ن&

Open Access Article

1 - The geometric and kinematic analysis of the Kabir-Kuh and Chenareh anticlines in the Zagros Fold-Thrust Belt
فاطمه زینعلی mohammad hosein goudarzi

20.1001.1.17357128.1394.9.34.2.6

Kabir-Kuh and Chenareh anticlines are located in the Lurestan Province of the Zagros fold-thrust belt. The geometry and kinematic evolution of folds in the Zagros fold-thrust belt are controlled by thrust faults. In this paper, the geometry of the Kabir-Kuh and Chenareh More

Kabir-Kuh and Chenareh anticlines are located in the Lurestan Province of the Zagros fold-thrust belt. The geometry and kinematic evolution of folds in the Zagros fold-thrust belt are controlled by thrust faults. In this paper, the geometry of the Kabir-Kuh and Chenareh anticlines is investigated in order to analyze their deformation style. To analyze the deformation style of these anticlines, five structural cross-sections were measured perpendicular to the axial surface trace of the anticlines. Based on geometric and kinematic analysis, Kabir-Kuh and Chenareh anticlines have a geometry similar to faulted-detachment folds with multi-detachment levels. The detachment level above which the folds formed is probably located in the Lower Paleozoic series. Also structural cross-sections represent an important contribution of the Dashtak Formation as intermediate level in the development of deformation in this part of the Lurestan Province. Manuscript profile

Open Access Article

2 - Tectonic geomorphology approach in the assessment of fold- growth mechanism within the Zagros Fold-Thrust Belt
آرش جمشیدی معصومه Vatandoust بهنام Oveisi علی فقیه

20.1001.1.17357128.1394.9.33.1.3

Zagros Fold-Thrust Belt consists of several fault–related folds which important hydrocarbon reservoirs are formed in relation to their evolution. Understanding of fold geometry and its growth pattern are affective parameters in the exploration and drilling programs of More

Zagros Fold-Thrust Belt consists of several fault–related folds which important hydrocarbon reservoirs are formed in relation to their evolution. Understanding of fold geometry and its growth pattern are affective parameters in the exploration and drilling programs of hydrocarbon reservoirs. In this research, stream bed erosion pattern and quantitative morphometric indices were used as geomorphic indicators to recognition the mechanism of fold-growth. Results of geomorphic investigation reveal dominant of detachment folding pattern in the coastal Fars area. Moreover, the effect of change in the thickness of detachment horizon on the folding pattern was evaluated. Manuscript profile

Open Access Article

3 - The role of the active tectonics in geomorphic anomalies of Gorgan Rud - Gharasu basin
Agh- Atabai Nemati معصومه روستائی

The study area is located in north of eastern Alborz range. In this study, it was evaluated the pattern of neotectonic in eastern Alborz and the distribution of seismicity and geomorphic pattern of Southern Golestan province. To assess tectonic activities in 22 separat More

The study area is located in north of eastern Alborz range. In this study, it was evaluated the pattern of neotectonic in eastern Alborz and the distribution of seismicity and geomorphic pattern of Southern Golestan province. To assess tectonic activities in 22 separated subbasins, we have analysed neotectonic indices: the stream– gradient index (SL), drainage basin asymmetry (Af), reveres symmetry of topography (T), hypsometric integral (Hi), drainage basin shape (Bs) and mountain front sinuosity (Smf). The results of the analysis is accumulated and expressed as an index of relative active tectonics (Iat), which divided into four classes from relatively low to highest tectonic activity. The high class values of tectonic activity for Iat mainly occur in the south and southwest of the Gorganrud- Gharasu drainage basin, while the rest of the study area has classes of Iat suggesting moderate to low tectonic activity. The rate of tectonic activity in this area will increase from north to south. This increase can be related to the position of peaks steam gradient index along the faults and segment faults. Also value of drainage basin asymmetry is calculated for all of the subcatechments greater or less than 50 that shows tilt for each stream toward West or East. The results of this study show that the distribution of seismicity, geomorphic and tectonic movements of studied area has been affected especially by Khazar and North Alborz faults movement and thrust fault in north of Gorgan. Areas with high tectonic activity and the high measure of tilting indicate that there may be a thrust fault, with a NNE-SSW approximate trend. On the other hand, this seismicity trend may be related to a deep and relatively young thrust splay in north of the Alborz range front. Manuscript profile

