F. Rostami; V. Ahmadi
Abstract
In this research two stratigraphic sections of Lower Cretaceouse to Upper Jurassic sedimentary (Surmeh and Fahliyan Formation in Folded-Zagros Zone) have been selected. Based on microfacies studies (in 400 thin-sections) three species of Ichnofossils microcoprolites from Crustaceans related as the Follow: ...
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In this research two stratigraphic sections of Lower Cretaceouse to Upper Jurassic sedimentary (Surmeh and Fahliyan Formation in Folded-Zagros Zone) have been selected. Based on microfacies studies (in 400 thin-sections) three species of Ichnofossils microcoprolites from Crustaceans related as the Follow: Palaxius decaochetarius, Helicerina siciliana, Palaxius tetraochetarius, palaxius isp. In general, considering Ichnotaxons studies, two assemblage-zones were identified for microcoprolites Crustaceans. Assemblage-zone (No:1) of Tithonian to Berriasian and assemblage-zone (No:2) whichis lated of Valanginian, taxons Helicerina isp. Assemblage-zone (No:2) which is related.
K. Seyed Emami; N. Behfar; M. R. Majidifard; A. Behfar
Abstract
Middle Jurassic strata are well developed northeast of Damghan (E Alborz). At the study section the Dalichai Formation has a maximum thickness of 156 m, consisting of an alternation of bluish-grey limestones and marls, being subdivided into 4 members. The lower boundary with the siliciclastics of the ...
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Middle Jurassic strata are well developed northeast of Damghan (E Alborz). At the study section the Dalichai Formation has a maximum thickness of 156 m, consisting of an alternation of bluish-grey limestones and marls, being subdivided into 4 members. The lower boundary with the siliciclastics of the underlying Shemshak Formation is unconformity, due to the Mid-Cimmerian tectonic event, whereas the upper boundary with the light and cliff-forming carbonates of the Lar Formation is gradational. The Dalichai Formation at the study section is very fossiliferous. Summing up 1750 fossil specimens were collected, among which the ammonoids with 1491 specimens clearly predominate. Altogether 27 genera, 33 species of ammonites, belonging to 6 biozones (Parkinsoni Zone, Zigzag-Aurigerus zones, Subcontractus Zone, Bullatus-Gracilis zones, Anceps-Coronatum zones, Athleta Zone) has been recognized. In addition 17 genera and 8 species of planktonic and benthic foraminifers are described.These can be divided into 2 biozones. The fossil-content is mainly concentrated within few meters of red and nodular limestone in the upper part of the section. Based on the ammonite fauna the age of the Dalichai Formation in the investigated area ranges from Upper Bajocian to Oxfordian. Paleobigeographically the fauna shows close relationship to western Europe and Sub-Mediterranean region. This indicates a paleogeographic position of the area at the northern Tethys during the Middle-Upper Jurassic.
R. Shabanian
Abstract
The Permian sequences of Aru and Bibishahrbanoo sections comprise the Dorud, Ruteh and Nesen formations respectively. A precise dating of the formations was provided based on the analysis of smaller foraminifers and fusulinid assemblages. The clastic Dorud Formation refered to Asselian and Sakmarian ...
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The Permian sequences of Aru and Bibishahrbanoo sections comprise the Dorud, Ruteh and Nesen formations respectively. A precise dating of the formations was provided based on the analysis of smaller foraminifers and fusulinid assemblages. The clastic Dorud Formation refered to Asselian and Sakmarian stages. The platform limestone of Ruteh Formation corresponds to Kubergandian – Murgabian stages. The Laterite and Bauxite horizon in the studied area attributed to Midian and finally, the uppermost beds of Permian in Bibisharbanoo corresponds to Early Dzhzulfian, based on the proposed of international subcommission on Permian stratigraphy concerning Tethyian stage bourdaries. Biolithic limestones of Ruteh Formation lying transgressively and disconformably on the underlying clastic and continental Dorud Formation with a great hiatus consists of Yachtashian and Bolorian stages. In both stratigraphical sections, thin vermiculate and oolithic limestone of Elika formation belonge to Early to Middle Triassic lying disconformably on the Permian sequence with hiatus. The hiatus between Permian and Triassic in Aru comprise Dzhulfian and Dorashamian stages and in Bibi Shahrbanoo stratigraphical section include Late Dzhulfian and Dorashamian stages. In this study 45 species belonging to 40 genus related to fusulinid families, smaller foraminifers and calcareous algae were recognized.
Mohammad Tatar; M. Tatar; A. Kaviani
Abstract
Crustal structure of the Iranian plateau which is located between two convergent Arabian and Eurasian plates is studied. Teleseismic earthquakes recorded by broad band stations of Iranian National Seismic Network (INSN) are used to compute the receiver functions for each station. Rayleigh wave ...
