothermobarometry studies, clinopyroxenes were formed at temperature 1100 - 1250 ° C and pressure of 3 - 9 Kbar. The depth for generation of magma was at about 22 kilometers.
Original Research Paper
Economic Geology
Fardin mousivand; Fatemeh Esmaeili; Mahmoud Sadeghian; Seyed Mehran Heidari
Abstract
Miandasht copper deposit is located in 24km north west of Abbasabad of Shahrood, and in the Cenozoic volcanic belt of north of Central Iran. Host sequence has Eocene age and include submarine flows (andesite and basalt), pyroclastic (tuff breccia and agglomerate) and sedimentary complex (Nomullitic limestone, ...
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Miandasht copper deposit is located in 24km north west of Abbasabad of Shahrood, and in the Cenozoic volcanic belt of north of Central Iran. Host sequence has Eocene age and include submarine flows (andesite and basalt), pyroclastic (tuff breccia and agglomerate) and sedimentary complex (Nomullitic limestone, sandstone and conglomerate). Mineralization occurred as stratabound and epigenetic, parallel to layering of the host rocks (tuff breccia and agglomerate) related to E6 unit, and along faults. The ores have vein- veinlets, open space filling, disseminated and replacement textures, and contain primary pyrite, chalcopyrite, chalcocite, bornit, and secondary chalcocite and malachite. Carbonatic- silicic, sericitic, argillic, and chloritic alterations are observed with mineralization. Tectonic setting of formation of the host sequence was a continental margin volcanic arc. Based on essential characteristics of copper mineralization at the Miandasht deposit such as tectonic setting, host rocks, mineralogy, and type of alterations, the Miandasht copper deposit shows many similarities with manto- type deposits, and formed during orogeny, folding and faulting of the host sequence. Development of argillic alteration and lack of extensive zeolitic alteration, distinguishes the deposit from other copper deposits in the Abbasabad region.
Original Research Paper
Petrology
Niloofar Nayebi; Dariush Esmaeily; Sourosh Modabberi; Ryuichi Shinjo; reza deevsalar; Bernd lehmann
Abstract
Sr-Nd-Pb isotopes and whole-rock geochemical analyses were carried out on plutonic rocks of the Chadormalu district to constrain the magmatic history of the Cadomian orogeny of the northern Gondwana margin during Late Precambrian–Early Paleozoic times. Despite the similarities in the geochemical ...
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Sr-Nd-Pb isotopes and whole-rock geochemical analyses were carried out on plutonic rocks of the Chadormalu district to constrain the magmatic history of the Cadomian orogeny of the northern Gondwana margin during Late Precambrian–Early Paleozoic times. Despite the similarities in the geochemical data, i.e., calc-alkaline affinity, enrichment in large ion lithophile elements (e.g., Rb, Ba, K, and Cs), and depletion in high field strength elements, e.g., Nb, Ta, P, Ti, and rare earth element patterns, however, bulk rock Sr-Nd isotope data rull out the co-magmatic nature of investigated basic (gabbro) and felsic (granite) magmas. Sr-Nd isotopic data (e.g., ɛNd(t)= -3.6 to +1.8) along with rather high (207Pb/206Pb)t attest to the crust-dominant, and mantle-derived melts for the granitoids and gabbros, respectively. The investigated zircons yielded the older ages for the gabbroic samples. The extensional tectonic regime followed by slab retreat or delamination brought flare-up of the oldest arc-related igneous rocks and interacted with Cadomian basement to form the investigated granitoid melts. The gabbroic rocks show geochemical and isotopic disruption and elevation of L-MREE/HREE ratios on the chondrite-normalized rare earth element (REE) patterns; interpreting the evidences of mantle heterogeneity and interaction with Paleoproterozoic basement.
Original Research Paper
Tectonics
Reza Alipoor; Ali Jahangiri; Zahra Ghasemi
Abstract
The Ghalajeh anticline with about 60 km length and NW-SE trend is located in Lurestan sub-zone and the Zagros fold and thrust belt. Geometry and kinematic of the folds of this zone are controlled by thrust faults and detachment levels. In this research, geometry and deformational style analysis of the ...
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The Ghalajeh anticline with about 60 km length and NW-SE trend is located in Lurestan sub-zone and the Zagros fold and thrust belt. Geometry and kinematic of the folds of this zone are controlled by thrust faults and detachment levels. In this research, geometry and deformational style analysis of the Ghalajeh anticline and the role of the detachment levels on folding style have been investigated interpreting well data and construction of three cross-sections and calculation of geometric parameters. The structure of this anticline is affected by two detachment levels, which include the Pabdeh and Garu formations as the upper and middle detachment levels. Detachment levels and deep-seated and surface thrust faults in the southwestern limb affected the folding geometry and have caused the high thickness of the middle detachment level and inversion of the southern limbwhich waning southwestern part of the anticline, and the dip of the layers are normal which in turn caused fracturing. Analysis of geometrical parameter along the Ghalajeh anticline indicate that this anticline is an asymmetrical, cylindrical fold is an open half-angle round fold.