Open Access Article

4 - Morphotectonics and Paleoseismology investigation on Sahlan Fault Fragment, NW segment of the North Tabriz Fault
الهه احمدزاده Samane Aliakbar Nazari Talebian Solaymani Azad Marzieh Faridi Masouleh

The North Tabriz Fault is one of the major strike-slip faults (trending NW-SE) in NW Iran, that trends from Sofian to Bostan Abad. Generally, the fault consists of two main fault segments. In present research, to study the last active tectonics at the North Tabriz Fault More

The North Tabriz Fault is one of the major strike-slip faults (trending NW-SE) in NW Iran, that trends from Sofian to Bostan Abad. Generally, the fault consists of two main fault segments. In present research, to study the last active tectonics at the North Tabriz Fault region, evaluated young morphotectonical features and paleoseismology of northwestern fault segment evaluated. On the basis of morphotectonic approaches on this region, horizontal slip last event (MW = 7.4, 1780 AD) are found in the ranges 3.5 ±0.5 m and vertical slip between 0 and 0.5 m. However, by attention to H/V ratio can propose that NW segment of North Tabriz Fault act as pure strike slip which confirm by new GPS data on this part of Iran. On the basis of paleoseismological researchs, by examining a wall perpendicular to the North Tabriz Fault in North Sahlan Village, four old paleoearthquakes with relative magnitude of MW = 6.4 has been detected. A young magnitude of the event, recorded in deposits of the paleoseismologic trench of the study area, close to 7 have been estimated that according to geographic and stratigraphic location, this event can be associated with historical earthquakes since 1780 AD (MW = 7.4). Manuscript profile

Open Access Article

5 - Seismic hazard assessment of the city of Khoy using deterministic and probabilistic seismic hazard analysis approaches
Nasim Rahmani Abasfam

Construction of new cities or development of old towns in an area requires geological and geophysical (seismic) studies. The city of Khoy is one of the developing cities that have to be study. Therefore, the Deterministic and Probabilistic Seismic Hazard Analysis (DSHA More

Construction of new cities or development of old towns in an area requires geological and geophysical (seismic) studies. The city of Khoy is one of the developing cities that have to be study. Therefore, the Deterministic and Probabilistic Seismic Hazard Analysis (DSHA and PSHA) approaches have been used to assess seismic hazards and earthquake risk in the city. For this purpose, analyses have been carried out considering historic and instrumented earthquakes, geologic and seismotectonic parameters of the region covering a radius of 100 km with the city of Khoy in the center. Therefore, the main faults and fault zones in the study area were studied and length and distance of each fault from the center of the city of Khoy was calculated. At the next step, the Maximum Credible Earthquake (MCE) and Peak Ground Acceleration (PGA) have been measured using both DSHA and PSHA approaches and also equations presented by different researchers. DSHA Results show that the MCE and PGA values are 6.5 and 0.31g, respectively. PSHA results indicated that the MCE evaluated value is 6.1 for a 0.64 probability in a 50-years period. The period of this earthquake is 110 years and its probability will be 0.009 per a year. The occurrence probability of earthquakes with magnitude equal or greater than 7.1 is 10% and for earthquakes with magnitude equal or greater than 6.3 is 50% for the study area. Manuscript profile

Open Access Article

6 - Study of North West Sedimentary Basin of Iran by 3D Modeling of Gravity Data
Mojtaba Tavakoli Ali nejati

Inversion of the gravity data is one of the most interesting numerical tools for obtaining three dimensional geological images. In this paper 3D nonlinear inversion of the gravity data is used to determine the basement topography. The basement was juxtaposed with the re More

Inversion of the gravity data is one of the most interesting numerical tools for obtaining three dimensional geological images. In this paper 3D nonlinear inversion of the gravity data is used to determine the basement topography. The basement was juxtaposed with the regular array of rectangular prisms in which the thickness of each prism is determined by the inversion procedures. Prepared algorithm is based on singular value decomposition (SVD) method which ca modify the initial model by comparing observed and estimated gravity data. The SVD method is very popular with geophysical data analysts because it is mathematically robust and numerically stable. To illustrate effectiveness of the prepared codes and algorithm related to 3D inversion of gravity data, both synthetic and real data were tested by the mentioned algorithm. The real data were part of the gravity data which were acquired in Moghan area (located in the north-west of Iran). Because of being near to the Baku oil-rich regions and thick sedimentary rocks, the Moghan sedimentary basin is an interesting area from hydrocarbon exploration point of view. Determination of the sedimentary rocks thickness is an important factor in oil and gas exploration issues. The main goal of 3D inversion of the gravity data in the study area is to determine basement the sedimentary rocks thicknesses or the boundary of Ojagh-Gheslagh Formation and its volcanic basement. The modeled boundary of Ojagh-Gheshlagh Formation and its volcanic basement which is obtained by the inversion of gravity data, was previously confirmed by interpretation of seismic data. Manuscript profile