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Crustal structure of the Iranian plateau which is located between two convergent Arabian and Eurasian plates is studied. Teleseismic earthquakes recorded by broad band stations of Iranian National Seismic Network (INSN) are used to compute the receiver functions for each station. Rayleigh wave phase velocity dispersion curves were estimated employing two-station methods for all possible station pair of the above mentioned seismic network. A combined inversion of Rayleigh wave phase velocities and body wave receiver functions increases the uniqueness of the solution over separate inversions and also facilitates explicit parameterization of layer thickness in the model space. Our result indicates the crustal thickness differs from a minimum of 40 ±2 km in southeast of Iran, (ZHSF) to a maximum of 56 ±2km beneath the Sanandaj-Sirjan zone (SNGE). We observe a crustal thickness of 47 ±2km beneath the central Zagros (GHIR) to 52 ±2km below the eastern most of Zagros (BNDS), then to 47 ±2km beneath the northwestern part of the Zagros (SHGR). Crust of the Central Iran (KRBR) has a thickness of 48 ±2 km while the average Moho depth in southern parts of the Central Alborz (DAMV and THKV stations) is 54±2km. Our analysis shows a thinning of the crust to 43 ±2 km beneath the northwest of Iran (MAKO) and western part of the Caspian basin (GRMI).
K. Bazargani-Guilani; M. Parchekani
Abstract
Barik-Ab Pb-Zn (Cu) ore deposit located in 2 km for front Barik-Ab village in north of Abhar town, south eastern of Zanjan province. According to the geological classification of Iran , this area located in Taroum mountains and is a part of west Alborz range , Alborz-Azarbaidjan zone or west of central ...
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Barik-Ab Pb-Zn (Cu) ore deposit located in 2 km for front Barik-Ab village in north of Abhar town, south eastern of Zanjan province. According to the geological classification of Iran , this area located in Taroum mountains and is a part of west Alborz range , Alborz-Azarbaidjan zone or west of central Alborz with the trend of NW – SE, located in Upper Cretaceous magmatic belt. In the Taroum Mountains, the main outcrops are volcanic and pyroclastic rocks which this sequence is comparable with Karaj Formation and divided into two members. The lower member is called Kordkand (2400 m) and the Upper member named Amand (1400 m).Amand member is divided to 6 submembers. Submembers are Ea1, Ea2, Ea3, Ea4, Ea5, and Ea6. Outcrops in the studied Area are Ea4, Ea5 and Ea6. Barik-Ab ore deposit occurred in Ea4 which is included andesite, rhyolite, breccia tuff, tuff and sandstone and tuffacouse mudstone rocks. Host rocks are rhyolitic, dacitic and rhyodacitic tuffs. Mineralization in Barik-Ab Pb-Zn(Cu( ore deposit divided in two stages: in the first stage mineralized hypogen ore minerals including sphalerite, galena, chalcopyrite, pyrite, bornite and, in second stage formed covelite , malachite , azurite hematite, goethite and limonite by enrichment processes. According to the increase of Cd and decrease of Zn/Cd in the sphalerite and galena and up value of Ag and Sb and decrease of Se/S*10-4 in the galena and the correlate with other Pb-Zn mineralization types, Barik-Ab Pb-Zn(Cu) ore deposit formed by influence of medium temperature? Hydrothermal fluids into tuff host rocks after the Eocene and mineralization occurred with veinlets and vein formed in the joints, fracture and faults with Silicification alteration in host rock.
A. Kamali; M. Moayyed; M. Jahanbakhsh Ganjeh; H. Pirooj; M. Jokar; A. Ameri
Abstract
The studied area is located at southeast of Myaneh, in east Azarbaijan province. The tourism industry, especially geotourism is a new approach for improving of coexistence of human and nature, in order to make economic benfites is nowadays very important for local development. By evaluation of natural ...
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The studied area is located at southeast of Myaneh, in east Azarbaijan province. The tourism industry, especially geotourism is a new approach for improving of coexistence of human and nature, in order to make economic benfites is nowadays very important for local development. By evaluation of natural potential of areas with direction, planning and physical developments in the direction of tourisms industry and absorption of tourist especially in national and international scale, can help to provide job opportunities.This study, by investigating a small sample of geotourism potential of the country, tries to help a new approach towards the natural resources of the country. Threfore in this study, for investigation and evaluation of geotourism potentials of the study area, the taget function and traversing the geomorphological and geological features are carried out. In the model, using advantage coefficient (dij), it is possible to allocate tourism potential preferential to different locations and announce the location with highest advantage coefficient as top tourism localities. This research is a case study for using advantage coefficient model for the Qaflankuh area in east Azarbaijan. This area has unique, intact historical and natural features that can attract tourists. The variety of rocks in the area (andesite, basalt, rhyolite, ignimberite, fissure dykes, agates, perlite, faults, agglomerates, volcanic breccias, and volcanic bomb) has provided spectacular sights for every geosciences and geography. Qaleh Dokhtar and Pol- Dokhtar are example of historical-cultural sites. The results of this study, introduces the study area as a scientific geopark and as a natural history museum.