Original Research Paper
Petrology
saeid samarbakhsh; mohamad hashem emami; Seyed mojtaba Mortazavi; mansor vosoghi abedini
Abstract
The study area, situated 50 km north of Ghaemshahr, structurally belongs to the Central Alborz tectonic zone. The volcanic rocks of the area, including basalt, andesite, trachyandesite, and dolerite are the products of fractional crystallization and some contamination processes. Clinopyroxene, olivine, ...
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The study area, situated 50 km north of Ghaemshahr, structurally belongs to the Central Alborz tectonic zone. The volcanic rocks of the area, including basalt, andesite, trachyandesite, and dolerite are the products of fractional crystallization and some contamination processes. Clinopyroxene, olivine, and plagioclase are the main minerals of these rocks. Porphyritic to mega-porphyritic texture with microlithic, glomeroporphyritic, and amygdaloidal matrix are observed in these rocks. Plagioclase, hornblende, and pyroxene can be considered the main mineral phases of these rocks. The rocks are enriched in LIL and LREE elements and depleted in HFS elements. The ratios of trace elements and rare earth elements in the studied region indicate that the basalts were formed by melting a garnet bearing peridotite at great depths and pressures. Negative Ce anomaly, Nb negative anomaly, Pb positive anomaly the role of continental lithosphere in contaminating the magmatic sources of volcanic rock in the study area. The Pb/Ce ratio similar to ocean island basalt (OIB) sources, induces OIB sources, the asthenospheric mantle, in the initial formation of basaltic magma. it can be concluded that the volcanic rocks of the area have formed in an intra-plate environment in an extensional regime.
Original Research Paper
Stratigraphy and Palaeontology
saeedeh senemari; Narges Monjezi
Abstract
Pabdeh Formation to Asmari Formation transition deposits were studied in the stratigraphic section of Khaviz located northeast of Behbehan. In the present research, the deposits of the upper part of Pabdeh Formation consisting shale and interbedded of argillaceous gray limestone with a thickness of about ...
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Pabdeh Formation to Asmari Formation transition deposits were studied in the stratigraphic section of Khaviz located northeast of Behbehan. In the present research, the deposits of the upper part of Pabdeh Formation consisting shale and interbedded of argillaceous gray limestone with a thickness of about 66 m were studied, which followed by deposits of the lower part of Asmari Formation with a thickness of about 21 m, including cream-colored clay limestone located. As a result of this study, 33 species belonging to 15 genera of calcareous nannofossils were identified. Based on the recorded bio-events and associated fossil assemblages, the bio-zones of Sphenolithus pseudoradians Zone, Ericsonia subdisticha Zone, Helicosphaera reticulata Zone, Sphenolithus predistentus Zone, Sphenolithus distentus Zone were determined. The studied zones are consistent with CNE20- CNO4/ CNO5 from Agnini et al. (2014) zonation. Based on the introduced bio-zones, the age of the upper part of Pabdeh Formation in the studied section of the Priabonin-early Rupelian and the age of the lower part of the Asmari Formation Rupelian -Chattian are suggested. In this study, the boundary between Pabdeh and Asmari formations is continuous, which indicates sedimentation with decreasing depth in the boundary of these two formations.
Original Research Paper
Geophysics
Reza Ghanati; Zahra Tafaghod Khabaz
Abstract
Inversion of VES data is formulated as a nonlinear problem and solved using multiple depth layers of fixed boundary and a few depth layers of the variable boundary. The model parameters in Smooth inversion are only the resistivity values. However, in the block inversion, the thickness of each layer is ...
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Inversion of VES data is formulated as a nonlinear problem and solved using multiple depth layers of fixed boundary and a few depth layers of the variable boundary. The model parameters in Smooth inversion are only the resistivity values. However, in the block inversion, the thickness of each layer is also added to the model parameters. Due to the non-linearity of the inverse problem, the determination of an appropriate initial model is very significant. A technique has been adopted to estimate a proper starting model for the block inversion strategy. Thus, from the solution of the smooth inversion, the second derivative of cumulative resistivity is calculated, then using the difference of turning points, the initial values of the model parameters are determined. The proposed algorithms are first tested on data derived from two artificial models and then implemented on two real data sets. The numerical experiments demonstrate that the smooth inversion of the geo-electrical sounding data due to less dependency on the initial model confronts fewer challenges proportional to the block inversion strategy. However, in the case of block inversion, an appropriate choice of the initial model makes it possible to determine the boundaries of the layers with more certainty.