Open Access Article

7 - Investigation of geochemistry of minor and trace elements (rare earths) in the base metal vein mineralization Yaralujeh area (NW Ahar - East Azarbaijan)
Zohreh Jabarzadeh Mehadi Moradi Moayyed Zargar Faramarzi

The Yaralujeh vein index is located about 40 km NW of Ahar, East Azarbaijan. Based on geochemical studies, the original host rock is microdioritic in composition with calc – alkaline character, situated in an active continental margin volcanic arc. The mineralization i More

The Yaralujeh vein index is located about 40 km NW of Ahar, East Azarbaijan. Based on geochemical studies, the original host rock is microdioritic in composition with calc – alkaline character, situated in an active continental margin volcanic arc. The mineralization is occurred as disseminated, stockwork and veins - veinlets containing quartz, carbonate and sulfide minerals in altered subvolcanic rocks (microdiorite). Pyrite, sphalerite, galena and chalcopyrite are the most important sulfide minerals in this area. The most important alerations in this area are sericitic and carbonatization, and the main alteration minerals are quartz, sericite, illite, albite, kaolinite, leucoxene, pyrite and late carbonates. Bivariate diagrams of Ba + Sr vs. Ce + Y + La and Zr vs. TiO2 and also values less than one for TiO2 indicate a hypogenic origin for altered fluids. The spider diagrams of REEs, normalized to both chondrite and average upper continental crust, show differentiation of LREE from HREE and depletion of LREE relative to average upper continental crust. Based on geochemical indicators such as Hf / Sm, Nb / La and Th / La and LREE enriched relative to the HREE, the most important ion complexes transition metal are Cl- complexes. Ce, Eu and Pr (Eu/Eu*, Ce/Ce*, Pr/Pr*) anomalies in ore-bearing vein and host rock indicates near-neutral pH in a redox environment for the alteration fluids in Yaralujeh Index. Manuscript profile

Open Access Article

8 - Identification of Takab geothermal system reservoir by using gravity method
Mohammad Mohammadzadeh Moghaddam Javad Nouraliee Soheil Porkhial لیلا ابراهیمی Saba Moradalivand

The presence of hot springs, travertine outcrops, hydrothermal altered area and active tectonic in the north-east of Takab city in the West Azarbayjan province indicate that there is a geothermal system in the area. In order to characterize the geological structures ass More

The presence of hot springs, travertine outcrops, hydrothermal altered area and active tectonic in the north-east of Takab city in the West Azarbayjan province indicate that there is a geothermal system in the area. In order to characterize the geological structures associated to the geothermal system in the region, a gravity survey was carried out in 140 stations which covered an area about 600 km2. Necessary modifications such as Bouguer, topography and free air were applied over data to obtain complete Bouguer anomaly field. Then, residual gravity anomaly field was calculated by subtracting the regional gravity field from complete Bouguer field. The regional gravity field was calculated by fitting a three-order polynomials surface over the complete Bouguer field. The calculated residual gravity map shows two negative anomaly zones (A1 and A2) in the study area. In geothermal exploration, negative gravity anomalies are considered as probable reservoir of geothermal systems. The horizontal and vertical derivative maps show complicated fracture zones in the study area. To obtain more information, the depth estimation carried out using Euler method. Estimated depth for the top of negative anomaly source in zone 1 is between 1000 and 2000 m. Finally, 3D inversion of the data was performed using Li and Oldenburg algorithm to show an image of the reservoir in the depth. The results of 3D inversion show a significant negative density contrast that occurred only in zone 1. Therefore, the reservoir of the Takab geothermal system is located in the depths between 3000 and 5000 m in A1 anomaly zone. Manuscript profile

Open Access Article

9 - The Effect of uplift rate on geomorphic indices: insight to Misho Complex NW Iran
Mehdi Behyari Mohammad Mohajjal Mohsen Moayyed Mahnaz Rezaeiyan

The Misho Mountain is a prominent topographic feature in the North-West of Iran. This mountain is bounded with series of major active faults. Spatial array of these faults caused an uplift in the study area, and exposure of Kahar Formation in the core of the mountain. T More