K. Nezhadafzali; R. Lak; M. Sarvati; F. Bayatani
Abstract
Mud volcanoes are natural and site-seeing phenomena in the world, particularly in the Alps and Himalayas belts. Mud volcanoes usually appear in form of a dome or a pool. The mud volcanoes comprise water, gas and mud. with plenty of applications, like tourism, mud therapy, supplying of essential ...
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Mud volcanoes are natural and site-seeing phenomena in the world, particularly in the Alps and Himalayas belts. Mud volcanoes usually appear in form of a dome or a pool. The mud volcanoes comprise water, gas and mud. with plenty of applications, like tourism, mud therapy, supplying of essential body trace elements, and their usage as mud for pottery. In Iran most of the mud volcanoes appear in coastal plains of the Caspian and Oman Seas. A mud flow was formerly found between Minab and Jask in Hormozgan Province. These types of exclusive, beautiful and natural phenomena require more attention by tourism industry. On the other hand, mud flow must be introduced as the most important geotourism phenomenon of northern coast of the Oman Sea. In this research, after data collection, including topography and geology maps, AIRS satellite data and aerial photos, remote sensing verifications were implemented. Then, mud flow determination was completed by field work studies and checking. A sediment sample was taken from each mud flow in the field work, then analyses of major, accessory and trace elements were carried out by using ICP-OES. About 30 small and big mud volcanoes around of Gavak mountain and 6 mud volcanoes at Gatan and Tojak area were determined in Hormozgan province that they have not been introduced before. The biggest mud volcanoe (Aryana) has cone with 73m hight at Gatan area and the smallest one has cone with less than 1m at Gavak area. Meantime, hydrogeochemical studies or determination of the percentage of available elements for all mud volcanoes were implemented. Since this geomorphological phenomenon indicates tectonic activity of a region, hence there is a possibility of mild earthquake and faulting occurrence. This issue must be considered in construction of buildings and certain fixed structures, such as bridges. Emitted gases through mud volcanoes relatively indicate the internal conditions of the Earth, particularly existence of oil and gas reservoirs. Mud flow is an index for availability of oil and gas reservoirs. They are used for prediction of availability of these reservoirs inside the Earth.
M. Khosroshahi; F. Mahmoudi; M. T. Kashki
Abstract
In this article, we try to study deserts of Iran on the basis of geological specifications with the help of 1:100000, 1:250000 scaled maps of G.S.I and N.I.O.C using Geographical Information System (GIS) methodology. Then quaternary and evaporate formations in every study province were recognized. Saline ...
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In this article, we try to study deserts of Iran on the basis of geological specifications with the help of 1:100000, 1:250000 scaled maps of G.S.I and N.I.O.C using Geographical Information System (GIS) methodology. Then quaternary and evaporate formations in every study province were recognized. Saline and evaporatic formations were determined as “primary deserts”. With overlaying drainage network on the basic map of Quaternary formations, the secondary deserts were recognized. Both of these processes (The primary and secondary deserts) have formed provincial deserts. After recognition of the provincial deserts in the country map by utilization of the coordinate system of Iran's map georeferences and control check point all desert units were set up on the whole country map. Results showed that 12.6% (208041 km2) of Iran is known as deserts formed by evaporate formations.
M. Mohamadian; M. Boomeri; A. Ahmadi; A. A. Moridi Farimani; H. Daglas; M. Jamali
Abstract
Sungun Porphyry Copper Deposit is located about 130 km to the northeast of Tabriz, northeast Iran. This deposit contains 796 million tons of ore with 0.61% Cu, 0.01% Mo, 0.016 ppm Au, 9.75 ppm Bi and Re (0.09 wt% of molybdenite). This research studies the physico-chemical environment using the chemical ...
