JOURNAL OF THE EARTH
Year:2012 | Volume:6 | Issue:22|Papers Count:21

In this study, by using number of events contain explosions and natural earthquakes which were discriminated before, we tried to compare Mw/ML relationship between explosions and earthquakes. The data bank which used in this study contains 30 explosions and 69 earthquakes which happened in Tehran region (Long. 50o-55o and Lat. 35o-37o) between 2006 and 2009 and recorded by Iranian Seismic Telemetry Network (ISTN). All of these events are local and the range of their magnitudes are 1<ML<4. By calculating local and moment magnitudes we found that Mw/ML relationship is MW=0.765ML+1.099 for explosions and MW=0.681ML+1.369 for earthquakes. This comparison was done again on a smaller magnitude range of 1.1<ML<2.1 where the equation changed for earthquakes with MW=0.508ML+1.715, and in case of explosions, since all events were smaller than 2.1 (ML scale), the equation did not change.

Distinguish between heterogeneity and anisotropy effects are appropriate method to achieve accurate resistivity data interpretations. Since the anisotropy effects are weaker than inhomogeneity one so, we have to use a technique that is sensitive to anisotropy for removing heterogeneity effects.Azimuthal resistivity surveys increasingly are being used by hydrogeologists in the dentification and characterization of fractured rocks. It also can be used to detect anisotropy. The Arrow-Type array that we investigated here does show the highest sensitivity to anisotropy and can remove effects of near surface inhomogeneities. It also can distinguish between anisotropy and inhomogeneity as well. On the other hand, using a simpler logistic in the field will make this method more convenient in comparison with the other azimuthal arrays. Knowing exact place and direction of anisotropy helps us to achieve accurate interpretation; in addition it gives us convenient geological information. In this paper the Arrow-type array is determined first. We used this array in the field work to detect heterogeneities’ exact locations and to remove their effects on our data. We were able to obtain pure data for anisotropy investigation.

The Lorestan province structural position between the Sanandaj-Sirjan zone in north and the Zagros folded- uplifted belt in south are caused for controlling the province seismic activity. The Zagros faults are formed in the two zones contact, and there is the highest concentration of seismic activity. The oblique convergence Arabian plate and the Central Iran are caused for the Main Recent Zagros fault strike-slip movement with dextral component in the NW Zagros zone. The Main Recent Zagros fault activity is caused earthquake events with transtension focal mechanism in the north part of the Lorestan province. Also the north ward Arabian plate movement is caused compressive focal mechanism in the south part. The hidden faults activity under the thick sedimentary are caused to wide distribution earthquakes in the Lorestan. The Hormoz salt thick bedding between the Zagros basement and upper sedimentary deposits are barrier for influencing basement fault activity in the Zagros seismic activity. So such as the Zagros zone, the earthquakes depth character is low or maximum medium in the Lorestan area. According to this study in this paper, the maximum vertical acceleration is along the Main Recent Zagros fault in the Lorestan north part. Along this fault, vertical acceleration in the Aligudarz is 0.3 g, so compared to other Lorestan cities is more threatened.

Seismic tomography is powerful method in exploration of mineral and investigation quality of rock in underground. In this method by measuring velocity of seismic waves and plot the curves which have the same velocity, the quality of propagation of seismic waves between sources and receivers. Seismic tomography usually used to preparation section of physical distribution such as porosity, crushed, stratigraphy maps drawings and determining anomaly. Meanwhile by using seismic tomography, it is possible to investigate the existence of fault, cavity, mass densive, dike, lens and etc. in order to map the structure of the upper layers near the bedrock. In this paper the quality of riverbed in accordance to lithology parameters changes, the determination of crushed zone and the quality zone areas of the layers are analyzed by use of seismic tomography based on velocity of propagation of P waves at Rudbar Lorestan for constructing dam. In this paper seismic data obtained from several boreholes and galleries located at Rudbar Lorestan river dam site in the Iran, was used to model 2D tomography of the subsurface.

The fuzzy GK clustering method to detect random noise is presented by Hashemi in 2008. His goal was to attenuate the amplitude of the samples which have more contribution to the random noise by multiplying the lower weight factor to their values. Choosing the appropriate number of clusters is an important consideration for this method that is so effective in the output sections. The number of cluster is determined by a criterion which aims to decrease the within-cluster scatter and increase the between-cluster scatter in the feature space. We apply the algorithm more times, but by different number of clusters in each time, to consider the result of number of clusters in final output. The output sections show that by increasing the number of clusters, both data and noise are distributed in more clusters, so when we eliminate one cluster, the probability of missing the signal in seismic data is more less. It's the main advantage of high number of clusters. But we consider disadvantages like complicated computations and long time for running the algorithm. As the fuzzy GK algorithm is a semi-supervised method, it seems we must consider the main properties of the input data like SNR, real or synthetic, post stack or pre stack and also using existing indexes in method including XB index, signal index and comparison between output sections, to decide about any special case. Regarding all of them, we can hope to have the best output by the minimum amount of noise and good signal enhancement.