The Misho Mountain is a prominent topographic feature in the North-West of Iran. This mountain is bounded with series of major active faults. Spatial array of these faults caused an uplift in the study area, and exposure of Kahar Formation in the core of the mountain. The active deformation affected topographic feature and changed the uplift rate. In this research we tried to quantify variation of uplift rate by using geomorphic indices and thermochronometry data. The analysis of stream length gradient, mountain front morphology, valley shape, and basin morphology indicated that uplift rate decreased from North to South and West to East. Hypsometric integral, which was calculated for the northern and southern flanks of Misho Mountain, also shows mature stage for the Southern flank, but in the Northern Misho tectonic activity increased and consequent;y show unstable state. Comparing between maximum and minimum swath profile in the west, central and east Misho indicated that in the west Misho the min and max swath profile indicate greater difference and show rapid uplift in the west Misho. Thermochronologic data show that rapid exhumation commenced by 21-22 Ma (Miocene), and an uplift rate of 0.16 to 0.24 Km/Ma was estimated. We propose that the range might be exhumed diachronously along strike and the magnitude of exhumation decreases to the ESE. This result is supported by structural and stratighraphy of study area. Manuscript profile

Open Access Article

10 - Analysis of tectonic seismic activity in the Tabas area
Razieh Abbaspour Seyed Morteza Mousavi Mahmoureza Heyhat

Independent estimates of deterministic and probabilistic methods of hazard analysis in the region of Tabas City were conducted in this study . Gutenberg - Richter relation for Tabas was obtained by analyses of seismic data based on LogN= 2.3 - 0.50 Ms. The greatest hori More

Independent estimates of deterministic and probabilistic methods of hazard analysis in the region of Tabas City were conducted in this study . Gutenberg - Richter relation for Tabas was obtained by analyses of seismic data based on LogN= 2.3 - 0.50 Ms. The greatest horizontal acceleration on Tabas city is 0.7g rsulted from Shotori thrust with a shaking power of 7.4 Richters. The obtained results show that, Kalmard fault with length of 170 km and distance of 50 kilometers from Tabas, has the highest impact after Shotori thrust. So that, the most expected seismic (8.93 Richter), the maximum relative intensity at the center (8.32), the maximum horizontal displacement at the center (29.82cm) and the maximum vertical displacement (66.70cm) are the result of this fault on Tabas. Using geostatistical analysis tool in ArcGIS (ordinary kriging), a suitable model was introduced for mapping the maximum gravitational acceleration. Using this map, zones with high and very high seismic risks and two liner earthquake sources with NE- SW trend (west of Tabas) as a result of Kalmard and Ladar faults and NW-SE (east of Tabas) as a result of Shotori, Esfandiar and Nayband faults were identified. Manuscript profile

Open Access Article

11 - Neotectonic zoning using morphometric indices in Lali – Gotvand area, Khuzestan
Tayebeh Ahmadi Aziz Rahimi Hojahallah Safari Arash Barjasteh

Quantitative assessment forms and effects of the Earth's surface and calculation of morphometry indices of rivers, river channel, and mountain fronts are the best methods for investigation of the active tectonics. The studied area is located in Dezful Embayment zone of More

Quantitative assessment forms and effects of the Earth's surface and calculation of morphometry indices of rivers, river channel, and mountain fronts are the best methods for investigation of the active tectonics. The studied area is located in Dezful Embayment zone of the Zagros Simply Folded Belt. In this study, the tectonics and regional morphotectonics of Lali – Gotvand area are interpreted using digital elevation model. This research analyzed three indices including mountain front sinuosity (Smf), ratio of valley width to valley height (Vf) and stream length-gradient index (Sl). The morphometry indices were analyzed to determine tectonic activity according to general tectonic of Simply Folded Zagros and Dezful Embayment in Lali - Gotvand region in the north east of Khuzestan. After calculating the noted indices and information integration layers, the neotectonic zoning map were prepared as tectonic activity in 4 categories: very active, active, relatively active and non-active. According to these results, maximum tectonic activities have occurred in the North East based on stream length-gradient index, in East, North East, South East based on ratio of valley width to valley height and in North East, South East and central part based on mountain front sinuosity, respectively. The neotectonic zoning map shows the highest activity in the North, North East and Center and the lowest activity in the South of the study area. Manuscript profile

Open Access Article

12 - Assessment of the activity in the gap zone of the Rudbar Fault, based on the morphotectonic indices of the Sefidrud River, Gilan Province
Shoja Ansari