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Sungun Porphyry Copper Deposit is located about 130 km to the northeast of Tabriz, northeast Iran. This deposit contains 796 million tons of ore with 0.61% Cu, 0.01% Mo, 0.016 ppm Au, 9.75 ppm Bi and Re (0.09 wt% of molybdenite). This research studies the physico-chemical environment using the chemical properties of minerals of this deposit. This deposit is related to granodiorite-diorite dikes and granodiorite stock that intruded into sedimentary and volcanic rocks of Cretaceous and Eocene. Dominant alterations are potassic, phyllic, argillic and propylitic from center outward which are characteristics of continental margin porphyry copper deposits. Simultaneously with the supergene mineralization, an iron cap of iron oxides, iron hydroxides, copper oxides, sulfates, carbonates and copper phosphates were developed on top of the deposit and along the fractures. In conclusion, based on mineral chemistry, in 450 ºC and 0.5 kb pressure (PT condition of potassic zone), sulfur fugacity and pH is determined to be as: log¦S2=-18 to -24 an pH=2.5 to 7.5. In 350 ºC and 0.5 kb pressure (PT condition of phyllic zone), oxygen and sulfur fugacities are: logƒO2= -20 to -33 and log¦S2=-6 to -15.
S. H. Hejazi; M. H. Adabi; S. R. Moussavi Harami
Abstract
The Givetian-Frasnian sandstones in the Kuh-e-Tizi section (25 km NE Kerman), unconformably overlie the Upper Cambrian Kuhbanan and underlie the Lower Carboniferous Hutk Formations respectively, in southeastern Central Iran. Petrographical data show that these sandstones are well-sorted, sub-angular ...
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The Givetian-Frasnian sandstones in the Kuh-e-Tizi section (25 km NE Kerman), unconformably overlie the Upper Cambrian Kuhbanan and underlie the Lower Carboniferous Hutk Formations respectively, in southeastern Central Iran. Petrographical data show that these sandstones are well-sorted, sub-angular to rounded quartzarenite. Diagenetic features include physical and chemical compactions (straight, concavo-convex, sutured grain contacts and pressure solution of quartz grain), reduction of the pore space through rearrangements and cementation (mostly silica, as quartz overgrowth). The provenance and tectonic setting of these sandstones have been interpreted using integrated petrographic and geochemical data. Petrographic analysis using standard methods revealed that mono and poly-crystalline quartz grains have been derived from plutonic rocks of an interior cratonic setting. Trace element analyses and their ratios used for provenance studies (Th/Sc and La/Sc) are similar to sediments derived from weathering of mostly felsic rocks. Values representing chemical index of alteration (CIA) and the plagioclase index of alteration (PIA) range from 44.24 to 83.43, with an average of 69.96, and from 42.98 to 92.56, with an average of 75.8, respectively. However, most samples have values greater than 60, suggesting moderate to high weathering in the source area or during transportation prior to find deposition. Major and trace element concentrations indicated a depositional setting in a passive continental margin.
Ahmad Zamani; S. Farahi Ghasre Aboonasr
Abstract
The Iranian plateau is one of the active tectonic regions on the earth. Non-uniformly distribution of deformation and repetitive activity of faults have cause a complex pattern of tectonic and seismotectonic activity of Iran. Therefore, in order to study the seismic and geological behaviors of different ...
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The Iranian plateau is one of the active tectonic regions on the earth. Non-uniformly distribution of deformation and repetitive activity of faults have cause a complex pattern of tectonic and seismotectonic activity of Iran. Therefore, in order to study the seismic and geological behaviors of different parts of the country one has to perform tectonic and seismotectonic zoning. Tectonic and seismotectonic zoning of Iran began by conventional methods in the past and developed by numerical zoning in recent years. Conventional methods aren't capable for producing detailed zoning maps. Recently numerical data and statistical and mathematical models have used for produce modern numerical maps. The advantage of numerical pattern recognition is that this method is a powerful tool for objective interpretation of massive of data. Multivariate statistical methods not only apply for tectonic zoning, but also this is useful to reveal the degree of significance and relationship between effective variables on tectonic zoning. In this paper, a large numbers of up-to-date geophysical, seismological, geological and geomorphological data have analyzed by using multivariate statistical methods to produced self-organized numerical tectonic and seismotectonic zoning of Iran. Based on this techniques a seven zoning tectonic and seismotectonic map has constructed for Iran. The role and significance of various parameters have also investigated using ANOVA method. The results indicate that some of the parameters play more important role in self-organized zoning. Based on relationships between parameters, they are been classified into 12 groups. Variables in each group present maximum correlation with each other. It is interesting to note that despite the frequent application of a- and b- values of the Gutenberg Richter magnitude frequency formula, these values show poor correlation with others and do not play a significant role in zoning.
A. Arzani; S.A. Alavi; M. Pooladzadeh; A.R. Golalzadeh; Z. Mehdipoor
Abstract
The area that will be discussed in this study is located between Zagros and Arabian structural zones in Iran in which full fold 3D seismic data has been acquired and interpreted using sophisticated techniques. This paper covers the role of structural sensitive seismic attributes including first and Second ...