Original Research Paper
Stratigraphy and Palaeontology
Nasrollah Abbassi; Mohammad Vahidinia; Saeid Tavana; Pooria Vaeznia
Abstract
Numerous vertebrate footprints have been found in the dislocated sandstone slabs in the Mashhad city, northeast Iran. Neogene sediments of the Chenaran township are supposed to be provenance of the studied slabs. Identified footprints includes artiodactyl tracks as ichnotaxa Bifidipes velox, Lamaichnum ...
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Numerous vertebrate footprints have been found in the dislocated sandstone slabs in the Mashhad city, northeast Iran. Neogene sediments of the Chenaran township are supposed to be provenance of the studied slabs. Identified footprints includes artiodactyl tracks as ichnotaxa Bifidipes velox, Lamaichnum guanicoe, Pecoripeda amalphaea, Pecoripeda isp., Carnivore tracks as Canipeda isp., and Felipeda isp., and bird tracks as Avidactyla isp., Avipeda gryponyx, Fuscinapeda texana. Among studied slabs, bird tracks are abundant. This is the first report of Cenozoic vertebrate tracks from the Kopeh Dagh geological zone. Discovery of Lamaichnum guanicoe shows Camelidae distribution in Iranian Plateau is as old as Neogene, and it is the first report of Camelidae sign from Iran. Presence of diverse footprints from Kopeh Dagh show attenable biodiversity in the region of Iran.
Original Research Paper
Petrology
Mohammad Fadaeian; Amin Allah Kamali; Kourosh Mohammadiha
Abstract
The study area is located in Ardabil province and northeast of Meshkinshahr city and structurally in Alborz-West-Azerbaijan zone. Tephritic dykes have pyroxenite and gabbro xenolites. Mineralogy of tephritic dykes and xenolites includes plagioclase, clinopyroxene, analcime, amphibole, olivine and phlogopite. ...
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The study area is located in Ardabil province and northeast of Meshkinshahr city and structurally in Alborz-West-Azerbaijan zone. Tephritic dykes have pyroxenite and gabbro xenolites. Mineralogy of tephritic dykes and xenolites includes plagioclase, clinopyroxene, analcime, amphibole, olivine and phlogopite. Porphyric, microcrystalline, granular and cumular microlytic textures are their main textures. According to the mineral chemistry data as well as the presence of shaped, homogeneous and coarse analcime crystals, it can be concluded that the analcime crystals are secondary and as a result of delayed magmatic reactions under hydrothermal conditions have been formed on the primary leucite crystals. The chemical composition of pyroxene mineral in tephritic dykes and gabbro xenolites is diopside. The studied clinopyroxenes with alkaline composition show good adaptation to the tectonic environment of the magmatic arc. Clinopyroxenes are also formed at low to medium pressures, indicating their crystallization during magma ascent and at different depths. The chemical composition of amphiboles related to pyroxenite xenolite is of the type of calcium amphiboles and magnesium stingite. The average geometry of the barometer based on the amount of aluminum for pyroxenite xenoliths is 7-9 kbar. Thermmetric studied indicated that the amphiboles formed is 900-950 ° C.
Original Research Paper
Stratigraphy and Palaeontology
Ahmad Lotfabad Arab
Abstract
In order to identify, classify and paleoecological study of Lower Cretaceous echinoid fauna in northwest of Kerman area, the stratigraphic section of Siriz, was selected and its specimen were sampled and studied. Echinoids were studied and identified from a rich and diverse collection of macrofossils ...
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In order to identify, classify and paleoecological study of Lower Cretaceous echinoid fauna in northwest of Kerman area, the stratigraphic section of Siriz, was selected and its specimen were sampled and studied. Echinoids were studied and identified from a rich and diverse collection of macrofossils (Echinoids, Brachiopods, bivalves, Gastropods and corals) and microfossils (foraminifera and ostracods), which present in this deposits. Sixteen genera and species of echinoids are reported for the first time from the region, among which six species are new and reported from Kerman area previously. The co-existence of echinoids and other fossil groups in Siriz area confirms an Aptian age for the sediments. Also, it can be concluded that a shallow, less than 50 meters and warm platform environment was prevailed during the deposition of the strata.