In this study the morphotectonic indices for a specified length of the Sefidrud River, which is located in the meizoseismal area of the 1990 Rudbar earthquake, have been investigated to constrain the activity of a gap between the Rudbar Fault segments. The Digital Eleva More

In this study the morphotectonic indices for a specified length of the Sefidrud River, which is located in the meizoseismal area of the 1990 Rudbar earthquake, have been investigated to constrain the activity of a gap between the Rudbar Fault segments. The Digital Elevation Model (DEM) with 30 m resolution was used to obtain the elevation data. Fifteen km of the Sefidrud River also was divided into 100 -meter segments to calculate the morphotectonic indices. The morphotectonic indices include the sinuosity (SI), stream-length gradient (SL) and river long profile. The sinuosity in this region, where the trend of the Rudbar fault cut across the river, is approximately 1-1.5 and has a lower value relative to the other segments of the river. This indicates that the uplift possibly affected this region and then indicates the high tectonic activity. The stream-length gradient in the target region is approximately >3000 and has a higher value in the region which may be related to the lithological and active tectonic effects. The high value of SL can be used for determining the regions with high potential for the landslides along the strike of the Sefidrud River. The Sefidrud long profile, in aforementioned area, has a bulge or convexity. Such convexity together with the high value of stream-length gradient can indicate that the tectonic activities are significant in this region. By comparing the morphotectonic analysis with the seismotectonic studies such as the Coulomb stress changes due to the 1990 Rudbar earthquake, in which the high stress zones were detected in this region, it can be cluded that the studied region has high tectonic activities and consequently its monitoring to prevent the seismic hazard is essential. Manuscript profile

Open Access Article

13 - The geometric analysis of Burkh Anticline, the southeastern of the Zagros fold-and-thrust belt
Ramzan Ramzani Umali Naser Hafezi Moghaddas Ahmad Nohegar Abdolvahab Afroogh

Burkh anticline with the WNW-ESE trending is located in southeastern part of the Zagros fold-and-thrust belt and 40 km to the north of Bastak in the Fars zone. In this paper, based on the field data, satellite images and construction of the seven structural cross sectio More

Burkh anticline with the WNW-ESE trending is located in southeastern part of the Zagros fold-and-thrust belt and 40 km to the north of Bastak in the Fars zone. In this paper, based on the field data, satellite images and construction of the seven structural cross sections, structural geometry of the Burkh anticline is presented. Presence of the Precambrian- Cambrian of the Hormoz salt Formation as a basic detachment layer decouple the folded sedimentary cover from basement. Structural data show that the Burkh anticline is a detachment, buckle, asymmetrical and disharmonic fold. For describing tightness geometry of the fold, the term “open” is suggested. Field study and structural cross sections show that the Dashtak Formation as a middle detachment layer is the controlling factor for development of small-scale folding. Based on top of the Dehram Group underground contour map, vertical closure about 1000 m and horizontal closure of 200 km2 were calculated. Manuscript profile

Open Access Article

14 - Geochemistry of ore facies and alteration zoning pattern of the Varandan Ba-Pb-Cu volconogenic massive sulfide deposit, southwest of Qamsar
Fayegh Hashemi Fardin Mousivand Mahdi Rezaei-Kahkhaei

The Varandan Ba-Pb-Cu deposit is located in southwest of Qamsar which is part of Urumieh-Dokhtar magmatic-arc zone. Mineralozation occurred as four sub-horizons in the unit1 of volcaniclastics and volcanics (acidic tuff and andesite) of Middle-Late Eocene. Each sub-hori More

The Varandan Ba-Pb-Cu deposit is located in southwest of Qamsar which is part of Urumieh-Dokhtar magmatic-arc zone. Mineralozation occurred as four sub-horizons in the unit1 of volcaniclastics and volcanics (acidic tuff and andesite) of Middle-Late Eocene. Each sub-horizon consists of five ore facies including: 1) stringer zone, 2) vent complex zone, 3) massive zone, 4) bedded-banded zone and 5) hydrothermal-exhalative sediments of Fe and Mn bearing. Main wall rock alterations in the deposits include chloritic-quartz and quartz-sericitic. Alteration zoning is observed in the deposit as chloritic-quartz at the core and quartz-serisitic in the margins of the footwall of the ore sub-horizon. Electron microprob analysis (EPMA) on the chlorite in stringer zones of the second and third sub-horizons show that these chlorites are Fe-rich chlorite and close to the clinochlor field. Geochemical studies indicate that grades of Ag, As, Cu, Sb and Sr in the stratiform ore (bedded-banded and massive) of the third sub-horizon are much higher than the other sub-horizons, and are 41, 273, 1945, 390 and 1013 ppm, respectively. All geochemical studies show that metal zoning in this deposit is clear, this is characteristic of VMS deposits. Development of zone-refining and over refining processes caused leaching of Cu from the stringer zone and vent complex facies and its later precipitation in the bedded ore facies. Among across to different sub-horizons in the Varandan deposit, third sub-horizon is recognized as economic for Ag extraction . Manuscript profile