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The area that will be discussed in this study is located between Zagros and Arabian structural zones in Iran in which full fold 3D seismic data has been acquired and interpreted using sophisticated techniques. This paper covers the role of structural sensitive seismic attributes including first and Second Derivative attributes, Azimuth attribute, Variance Cube attribute and Seismic Inversion attributes as an advanced stage of the interpretation program in delineating and resolving structural ambiguities in the mentioned field. The result of this study using integrating these attributes shows the interference structural features such as superimposed folding and structural basin in NW nose of the field of study. Hence it seems that an interference folding event to be most probably occurred between Zagros and Arabian structures and made a very gentle refolding belt. Complementary geophysical studies also show a reservoir of good potential in some parts of this belt that located in this field of study.
M. Talebian; S. H. Tabatabaei; M. Fattahi; M. Ghorashi; A. Beitollahi; A. Ghalandarzadeh; M.A. Riahi
Abstract
The Iranian plateau lies between the Arabian and Eurasian plates and accommodates approximately 22 mm/yr of N-S shortening. About 9 mm/y of this shortening is taken up by folding and thrusting in the Zagros while the remaining 13 mm/yr is taken up in the Alborz and Kopeh-Dagh. The Central Iran ...
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The Iranian plateau lies between the Arabian and Eurasian plates and accommodates approximately 22 mm/yr of N-S shortening. About 9 mm/y of this shortening is taken up by folding and thrusting in the Zagros while the remaining 13 mm/yr is taken up in the Alborz and Kopeh-Dagh. The Central Iran block is relatively stable and thus moves to the north with an average velocity of about 13 mm/y. As the stable Afghanistan block lies to the east, the northward motion of Central Iran produces a right-lateral shear in eastern Iran, which is distributed mainly over a few major faults to the west (~5 mm/yr) and east (~ 8 mm/yr) of the Lut desert. Limited information is available about the slip rates of individual faults in eastern Iran; therefore in this study we try to combine all geological, geodetic and available Quaternary dating results to estimate the fault slip rates and distribution of active deformation in eastern Iran. Finally, we report the results from OSL dating of samples taken from uplifted plain deposits near the south end of the Bam-Baravat fault. These results show that this fault is growing in the vertical direction with at a rate of ~ 0.5 mmy-1. Considering geometric relation between the Bam-Baravat and the south Bam earthquake fault, we estimate a slip rate of about 2 mm/y for the south Bam earthquake fault.
S. Khederzadeh; A. Bahrodi
Abstract
Sand box models are in order to investigation of circumstance of deformation create in orogenic event. Progressive rigid indenter is as non-plastic continental crust that moves from one side to ward sand hanging wall that is indication plastic crust. The sand primery thickness and angle of rigid indenter ...
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Sand box models are in order to investigation of circumstance of deformation create in orogenic event. Progressive rigid indenter is as non-plastic continental crust that moves from one side to ward sand hanging wall that is indication plastic crust. The sand primery thickness and angle of rigid indenter are changeable. In the all of models, rises sand in the two side of plan of indenter between fore-slop and back-slop, in the top of indenter progressive edge. The formation rate of anticlinorium folds is related to thickness of sand hanging wall, form of progressive and rate of falling's back-slop plan. Change of primery thickness of sand hanging wall is controler of distance and rate of anticlinorium folds formation. The aim of this experimental work is investigation of thrust belts, progressive indenter, and research of effect's slope in the collision zones and fold-thrusts creation, also comparison of experimental model to natural model.
I. Maghfouri Moghaddam
Abstract
Rudists of the Tarbur Formation, in 7 km southwest of Semirum and 10 km north of Khorramabad, have been studied. Paleontological studies indicate that the age of the Tarbur Formation in both sections is Masstrichtian, and has a rich macrofossil fauna of rudist. The important types of rudist include Radiolites, ...
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Rudists of the Tarbur Formation, in 7 km southwest of Semirum and 10 km north of Khorramabad, have been studied. Paleontological studies indicate that the age of the Tarbur Formation in both sections is Masstrichtian, and has a rich macrofossil fauna of rudist. The important types of rudist include Radiolites, Hippurites and Caprinidae. The assemblage shows a close similarity with those reported from south Turkey, Mediterranean, Saudi Arabia and Oman.
zahra badrzadeh; M. Sabzehei; E. Rastad; M. H. Emami; D. Gimeno
Abstract
The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons ...