Original Research Paper
Stratigraphy and Palaeontology
Peiman Rajabi
Abstract
The Asmari Formation In the Lorestan area is clife forming and consist of medium to tick beded Limestone with Benthic Foraminifera. In this study, stratigraphic Sequence of Asmari carbonate formation in Chenareh Anticline section located in the south of Lorestan basin and Amiran Anticline section located ...
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The Asmari Formation In the Lorestan area is clife forming and consist of medium to tick beded Limestone with Benthic Foraminifera. In this study, stratigraphic Sequence of Asmari carbonate formation in Chenareh Anticline section located in the south of Lorestan basin and Amiran Anticline section located in the middle part of Lorestan basin were studied in terms of lithology and microbiostratigraphy. The thickness of Chenareh Section was 180 meters and the Section of Amiran Anticline was 158 meters. In total, more than 290 thin sections of both were prepared and examined in the laboratory. The results of the fossil studies based on the expansion of the Benthonic Foraminifer led to the introduction and presentation of 4 Assemblage Biozones in both stratigraphic sections. Of these, 3 Assemblage Biozones are related to Chenareh Anticline Stratigraphical section and 1 Assemblage Biozone is related to the Amiran Stratigraphical section. Asmari Formation is in the Chenareh section is oligo-miocene (chattian-Bordigalian) and in the Amiran section is miocene (Bordigalin). Asmari Formation in both sections of Chenareh and Amiran with Shabazan Formation is progressive-continuous and discontinuous, and in both sections of the upper boundary with Gachsaran Formation can be seen in the same way as evaporative sediments.
Original Research Paper
Geological Environment and Engineering
Farah Rahmani; Abdolreza Jafarian; razieh Lak; Javad Esmaeili
Abstract
The present study aims to determine the concentration of heavy metals and toxic metalloids in rice of Sari. Sampling was performed from 32 stations of the rice seed section. The soil-plant relationship was investigated in 6 stations using samples taken from rice soil and other plant parts such as roots, ...
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The present study aims to determine the concentration of heavy metals and toxic metalloids in rice of Sari. Sampling was performed from 32 stations of the rice seed section. The soil-plant relationship was investigated in 6 stations using samples taken from rice soil and other plant parts such as roots, stems, leaves, and bran. Soil and plant samples were prepared using ICP-OES and ICP-MS methods. The results showed that the mercury (Hg) concentration is usually about 0.07 ppm. However, it reaches about 0.09 ppm in some points (30% of the samples). The mean concentration of lead (Pb) is 0.91 ppm, which is close to its allowable limit. The study results attribute the origin of lead elements to the use of chemical zinc fertilizer in rice fields and paddy fields, as Pb concentration in areas with zinc (Zn) fertilizer consumption is about 3.99 ppm. The as concentration in Isa Khandagh is 1.15 ppm, suggesting a high deviation from the normal level. The concentration of trace elements in rice crops in different regions of Sari city compared with rice crops in some foreign cities shows a high correlation for chromium (Cr), cobalt (Co), As, magnesium (Mg), manganese (Mn), sodium (Na), and Zn.
Original Research Paper
Petrology
Ali Lotfi Bakhsh
Abstract
In the north of Ardabil (from Namin to Lahroud) there are widespread sequences of Eocene and Quaternary mafic to intermediate and felsic magmatic activities with different compositions. The composition of these rocks varies from basaltic lavas as well as dacitic and rhyolitic domes in Namin to basalt ...
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In the north of Ardabil (from Namin to Lahroud) there are widespread sequences of Eocene and Quaternary mafic to intermediate and felsic magmatic activities with different compositions. The composition of these rocks varies from basaltic lavas as well as dacitic and rhyolitic domes in Namin to basalt and basaltic andesite in Lahroud area. The chemical composition of olivine from olivine basaltic lavas indicates a forsterite composition changing from 67.8 to 92.7. Clinopyroxenes show diopside composition whereas plagioclase has labradorite to bytownite composition. Garnet xenocrysts in the rhyolitic domes have an almandine composition. These rocks are characterized by the enrichment in LREEs compared to the HREEs. Mafic-intermediate rocks show shoshonitic to high-K calc-alkaline composition whereas dacitic and rhyolitic domes show adakitic signature. Geochemical and isotopic characteristics of basaltic-andesitic rocks indicate their genesis are related to the partial melting of a metasomatized mantle wedge, re-fertilized by sediments and fluids from the subducting slab in the Eocene subduction zone of Iran. The geochemical and isotopic signatures of dacitic-rhyolitic domes indicate their origin from partial melting of the lower parts of the thickened continental crust of Iran.