The Qom Formation (Oligo-Miocen) is the most important hydrocarbon source in central Iran. Deposition of the Qom Formation in Band-e-Amir section in northwest of Saveh was studied for stratigraghy survey, facies analyze and environmental interpretation. The studied area was located in structural-sedimentary zone in central Iran. The Qom Formation has a lot of facies variations. At the time of transgression, gypsum and marl were deposited and at the time of regression, limestone and marl were sedimented. Therefore, in most areas, the Qom Formation can have alternation of marl and limestone with intercalations of gypsiferous marl and gypsum. This formation has important role as a reservoir rock, source rock and cap rock. Band e Amir Section in northwest of Saveh have 198 meter of thickness. Assessment of thin sections of The Qom Formation in Band-e-Amir section led to recognition of three facies groups related to lagoon (A), barrier (B) and open marine environments. Lagoonal facies consists of packstone and wackestone textures. Reef facies have formed coral boundstones and barrier deposits. Open marine facies have shown turbidity and basinal characteristics. Lack of inertidal facies and abundance of talus and turbidity facies are the characteristics of the Qom Formation in the studied area. Assessment of lateral and vertical changes of facies show that the Qom Formation in Band-e-Amir section were deposited in a carbonate Rimed shelf.

The scope of study is in the map scale of 1.25000 of Kandelus from Mazandaran province and suburbs of Baladeh which is located in southeast of sheet of 1.100000 of Baladeh. This sheet is located in the sheets of Mazandaran province in the geographical scope of 51o30’44” to 51o36’04” of north width and 36o20’00” to 36o17’00” in southeast of topography sheet 1:50000 of Pul.In this study, we used waterway sediments method for geochemical discovery and sampling network is designed by considering some factors such as Lithology, fault and some other ones so that the maximum adaptation by the method of gravity center is obtained. The geochemical sampling was done from a scope by the area of 42 square kilometers. Mono-variable and multi-variable statistical processes such as calculation of integration coefficients, cluster analysis, factorial analysis and so on were executed over the data indicates operated enrichment and consequently the results were interpreted and explained. Thus through this way paragenzy complexes of chemical elements were identified. Also, mono-variable maps, factorial analysis, P.N specifications analysis were drawn for raw data and index of enrichment by applying the program of network estimating. Seven preliminary anomaly zones of geochemical data were introduced by combining the above mentioned maps. The phase for distinguishing the real anomaly from false anomaly and the appearance phase different elements through studies were determined from the combination of geochemical, heavy mineral, mineralization, density of fault and the results of geophysics and telemetry, and consequently 7 anomaly zones were introduced.

The main purpose of this article is to verify precisely the number and dispersion, dip, azimuth and strike and extension of fractures of Asmari formation and also to determine dip and strike of different zones of Asmari formation and determine the direction of old current in the Ahwaz well No. 186. Thus, one of the imaging tools (FMS) was used for achieving these goals. This tool has been designed in a way to help observer to see the vertical and lateral variations of formation characterization constantly and in detail. The electrical current recorded with microelectrodes after rereading offers some images that are similar to the images obtained from core and by utilizing these images one can recognize the dip and dispersion of fractures, structural dip. The average structural dip of Asmari formation in well#186 of Ahwaz oil fild was determined by FMS technique. The fractures of these reservoirs are generally divided in to a couple of groups. One is the longitudinal type and the other group is oblique fractures. There fractures also determine the maximum tension exerted on the well hole and the direction of old currents in the Asmari formation in Ahwaz well No. 186.

The studied area is located at south of Amol, Haraz road (north of Iran). Mangol dam which is investigating, is located at 20 Km from south of Amol. From tectonic point of view this area is located at north Alborz fault zone, several fault have affected dam area, like Mangol and Chelave faults. The important faults of this area are a kind of reverse and thrust with E-W straight, But normal and strick slip faults locally have been seen in N-S, NW-SE or NE-SW. Emarat anticline with dome structure consist the big part of this area. Faults of this area can be named as active faults, oscillating. regarding to the action of existing index faults in this part of north of the Al-borz fault zone can be said that the gradient of faults from the south to the north is increasing and the formation of thrust and reverse faults, shows compression in this area.

The Gandi gold deposit is located in 130km South East of Damghan city and 25km North East of Moalleman village. The area is part of central Iran structural zone which is limited between two major fault, Anjilou in North and Toroud in South. Gandi gold deposithave 337453.68ton ore with 5.18ppm gold grad, and wholly 1.69ton gold estimated for it. The rock host consist of alteration of tuff, sandy tuff, siltstone and marl with upper Eocene age which is thin bedded in lower parts and medium to thick bedded in upper parts. Northword, An East-West fault zone separated Gandi deposit from volcanic and pyroclastic rock with andesite, basalt and dacite component. The major fault system of the area have NE-SW trend and trends of NW-SE and E-W have miner preference. Due to infusion of hydrothermal solution in the faults and fractures of the area, mineralized veins are formed and host rocks are altered (kaolinitization, silicification and jarositization). Mostly, the mineralized vein trended NE-SW and they have carbonit-silica and brecciated ore, with Fe oxides in the syrface. Gold has seen as a free metal in the ore and also as onclosion in the sulfide minerals and as petzit mineral (mineral consists of Te, Ag and Au) in this area (Badakhshanmomtaz 2003). Sub intrusive activities are known as the responsible for the gnesis of this mineralization (Ford 2002, Goliyaee 2000).