Open Access Article

15 - Seismotectonics of the west of Golestan province, the east of south Caspian region
Maryam Agh-Atabai Marjan Tourani

Golestan province is located in one of the seismically active zones of Iran. The seismicity maps of Golestan province show that density of earthquakes in the west is more than the east. In this research, the parameters including b-value, recurrence time and seismic mome More

Golestan province is located in one of the seismically active zones of Iran. The seismicity maps of Golestan province show that density of earthquakes in the west is more than the east. In this research, the parameters including b-value, recurrence time and seismic moment were studied to investigate the seismicity of the west of Golestan province. The focal mechanism of earthuqakes and field data were used to determine the stress orientations in the study area. The estimated b-value is obtained as 1.24±0.2 which is comparable with the Alborz. Since the northern and southern parts of the study area have different geomorphological and structural characteristics, some of these parameters were calculated for two subdivisions; Dasht-e-Gorgan in the north and foothill in the south. Results of this study show that the earthquakes in the Dasht-e-Gorgan compared to the foothill are smaller with shorter recurrence times. For the foothills, the calculated P-axes using the stress tensor inversion method is found to be subhorizontal with trend N-NNE. For this region, at least two trends, N and NW, is calculated using field data. This result show the change of stress directions during the structural evolution of this area. The calculated p-axes trend for the Dasht-e-Gorgan is NE. In both studied areas, the focal mechanisms of greater earthquakes are consistent with the E-W to NE-SW trend of main faults especially the Khazar fault. But, the smaller events in the Gorgan Plain show a different trend and mechanism. Comparison of these two subdivisions shows that the northern Alborz foothill is more dangerous than the plain. Manuscript profile

Open Access Article

16 - Tectonic geomorphology of Karkheh River Basin (West Iran)
Negin Rahimi Mehran Aryan Manouchehr Ghoreshi

Geomorphic indices are major tools to recognize tectonics activities. These indices have the advantage of being calculated from Arc GIS package over large areas as reconnaissance tool to identify possible geomorphic anomalies related to active tectonics. In this resea More

Geomorphic indices are major tools to recognize tectonics activities. These indices have the advantage of being calculated from Arc GIS package over large areas as reconnaissance tool to identify possible geomorphic anomalies related to active tectonics. In this research, Karkheh river basin was selected and six geomorphologic indices; drainage basin asymmetry (Af), stream-gradient index (SL), drainage basin shape index (Bs), mountain-front sinuosity index (Smf), valley floor width-height ratio (Vf) and hypsometric integral (Himatter) were calculated. Then, the values were classified in three groups and analyzed. The area of the three class as follows: Class2) 12180 km2, 23.7% Class3) 32318km2, 62.9% Class4) 6843km2, 13.3% The region has an area of about 51341 km2, so this result presents the moderate relative activity in the extensive parts of the area. Manuscript profile

Open Access Article

17 - The main effective factors on the mineralization of Sonajil porphyry-epithermal copper-gold deposit, using remote sensing, mineralogical and geochemical studies
Mohammad Maanijou

In order to identify the main effective factors in the Sonajil Cu-Au porphyry-epithermal deposit, remote sensing, mineralogical and geochemical studies were carried on the deposit. After removing vegetation and topographic features by Normalized Difference Vegetation I More

In order to identify the main effective factors in the Sonajil Cu-Au porphyry-epithermal deposit, remote sensing, mineralogical and geochemical studies were carried on the deposit. After removing vegetation and topographic features by Normalized Difference Vegetation Index (NDVI), solar radiance, instrumental errors and albedo effects by Log Residual (LR), Band Ratio (BR), False Color Composite (FCC), Principal Component Analysis (PCA) and Mixture-Tuned Matched-Filtering (MTMF) were used to reveal main alteration zones of the study area. The phyllic, advanced argillic and propylitic altered rocks were identified and the results were validated by field and mineralogical studies. Also, geochemical data showed microdiorite, and shoshonite composition and also post-orogenic tectonic setting of the Sonajil porphyry-copper deposits. Eventually, the faulting density, composition, and the depth of mineralization were the affecting factors on the Sonajil deposit mineralization. Manuscript profile