Original Research Paper
Petroleum geology
Shadi Mohavvel; Golnaz Jozanikohan; Sohaila Aslani
Abstract
The presence of clay minerals of any type, amount or distribution pattern in hydrocarbon wells causes numerous problems in the formation evaluation. In this research, 15 core samples from Asmari Formation in the Maroun Oilfield were selected in order to study the type and distribution pattern of clay ...
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The presence of clay minerals of any type, amount or distribution pattern in hydrocarbon wells causes numerous problems in the formation evaluation. In this research, 15 core samples from Asmari Formation in the Maroun Oilfield were selected in order to study the type and distribution pattern of clay minerals by laboratory investigations. The XRD and microscopic results showed the studied samples consisted mainly of quartz (14.7-72.2%) and carbonate minerals (3.0-65.4%) as main constituent phases; while the plagioclase (0.0-6.7%) and clay minerals (3.3–44.5%) were identified as the main accessory minerals. In some samples, sulfide and ferrous minerals (0.0-2%) were also identified. The calculated percentage of illite in mixed-layer smectite/illite showed the diagenesis has occurred at different depths of reservoir. The SEM/EDX analysis performed on various types of clay minerals showed that kaolinite size varied from 0.7 to 6.5 μm in studied samples. In addition, Illite size ranged in our studied samples from 0.4 to 3.6 μm. Our results indicate that the clays in the Asmari Formation occur in three main patterns as dispersed, pore-bridging and pore-filling with the variation of the total amount of clay minerals, min 3.3% and max 44.5% across the length of Asmari Formation.
Original Research Paper
Stratigraphy and Palaeontology
Fatemeh Vaez-Javadi; Abbaszadeh Mahdi
Abstract
Plant macrofossils of Hojedk Formation were studied in a well of the Mazino region, southwest of Tabas, so that 29 species of plant macrofossils belonging to 15 genera of various orders were identified. One local interval biozone- Ptilophyllum harrisianum-Klukia exilis Interval zone were recognized. ...
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Plant macrofossils of Hojedk Formation were studied in a well of the Mazino region, southwest of Tabas, so that 29 species of plant macrofossils belonging to 15 genera of various orders were identified. One local interval biozone- Ptilophyllum harrisianum-Klukia exilis Interval zone were recognized. Based on the occurrences of the Equisetites sp. cf. E. beanii, Klukia exilis, Ptilophyllum harrisianum, Nilssonia macrophylla, and Elatides thomasii, an early Middle Jurassic (Aalenian-Bajocian) age is considered for this plant macrofossil assemblage. The relative abundance of Filicales (ferns), Cycadales, Pinales, and Equisetales are 43.18, 31.82, 13.63, and 4.64, respectively. Moreover, the results of similarity indices of plant macrofossils indicate relatively strong value of similarity between the plant macrofossil assemblage of the Mazino area and elsewhere in Tabas Block. Besides, floral gradient score of this assemblage is 54.89. Based on the paleontological and lithological evidences, a humid ‘warm temperate biome’ is considered for this locality. Moreover, it is confirmed that a uniform vegetation and palaeoclimate occurred in Tabas Block during the Middle Jurassic and that Iran was located within Vakhrameev’s Euro-Sinian region, Transcaspian subprovince.
Original Research Paper
Petrology
Jalil Ghalamghash; Meysam Akbari; Reza Jamal
Abstract
The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate inclusions ...
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The Taftan volcano hosts an extensive volcanic activity during Late Miocene to Quaternary where took place over Makran zone. Taftan rocks are mainly basaltic andesite, andesite, trachyandesite, and dacite that occur as lavas and pyroclastic rocks. They are characterized by basic-intermediate inclusions enclosed by acidic groundmass, and disequilibrium textures in plagioclase phenocrysts including sieve texture, zoning, and dissolution margin, which may reflect magma mixing. These rocks record high-K calc-alkaline to calc-alkaline affinity with enrichment in LREE and LILE relative to HREE and HFSE, respectively. These features, coupled with the clear depletion in HFSE (such as Nb, Ta, and Ti) are consistent with typical subduction-related volcanic arcs. Taftan primary melts might have been produced by ~15% partial melting of spinel lherzolite mantle. The normalized multi-element patterns which mimic the upper continental crust values, and enrichment in Pb, Th, U, and Rb agree well with magma evolution by assimilation and fractional crystallization (AFC). The available isotopic geochronology dataset reveal that the youngest volcanoes of the Makran-Chagai magmatic arc are Bazman and Kuh-e-Sultan volcanoes. A geochemical comparison of these volcanoes highlights that magmatism in the Taftan where the crust is thick, underwent a higher degree of crustal assimilation en route to the surface.