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The Sargaz massive sulfide deposit is situated near Jiroft (south-east Kerman), in the southern Sanandaj-Sirjan Zone. The host rocks are Upper Triassic to lower Jurassic(?) pillow basalt. The occurrence of mineralization in basaltic to basaltic andesite, the existence of Jaspilite and Fe-Mn horizons in distal part of the deposit, the occurrence of a stringer zone discordantly under massive ore, the presence of pyrite as the main sulfide mineral, brecciated textures and mineralogical zonation in the massive ore, all suggest that the Sargaz deposit can be classified as a volanogenic massive sulfide deposit. The mineralogy is reasonably simple, with pyrite being the main sulfide mineral, with lesser chalcopyrite and sphalerite. On the basis of different generation of minerals, shape, size, their mutual geometry, relative timing of crosscutting structures and replacement features, brecciated textures and mineralogical zonation indicate that the growth history of the Sargaz deposit was complex due to syn and post depositional processes. Based on mineralogical, textural and paragenetic relationships, four principal stages of mineralization are recognized. Stage I mainly consist of fine grained pyrite (As rich), and locally sphalerite, quartz and barite. Framboidal pyrite, colloform pyrite and sphalerite were formed during this stage. After stage 1 mineralization, collapse of the sulfide mounds took place probably due to dissolution of anhydrite matrix, producing accumulations of pyrite breccias. Following this mound collapse, during stage II, pyrite (Co rich), sphalerite, tetrahedrite-tenantite and galena were formed as euhedral and coarse grains. Stage III deposits consist of chalcopyrite replacements and zone refining process. During this stage, due to zone refining, a chalcopyrite-pyrite zone was developed at the lower part of the massive sulfide lens and a sphalerite-rich zone formed in the upper part. During stage IV, over refining process, led to the dissolution of stage III chalcopyrite and base-metal depleted pyrite body in the lowermost part of the massive sulfide lens and carbonate veins were emplaced into the sulfide lens replacing earlier barite.
R. Shabanian; M. Parvanehne-Nezhad Shirazi; F. Javadinia
Abstract
The detailed stratigraphical and lithological analysis of the Permian sequence in north Marand, NW of Iran at Harzand village has been studied . At this locating the Permian sequence consist of Dorud (82 m..) Surmaq (258 m..) and Julfa (108 m.) formations respectively. The main lithology consist ...
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The detailed stratigraphical and lithological analysis of the Permian sequence in north Marand, NW of Iran at Harzand village has been studied . At this locating the Permian sequence consist of Dorud (82 m..) Surmaq (258 m..) and Julfa (108 m.) formations respectively. The main lithology consist of white to red sandstone, grey to dark, biogenetic limestone , marly limestone and thin bedded limestone. The lower boundary is non conformity, so that the Permian sequence is underlying a thick extrusive igneous rocks and at the top, a sequence of Miocene red clastic deposit covers the Permian sequence with disconformably. In this study 52 foraminiferal species belonging to 37 genus and 8 species of 9 Algal genus were recognized and 4 assemblages biozones in Surmaq and Julfa formations have identified. Based on fossils assemblages , the age of the Surmaq formations is Kubergandian - Murgabian (Middle Permian) and the age of Julfa formation is Middian - Early Dzhufian Stages(Late middle –Early late Permian).
M. Ghasemi; M. Momenzadeh; A. Yaghubpur; A. A. Mirshokraei
Abstract
Mehdiabad Zn-Pb-Ba deposit is located 110 km south-east of Yazd, in the Central Iran structural zone. The stratigraphic succession consists of three sedimentary formations of lower Creataceous age. The Sangestan formation, the lowest unit of shale and siltstone with calcarenitic interbeded layers. This ...
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Mehdiabad Zn-Pb-Ba deposit is located 110 km south-east of Yazd, in the Central Iran structural zone. The stratigraphic succession consists of three sedimentary formations of lower Creataceous age. The Sangestan formation, the lowest unit of shale and siltstone with calcarenitic interbeded layers. This unit is overlain by ankeritic massive dolomite and dolomitic limestone of Taft formation. The Abkouh formation at the top is composed of cherty or clayey limestone with conglomeritic intercalation, lenses of massive reef limestone and calcareous shale. The structure of ore body shows a half-graben with a vast N-S syn form being complicated by the presence of poly phase faults. The main normal fault is Tappeh Siah fault, suggested to be active during and after the period of sedimentation. Major minerals are sphalerite and galena with minor pyrite, chalchopyrite in sulfide zone, smithzonite, hydrozincite, hemimorphite and cerussite in oxide zone. Mineralization occurs in stratiform-lenticular orebodies and concordant with host rocks. Also ore bodies showing laminated, disseminated, open space filling, karst filling, colloform and botryoidal textures.
H. R. Nankali; B. Vosoughi; F. Soboutie; K. Hessami; M. Talebian
Abstract
A three-dimensional lithosphere model with horizontal dimensions of 1500 km×600 km and a depth extent of 70 km for the Zagros is constructed from available geophysical data to find out strength of the outermost layers in this area. The structural boundaries of the model are based on the results ...
