Tectonics
Marzieh Rostami; Morteza Talebian; Abbas Bahroudi
Abstract
Anticline axes in both orogenic belts of the Zagros and Kopeh Dagh are offset by NW-SE trending transvers faults. These faults are rotating anticlockwise due to their oblique orientation relative to maximum stress vector, causing shortening across the belt and elongation along the strike. The transverse ...
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Anticline axes in both orogenic belts of the Zagros and Kopeh Dagh are offset by NW-SE trending transvers faults. These faults are rotating anticlockwise due to their oblique orientation relative to maximum stress vector, causing shortening across the belt and elongation along the strike. The transverse faults move right laterally and known as prominent faults of Bajgiran, Quchan, Shokranlou, Baghan in central Kopeh Dagh; and Kazerun, Karehbas, Sabzpushan, Sarvestan in central Zagros. Faults in two regions, however, show different pattern of offset. We proposed two different physical models, consist of rotating blocks at the base overlaid by sand with and without silicon layers, resembling variation of stratigraphy in two belts. In the Zagros model, where we have more incompetent layers, offset on the basement faults causes bending of the fold axes at the surface prior to any offset. While in the Kopeh Dagh, where we have less incompetent layers, the fold axes are offset with no major change in their orientation.
Economic Geology
Hasan Feizi; Sohelia Aslani; Farhang Aliyari; Abbas Bahroudi; Abdolhamid Sartipi
Abstract
The Khanik-Ghazan Titanium ore deposit is located at 82 km northwest of Urmia, northern Sanandaj-Sirjan zone. The main objective of this research is to identify potentially mineralized areas and to prepare a mineral prospectivity map in the Khanik-Ghazan deposit applying the Fuzzy Inference System (FIS). ...
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The Khanik-Ghazan Titanium ore deposit is located at 82 km northwest of Urmia, northern Sanandaj-Sirjan zone. The main objective of this research is to identify potentially mineralized areas and to prepare a mineral prospectivity map in the Khanik-Ghazan deposit applying the Fuzzy Inference System (FIS). After preparing the facto maps, the main stages of the investigation comprise the preparation of fuzzy factor maps using the appropriate linguistic variables and proper membership functions, combining factor maps using the fuzzy inference (by creating a fuzzy database of If-OR rules), identification of susceptible areas, and the generation of a potential mineral map using the output closure. In this study, in order to control the accuracy of the data, we tried to apply two new integrated methods including the fuzzy logic and hierarchical analysis processes. The results obtained from these methods was confirmed and complemented by each other and demonstrated highly potential mineralized zones. This statement is validated by several investigation methods including the field surveys and evidence of 80 samples collected from rock outcrops. Based on obtained results and modelling of geophysical data, the central part of the study area was recognized for further exploration using the drillcore subsurface exploration.
M. Fattahi; S. Rostami Mehraban; M. Talebian; A. Bahroudi; J. Hollingsworth; R. Walker
Abstract
Neyshabour (approximately 200,000 pop.) lies on the southern margin of the Binalud mountains in NE Iran. The city has been destroyed four times by major historical earthquakes (in 1209, 1270, 1389 and 1405 A.D.).Three large faults occur in the region. The Binalud and North Neyshabur faults ...
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Neyshabour (approximately 200,000 pop.) lies on the southern margin of the Binalud mountains in NE Iran. The city has been destroyed four times by major historical earthquakes (in 1209, 1270, 1389 and 1405 A.D.).Three large faults occur in the region. The Binalud and North Neyshabur faults lie at the foot of the Binalud range north of Neyshabour. The Neyshabour fault lies within the valley west of Neyshabour. The Neyshabour fault, which lies 10 km south of the North Neyshabur fault, is 50 km long thrust. At each end of the Neyshabour fault two young, 10 km-long, thrust segments occur. It is close to Neyshabour city; and is a probable source of the 1209 and 1405 earthquakes. It poses a substantial seismic risk to the city because of the potential for future activity. Slip rate is one of the important parameters for seismic hazard assessment which was determined using SRTM for offset measurement and OSL for age calculation. Luminescence was measured through 7 mm Hoya U-340 filters in a Risø (Model TL/OSL-DA-15) automated TL/OSL system. The equivalent dose (De) was obtained using the conventional quartz single aliquot regeneration method (Murray and Wintle, 2000). Twelve aliquots have been processed for the sample, of which only the aliquots were accepted that satisfied the SAR restrictions. De was estimated using analyst program. Age was calculated using a weighted mean De for the sample. The Dose rate was obtained using uranium, thorium and potassium concentrations, which were measured by Micro Nomand portable gamma spectrometer in field. The results are presented in Table 1. Dividing the displacement by the minimum and the maximum ages provided the slip rate to be 0.1-0.2mm/yr.
R. Nadri; M. mohajjel; A. Bahroudi
Abstract
The NNW-SSE striking Bidhand strike-slip fault system cut and displaced the Cenozoic volcanic and sedimentary rocks of the Urumieh-Dokhtar magmatic arc in south Qom. Structural evidences show that at least 16 km horizontal displacement in the Eocene volcanics has been caused due to dextral strike-slip ...