Trough the study of Rare Earth Elements of Apatite Esfordy, the results of ICP.MS analyses indicated that five elements including Ce, Nd, La, Y, Pr are more abundant elements, in this mine and they have positive correlation index. In this mine light rare earth elements are more abundant than heavy rare earth elements. Total percentage of rare earth elements is 0.55 % and according to the production of concentration is 103000ton a year, total weight is 566.5tons in concentration. Considering the result of XRD analyses Fluor apatite, Quartz and Hematite are most minerals of input soil and concentration. Within old waste of this mine the amount of Fluor apatite is more than Hematite which is shows that in past processing did not perform correctly. In current processing Rutile, Dolomite and Coromite are separated from the input soil and are enriched in Calcite. Minerals related to REE include Fluor apatite and monazite, minerals related to bed rock include Quartz, Cordierite, Rutile and secondary minerals include Dolomite, Calcite, Olivine, Ankerite, Clinocolor and Gutite. Along with Apatite there are Monazite and Alanite, but less in quantity in which heavy REE of Bafgh Apatite is included.

In this paper, satellite images of Shiraz taken by Land Sat, have been processed by Erdas v.8.5 software, and then theirs obtained lineaments have been studied by Arc GIS v.9.2 software. By comparison of the obtained results with historical and instrumental recorded earthquakes as well as field testimonies and inspection of morphotectonic indices, positions of the active faults of the township were determined. According to this study, 34 of the fundamental faults of the township were identified in which only 25 faults are active through of them. These results obtained by field observations as well as the historical and instrumental recorded earthquakes with active faults position located in the area, illustrate that Shiraz township is prone to having seismicity.

The Lak lead mine is one of the ancient mine in Qazvin province. This studied area is located in Oromeye-Dokhtar zone in structural and tectonic geology divisions and the Eeocene volcanic rocks and lavas have the most extent in this area. The oldest rocks are related to Cretaceous and before it which are found in west-south of area.The main fractures of studied area have mostly NE-SW trend. Mining and high grade regions of this deposite are the veins that are formed in fault and joints. Remote Sensing studies indicate that mineralization are imitated (followed) from the trend of main faults and the Argillic and Iron Oxide alteration become evidence by enhancing satellite images.

The continuous wavelet transform (CWT) is one of the spectral decomposition methods to analysis a nonstationary signal in order to obtain an optimal time and frequency resolution of signals. Among spectral decomposition methods, the first method is the short time Fourier transform (STFT), in this way, time-frequency resolution is limited by predefining a window length. In contrast, the continuous wavelet transform method does not require preselecting a window length and does not have a fixed time-frequency resolution over the time-frequency space. CWT uses dilation and translation of wavelet to produce a time-scale map. Then the time-scale map of CWT is converted to a time-frequency CWT (TFCWT) map to obtain high time resolution at high frequencies and high frequency resolution at low frequencies. This property of the wavelet  transform is used for detecting thin layers.In this thesis, at first a synthetic wedge model is considered, then, the peak scale (frequency) and the peak amplitude of scale (frequency) are extracted from spectrums of CWT and TFCWT. Then, they are compared with each other. It is shown that attributes given by the TFCWT have better resolution in comparison to CWT spectrum. Then exercising the same procedure on real data.

The study area, in 40 km southeast of Eghlid town, is a metamorphozed terrain that is located between Eghlid fault and Zagros main Thrust and is a part of southeastern Sanandaj-Sirjan Zone. The area consist highly deformed rocks which have been emerge clearly in a dextral shear zone. Mesoscopic scale analysis carried out for determining the paleostress directions and deformation history of the area. Thus foliation and lineation structures measured and analyzed based on field study and statistical method. Then fitting structural models were offered for each of them. Furthermore, the formation ages of the structures were considered based on relative time scale. According to the results, it can be concluded that four different deformation phases were efficacious in formation of the analyzed structures.

This studied area is located in north east terminal of central Iran zone in the south part of Sabzevar zone and geologically is located in north magmatic arc of Doruneh fault. It is necessary to mention that the studied area, tectonically is effected by two fault behaviors, Doruneh fault in the south and Rivash fault in the north which are the most effective factors in constructing formations of fault and also high mineral potential in this area. Lithology of this area consists of volcanoclastic rock-units of lower Eocene age. On the basin of petrography and field observation the rock-units consisted of latiteandesites, trachyandesites to trachybasalts, rhyolits, agglomerates, tuff and shale intercalations. The wide spread alteration of the area include propylitic, argillic and sericitic facies. Now, considering to high sulfidations epithermal mineralization and dependent alteration, particularly progressive argillic and alunitization existing mixing in the area, production (originating) of gold in Cheshmeh Noghreh can be justified.