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A three-dimensional lithosphere model with horizontal dimensions of 1500 km×600 km and a depth extent of 70 km for the Zagros is constructed from available geophysical data to find out strength of the outermost layers in this area. The structural boundaries of the model are based on the results from the deep seismic sounding profiles. First the finite element model for the temperature is solved in order to obtain initial temperature and the geotherm, after that structural viscoelastic problem is solved using the same mesh as in the thermal initial condition. Preliminary results for wet and dry rheology indicate that the depth of the BDT is about 8 km and 11 km for hot geotherm and 10.5 km to14 km for cold geotherm. The results are in good agreement with focal depth in the Zagros that most earthquakes occur in 8 to 15 km depth (Tatar et al., 2004 and Jackson et al., 2008), that the long-term strength of the continental lithosphere resided only in its upper part, which was contained wholly within the crust.
N. Hashemi
Abstract
This paper presents a study of the spatial variation of Gutenberg-Richter seismic b-value over the Iranian region. For this purpose, based on the works carried out by investigators for tectonic and seismotectonic zoning of Iran, the region subdivided into five structural zones, namely, Alborz-Kopet Dagh ...
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This paper presents a study of the spatial variation of Gutenberg-Richter seismic b-value over the Iranian region. For this purpose, based on the works carried out by investigators for tectonic and seismotectonic zoning of Iran, the region subdivided into five structural zones, namely, Alborz-Kopet Dagh zone, Azarbaijan zone, East-Central Iran zone, Makran zone, and Zagros zone. Then, the seismic b-value parameter has been computed for these five zones. The results obtained reveal that among these five mentioned zones, the Zagros zone shows the highest b-value (1.28 ± 0.03), and in contrast, the East-Central Iran zone shows the lowest value (0.84 ± 0.08). In addition, the contour map showing the spatial distribution of b-value over the region is presented. According to this map, some parts of the Iranian region such as the Central Iran and the Eastern Iran clearly act as resistant (rigid) blocks. In summary, the results of this research reveal that the study of the frequency-magnitude distribution of earthquakes can be reliably used as a tool to discover the seismic deformation patterns as well as different tectonic structures of the regions.
H. Nazari; J-F. Ritz
Abstract
The Taleghan Fault is located at the southern side of Taleghan valley in Central Alborz, 50 km north west of the Tehran mega city. Usually described as a south-dipping reverse fault, it could be the source of some of the strongest historical earthquakes recorded in the Tehran region, notably the 958 ...
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The Taleghan Fault is located at the southern side of Taleghan valley in Central Alborz, 50 km north west of the Tehran mega city. Usually described as a south-dipping reverse fault, it could be the source of some of the strongest historical earthquakes recorded in the Tehran region, notably the 958 AD (estimated magnitude M 7.7). The fault stands out as one of the major active structure menacing the cities of Tehran and Karadj, representing together 12 millions inhabitants. In order to analyze the recent activity of the fault, a morphological study was carried out along the fault combining satellite imagery, aerial photographs and Digital Elevation Model. We found out an active branch that had never been described whereas the fault classically mapped appears inactive. Detailed field work along the branch allows us to show that the fault had its vertical component recently reverted from reverse movement to normal movement. One of the measured ratios of accumulated horizontal / vertical displacements associated to the left lateral and normal movement is 2.5-5. The strike, estimated dip and rake in the eastern part are 105°, 60° and 40° respectinely making it a left lateral- normal strike slip fault in this part of the Central Alborz.
R. Azimi; K. Seyed-Emami; A. Sadeghi
Abstract
The calpionellid biozonation within Shal and Kolur Formations in Shal region, SE Khalkhal are accomplished based on standard biozonation of Allemann et al. (1977). In this study, 5 biozones are introduced from Tithonian to Hauterivian:biozone. Biozone 1 belongs to Shal Formation ...
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The calpionellid biozonation within Shal and Kolur Formations in Shal region, SE Khalkhal are accomplished based on standard biozonation of Allemann et al. (1977). In this study, 5 biozones are introduced from Tithonian to Hauterivian:biozone. Biozone 1 belongs to Shal Formation and biozones 2 to 5 to Kolur Formation: 1- Crassicollaria intermedia Taxon Range Zone; Late Tithonian, 2- Calpionella alpina Acme Zone; Early Berriassian, 3- Calpionellopsis simplex - Calpionellites darderi Interval Zone; Late Berriassian to Early Valanginian, 4- Calpionellites darderi - Tintinopsella longa Interval Zone; Valanginian, 5- Tintinopsella longa - Tintinopsella carpathica Interval Zone; Late Valanginian- Hauterivian. Biozone 2 is also subdivided into the Calpionella alpina and Calpionella elliptica Subzones. Biozone 3 is subdivided into the Calpionellopsis simplex and Calpionellopsis oblonga Subzones. Based on this zonation, the Jurassic /Cretaceous boundary (Tithonian/ Berriassian) is defined at the Lower boundary of the Calpionella alpina zone which is equivalent to the Shal and Kolour Formations boundary.