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The NNW-SSE striking Bidhand strike-slip fault system cut and displaced the Cenozoic volcanic and sedimentary rocks of the Urumieh-Dokhtar magmatic arc in south Qom. Structural evidences show that at least 16 km horizontal displacement in the Eocene volcanics has been caused due to dextral strike-slip movement along this fault. The compressional and extensional terminations were developed at the western block and not observed at the eastern one. The reverse and thrust faults associated with the drag folds were generated in the northwestern compressional termination and gabbroic sills were intruded in the southwestern extensional termination. Younger syenitic and granitic intrusive (Miocene) were intruded in the vacant space of the northern compressional termination and releasing zones along the central straight segments of the Bidhand fault. Gabbroic sills in the extensional termination at the south-western area of the Bidhand fault were folded and thrusted towards northeast due to the later deformational events.
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.
M. Asadi sarshar; A. Bahroudi; M. Qorashi; M. R. Ghassemi
Abstract
Estimate of moment rate is comparatively reckoned as a new method for dealing with tectonic activities rate in different regions and it prepares the way for putting together different methods. In fact, moment rate states rate of energy which exists in deformation system. There are three different approaches ...
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Estimate of moment rate is comparatively reckoned as a new method for dealing with tectonic activities rate in different regions and it prepares the way for putting together different methods. In fact, moment rate states rate of energy which exists in deformation system. There are three different approaches to state moment rate that each one express tectonic motion and movement of a region from a particular view. These three approaches consist of: geodetic (surveying), seismic and geology methods. Geodetic method which is determined on the basis of gained strain rate tensor from geodetic data, shows deformation rate (including seismic and aseismic) that is happening in the region at this moment in time. Moment rate which has gained on the basis of historical and instrumental catalogues, shows the total released seismic energy during quake events which are available in earthquake of region and geologic moment rate which gained with geometric parameters of faults, reveals potential of the faults in releasing stored elastic energy in. Geodetic moment rate, seismic moment rate (on the basis of historical and instrumental earthquake data) and geologic moment rate are estimated for Central Alborz region. The most moment rate in the study area belongs to geodetic approach (8.83×1019 Nm/yr) and then geologic moment rate (0.12×1019 Nm/yr) and finally the least quantity belongs to seismic moment rate (0.022×1019- 0.046×1019 Nm/yr). Considering, distribution of earthquake epicenters, the most seismic energy is released in the south parts of Central Alborz and considering high geodetic and geologic moment rates in north parts, it seems, north parts of Central Alborz have higher seismic potential.
G. R. Elyasi; M. Karimi; A. Bahroudi; A. Adeli Sarcheshme
Abstract
Piles of maps from different sources with varying scales and formats and different styles and absence of a proper solution for integrating vast amount of information has resulted in a complexity for preparing mineral potential map. Using GIS not only organizes the information related to mineral exploration ...
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Piles of maps from different sources with varying scales and formats and different styles and absence of a proper solution for integrating vast amount of information has resulted in a complexity for preparing mineral potential map. Using GIS not only organizes the information related to mineral exploration but also has the ability to produce and integrate information layers in different models with more precision and speed and supports spatial decision makings. In this article mineral potential map of Now Chun copper prospect has been produced for determination of drilling points. Used layers in this study include rock type, structure, alteration, mineralization indicators, anomaly zone of chargeability and apparent resistivity and metal factor, anomaly of copper and molybdenum and Cu-Mo additive indexes. After information preparation, Factor maps were weighted and integrated in the inference network. Integration use of Fuzzy logic and index overlay operators in inference network can eliminate defects in other models and provide more flexible integration of factor maps. Regarding to produce mineral potential map, mineral potential zones of porphyry copper were located in north-east parts of studied area. Eventually, the degree of correlation between mineral potential map and those operated exploration boreholes have been estimated for two different classes, 63.16 % and 64.52 %. Comparison between the high potential points indicated by our mineral potential maps with those previous drilled boreholes reveals about 26% discorrelation. It means that if such present study had been done before any drilling operation, it could have saved 200,000$ just for drilling expenditure.
M. Pirouz; A. Bahroudi; M.R. Ghasemi; A. Saeidi
Abstract
The study area is located in Zagros simply folded belt, south of Firuzabad city. We have considered sedimentary basin floor deformation, initial time of folding and salt structure upwelling by using isopach data. Moreover, these data can be used to indicate ...
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The study area is located in Zagros simply folded belt, south of Firuzabad city. We have considered sedimentary basin floor deformation, initial time of folding and salt structure upwelling by using isopach data. Moreover, these data can be used to indicate the expanding development. We have used NIOC isopach data for the Permian to Paleocene and Oligomiocene. If isopach data values are reversed and the 3D patterns calculated, they can show sedimentary basin floor shape. According to the 3D patterns, sedimentary basin evolution pattern, primary time of salt structures movements and basement faults movement in Firouzabad area were obtained. Mengharak basement fault with N-S trend activated with vertical displacement in the Permian and its movement changed left lateral strike slip after Triassic. In addition, extensional structures formed in the east of Mengharak fault continued to middle Cretaceous. At the same time, Neothetys was closed and the extension structures were converted to compression structures and also Mengharak fault movement changed to right lateral strike slip. Activity of salt structures (Jahani and Firuzabad) began in Permian and its activation increased during the Cretaceous in the Mengharak fault zone.