Open Access Article

18 - Difference of in situ stress regime dependent on Structural position and geomechanical characteristics, Case study- Gachsaran and Asmari formations, SW Iran
Hossein Talebi Seyd Ahmad Alavi Mohamad Reaz Ghasemi Shahram Sherkati

Estimation of in-situ stress tensor in sedimentary basins using information obtained from exploration and development oil and gas wells during the drilling and logging process may be used for estimation of in-situ stress tensor in sedimentary basins. The in-situ stress More

Estimation of in-situ stress tensor in sedimentary basins using information obtained from exploration and development oil and gas wells during the drilling and logging process may be used for estimation of in-situ stress tensor in sedimentary basins. The in-situ stress magnitude and orientation and the resulting stress regime around the studied wells have been several application in secondary recovery programs from hydrocarbon reservoirs as well as wellbore stability analysis. In this paper, the magnitude of in-situ stress is estimated by using abovementioned data in some oil wells located in the south west of Iran. Increasing the oil production by hydraulic fracturing design and sand control in the multi-layer reservoirs such as the Marun giant oil field with loose sand horizons and also improving drilling performance in the Gachsaran formation¬ requires knowledge about the prevailing stress conditions. This research, tries to analyze the stress regime of the Asmari and Gachsaran Formations around the selected wells in the Marun and Lali fields using constructed Mechanical Earth Models (MEM) and their differences are discussed. The calculated stress magnitudes in studied wells indicate a significant drop in magnitude of horizontal stresses from the Gachsaran to Asmari reservoirs in the Marun oil field. The magnitudes of the three principal stresses resulted that SHmax is the maximum principal stress and the Shmin is the minimum principal stress, thus a strike-slip stress regime (SHmax>Sv>Shmin) dominates in the Gachsaran sequence and the Asmari formation of the Lali oil field. however, in the Gachsaran formation of Marun giant oil field, stress regime is reverse-strike slip but normal stress regime is dominated in it's Asmari reservoir. The In-situ stress condition indicates that the structural condition and the depth difference of these structures plays an important role in the tectonic stress regime changes. Manuscript profile

Open Access Article

19 - Active Tectonics Zonation in Saveh Area, SW Tehran
bijan abdollahi Hossein Hajialibeigi

Geomorphic indexes can be a useful tool for investigating the impact of active tectonics and the identification of related anomalies, especially in areas that quantitative research work has been done. The study area is a part of the Central Iranian structural-sedimentar More

Geomorphic indexes can be a useful tool for investigating the impact of active tectonics and the identification of related anomalies, especially in areas that quantitative research work has been done. The study area is a part of the Central Iranian structural-sedimentary zone, located in the Saveh area. By studying the geological and topographic maps and using digital elevation data, it was evaluated the rate of relative active tectonics of this area, using some of the geomorphic indexes such as Hi, Re ,Bs, AF, Vf, Vc, V, SL, Smf and Iat. These indexes which have been measured and compared in eight fronts and nine basins (Shur-payeinii, Lar, Bidlu, Amirabad, Shur-baleii, Eshtehard, Buin Zahra, Arab and Kharrud) resulted to present the active tectonic zonation map for the study area. The measured Hi index shows the relative maturity of all basins and the Arab basin has the most relative tectonic activity compared to other basins. The Re index shows the highest elongation for Lar, Bidlu and Kharrud basins and the least elongation for Shur-payeinii basin. The AF index shows the highest uplift for the Bidlu basin, which is located on the right side of this basin. Vf, Vc and V indexes represent the lowest rate of activity in the valleys which are located on the border between the Shur-baleii and Amirabad basins, the southern part is the Lar basin and the border between Amirabad and Bidlu basins. The Kharrud, Buin Zahra and Arab basins are the most active basins based on the SL index. The Smf index indicates the high activity for all basins. According to active tectonic zonation map, it is possible to show that on the border between the Eshtehard, Shur-baleii, Lar, Bidlu and Amirabad basins which are located in 1 class, have the highest degree of activity. These basins are affected by behavior Jaru, Gomorkan, Ipak, Takidagh, and Alishar faults. Other parts along the mountain fronts are also located in 2 class and are active. The low-lying areas (Kharrud, Buin Zahra and Arab basins) located in 3 class, have the least degree of activity. The highest rate of SL index is for Kharrud, Buin Zahra and Arab basins. This high rate resulted to the seismic and active Ipak fault. According to Smf index, Amirabad basin is the most active basins. Vf index represent the lowest rate which are located on the border between the Shur-baleii and Amirabad basins. This border is located on Jaru and Gomorkan faults. Manuscript profile