R. Shabanian; D. Vachard
Abstract
Carbonate sediments of Permian age crops out in different parts of Iran. based On the foraminiferal content, they are attributed to Bolorian (?) ,Kubergandian to Dorashamian stages.These biogenetic limestone have plenty of Fusulinaceaa, non-fusulinid smaller foraminifers ...
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Carbonate sediments of Permian age crops out in different parts of Iran. based On the foraminiferal content, they are attributed to Bolorian (?) ,Kubergandian to Dorashamian stages.These biogenetic limestone have plenty of Fusulinaceaa, non-fusulinid smaller foraminifers and algae, and they are a basis for determination of age, establishment of biozonation and paleogeography of Permian based on fusulind content. In some localities,chiefly in the north and northwest of Iran because of the distribution of Fusulinid are very rare paleoecological and paleo environmental factors.Despite these situation, smaller foraminifers, especially uniserial ones have a very important role in carbonate sediment make up, determination of age and reconstruction of paleoenvironment.In this paper, this important and crucial role of uniserial foraminifers is discussed.
M. H. Kholghi; M. Vossoughi Abedini
Abstract
Safakhaneh batholith, situated at 47 km southwest of Shahin Dezh, northwest of Iran, is located in the central Iran structural zone intersecting the Cretaceous rocks. The absolute age of the batholith, determined for the first time by K – Ar method, has been calculated ...
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Safakhaneh batholith, situated at 47 km southwest of Shahin Dezh, northwest of Iran, is located in the central Iran structural zone intersecting the Cretaceous rocks. The absolute age of the batholith, determined for the first time by K – Ar method, has been calculated 69.535 Ma. showing upper Cretaceous – Paleocene epoch and Laramide tectonic orogeny. Geochemical investigations of the batholith show that the major part of the batholith is of mantle magma, in which magmatic changes of the crystalline differentiation and contaminations have occurred. The crystalline differentiation has caused the formation of different rock types of quartz monzonite, quartz monzodiorite, tonalite, granodiorite and monzogranite respectively. Primary magma of the rocks is of calc - alkaline and generally metaluminous. The specifications of batholith rocks can be compared with the I – Type Caledonian granites. From the tectonic point of view, the specifications of the batholith can be comparable with the volcanic arc granitoids (VAG).
H. Ghasemi; A. Ramazani; A. Khanalizadeh
Abstract
Silijerd intrusion with an age of Late Eocene – Oligocene (39.23.2 Ma) is located in Uromeyeh-Dokhtar magmatic arc, central Iran structural zone, northwest Saveh. This intrusion is composed of a continuous compositional range including: diorite/gabbro, ...
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Silijerd intrusion with an age of Late Eocene – Oligocene (39.23.2 Ma) is located in Uromeyeh-Dokhtar magmatic arc, central Iran structural zone, northwest Saveh. This intrusion is composed of a continuous compositional range including: diorite/gabbro, granodiorite, syeno-monzogranite and alkali granite intruded into the Eocene volcanic and pyroclastic rocks.
Variation diagrams showing trends of major and trace elements indicate a continuous compositional range and a comagmatic origin for these rocks. Trends of compatible- incompatible elements indicate the important role of fractional crystallization in the genesis of these rocks. All samples are metaluminous with medium-high K with calc-alkaline nature. High values of Rb, Sr, K, U, Th, Zr and Ba and high ratios of K2O/Rb and FeO/MgO indicate the similarity of the rocks of this intrusion with the rocks of continental margin magmatic arc intrusions. Depletion in Nb,P,Ta and Ti and enrichment in K,Sr,Rb,Cs and Ba are obvious in the spider diagrams of these samples. The enrichment in LILE and depletion in HFSE reveal the I-type metaluminous magmatism of volcanic arcs (VGA). Whole rock 87Sr/86Sr ratios of this intrusion range from 0.704759 to 0.705166 and it can be correlated with the values of these ratios in the mantle and lower crust sources and low contamination of their magmas with upper crust.
Existence of K-feldspar megacrysts and mafic microgranitoid inclusions in this intrusion, high abundances of La and Ce , V enrichement in mafic terms and low whole rock 87Sr/86Sr ratios of this body, suggested a partial melting of mantle wedge, subducted oceanic crust (metabasaltic sources) or lower continental crust (metatonalitic sources) origins for it. The discrimination tectonic setting diagrams also indicate an I-type continental volcanic arc magmatism for this intrusion.