Open Access Article

20 - Occurrence of copper mineralization of Abgareh deposit based on geology, mineralogy and geochemical evidences, south of Damghan
Raziyeh Mahabady Mohammad Hassanpour sedghi

The Torud-Chah Shirin volcanic-sedimentary arc, in the south of Kavir-e-Chah Jam depression (SE of Damghan), hosted many Pb, Zn, Cu, Ag and Au occurrences and deposits. Abgareh copper deposit is located in the northeastern part. Field and petrographic studies indicate t More

The Torud-Chah Shirin volcanic-sedimentary arc, in the south of Kavir-e-Chah Jam depression (SE of Damghan), hosted many Pb, Zn, Cu, Ag and Au occurrences and deposits. Abgareh copper deposit is located in the northeastern part. Field and petrographic studies indicate that deposit area consist of andesite, basaltic andesite and basalt rocks and to a lesser extent crystal tuffs with a middle–upper Eocene age. The rocks are of high-K, calc-alkaline to shoshonitic in nature, and are formed in a magmatic arc setting in a subduction zone. According to the field observations and mineralogical studies, the mineralization in the region occurred in two stages: hypogene and supergene and weathering. Hypogen zone minerals are generally pyrite, chalcopyrite and bornite, while chalcocite, covellite, malachite and chrysocolla are considered as the main minerals in the supergene zone. Fractures resulting from faults in the rocks of the region created a favorable location for the influence of hydrothermal solution and it is considered as the main controller of mineralization. Most of the textures observed in the mineralization include vein-veinlets, open space filling, radial, replacement and disseminated forms. Geochemical studies indicate that copper has the most relative correlation with silver. Since silver has not been found as an independent crystalline phase, therefore copper was replaced by silver in chalcopyrite and chalcocite. Compared with chondrite and primitive mantle normalizing diagrams, the studied rocks show significant enrichment with respect to LREE and LILE and depletion in HREE and HFSE and negative anomalies in Ti and Nb elements. Based on the relevant diagrams, differential crystallization of mantle rocks had the essential role in the evolution of the studied rocks which were probably derived from enriched mantle. Based on petrography, structural control of mineralization, alteration type and its extention and simple mineralogy, it can be concluded that mineralization at Abgareh district has characteristics of an individual mineralization system. This system is related to evolution of hydrothermal fluid mineralization resulted in vein-type Cu mineralization. Manuscript profile

Open Access Article

21 - Estimating the rate of shortening and the role of decollement in western Kopet-Dagh deformation
Moayyed zahra Tashakkory Hossenzadeh Manouchehr Ghoreshi Asadolah Bayrami. J. A Mohsen Pourkermani

The kopet- Dagh zone undergone subsidence and deposition of sediments after middle Cimmerian orogeny in middle Jurassic to Eocene. Its shortening resulted from the Zagros orogeny in Paleogene. In order to identify the minerals at the detachments, XRD analysis was carrie More

The kopet- Dagh zone undergone subsidence and deposition of sediments after middle Cimmerian orogeny in middle Jurassic to Eocene. Its shortening resulted from the Zagros orogeny in Paleogene. In order to identify the minerals at the detachments, XRD analysis was carried on the samples of Shemshak and Chamanbid Formations. On the other hand, the estimated shortening in the west and central Kopet-Dagh in two north-south cross-sections, were calculated in the 3D software of Move-Midland Valley, using previous data, field observation, geological maps and satellite images. The study of the three-dimensional cross sections, which is considered to be the innovations of this research, in the Move software has shown that most of the anticlines of the region are asymmetric due to the operation of detachment horizons. The results of the analyses indicate that the Shamshak Formation has more potential for developing detachment surfaces than the Chamanbide Formation. The reason for this detachment surface is due to thickness and mineralogy of the Shemshak Formation. On the other hand, by using geometric relationships, the depth of detachments was calculated for the main folds. In most of the detachments, this depth was calculated at lower levels of the Shemshak Formation. Manuscript profile

Current Issue

Published Issues

Menu

Browse

List of Articles ن&