JOURNAL OF THE EARTH
Year:2009 | Volume:4 | Issue:2|Papers Count:14

The Middle to Late Cambrian deposits have several outcrops in Kerman Province - Central Iran. These deposits have been introduced as Kuhbanan Formation. This formation has a thickness of about 330 meters in east of Zarand city and has been studied for tidal facies analysis. The Kuhbanan Formation is disconformably overlain with Ordo-Silurian clastic deposits and also the formation is disconformably underlain by the Top Quartzites of the Early Cambrian Dahu Formation. Based on stratigraphic studies, the Kuhbanan Formation is devided into 4 members in Zarand area. All deposits in members 1 and 3 and some deposits of member 4 were formed in tidal flats. Field and petrographic studies of the Kuhbanan tidalites led to recognization of carbonate, siliciclastic, and mixed carbonate-siliciclastic facies groups.Detailed facies analysis of the Kuhbanan Formation resulted in recognition of three sequences (3rd order cycles) equivalent to the second half of the Sauk Sequence. After a global sea-level rising in the Late Early Cambrian and during the expanding of shallow seas, these deposits were formed on the northern margin of the Gondwana Super Continent in a rift basin as homoclinal ramp facies.

For site location selection, it is necessary to study candidate land’s morphology and geology. This should include surface as well as underground structure. Such a study has been known as a required criterion for site selection, within passive defense measurements. It is necessary to all know geological active regions and enactive regions of the country in order to plan for land use there. Finding some safer places in order to hide facilities and installations, construct some buildings that could not be easily seen by enemy and sheltering people, would make them less vulnerable to threats and military actions. All these works would create a safe mental and physical environment to work and live insecurity. This would speed up development process for countries, regions and cities apply these requirements.Iran, like other rich countries which own energy resources, mines resources and human resources, may face many kinds of threat from outsiders and enemies. The eight year war that was imposed against Iran, offers enough evidences for threats may happen any time in the future. For these reasons, it is very important and necessary to study all our potentials, including geological, to defend ourselves against any threat. It is very important to study geological structure of different regions, and find suitable and different solutions according to regions’ geological characteristics. We need some well planned and designed plans to protect our people and all other national resources and national capitals from any expected military attacks. Using our knowledge on geology can help reducing damages and risks of military threats, or even natural disasters. Preparing for risk reduction, defiantly, can reduce damage and help to speed up reconstruction processes after any disaster. This can also, reduce reconstruction costs, and all can be account as national strengths, that will threat enemies and make them fully think before taking any decision to attack our country.

The Shirgesht Formation (Lower-Middle Ordovician) in northwest of Tabas contains 3 members with 925 meters thickness. It’s lower boundary with the Derenjal Formation is transitional and It’s upper boundary with the Niur Formation is disconformity.The study of the Shirgesht Formation led to recognition of one group of deep marine environment that consists of turbidity and basin plain facies. The turbidity facies of Shirgesht Formation consequence of erosion of facies of older formations (Lalun, Zagun & Derenjal) from the shallow and retransport to deep marine environment. The basin plain facies includes shale and in the stay condition overlying the turbidity facies.Turbidity and basin plain facies of the Shirgesht Formation and It’s fining upward sequences indicate that these deposits were sedimented in relatively deep marine environment (submarine fans and basin plain) on a suitable slope which turbidity currents could form.

The earthquake size distribution is generally considered to obey the Gutenberg-Richter law. In this study we have introduced the concept of the b value spectrum based on the moment method to investigate the deviation of the actual magnitude distribution of earthquakes in Hormozgan province, Southern Iran from this law. This enables us to describe characteristic features of the magnitude frequency distribution of earthquakes. We found also a simple relation between the  h value and the b value spectrum. Analysis using this scheme showed that the actual size distributions of earthquakes have large variations from case to case and sometimes deviate considerably from the widely assumed the Gutenberg-Richter formula.

Tabriz city, the center of Azerbaijan, a part of Central Iran province, in the northwest of Iran, is a seismotectonically active region, surrounded the study area. This region for which and probabilistic hazard analysis are performed, is sited between 44o, 32´- 48o, 00´E and 37o, 20´-39o, 00´N. The active fault map of the region is prepared as the first step. For this purpose, all active faults are recognized and their seismic and rapture parameters are determined. Correlation of fault orientation and earthquake epicenter distribution showed that there is a close relationship between them. Preparing the epicentral distribution map and calculating the seismogenic layer depths in the region are performed, the second step, using historical and instrumental earthquake catalog. Afterwards, for seismic hazard analysis, the seismic parameters of study region are determined and seismic zones classification is done using Arc GIS software. Maximum earthquake, seismic parameters, and occurrence rate are determined for each seismic zone. The probabilistic hazard analyses are performed using 3 different attenuation relationship, resulted in seismic hazard curves for Tabriz city, and seismic hazard maps with return periods of 50, 75 and 475 years for study area.

The Varamin Plain is situated 40 kilometers East of Tehran on the southern slope of Alborz mountain ranges and Comprising an area of about 1475 square kilometers. The Average of rain fall and evaporation are 171.9 and 2438.5 mm/yr respectively. The average of plain elevation is about 950 meters from sea level. Varamin aquifer included essential aquifer and perched aquifers. Perched aquifers settle over essential aquifer. Essential aquifer bed rock is Miocene Marl. Water table variations in Northern parts (around Jajrood River) are due to the decrease of aquifer feeding waters from Jajrood River and in the western parts in cases of increased surface flows with wastewater transport of southern part of Tehran city. In addition salt river existence can influence pollutant in Varamin aquifer. To determine hydrodynamics potential parameter in the Varamin plain, results were used from pumping wells in the recovery methods, also using experimental relations by Razack and Huntley. Razack and Huntley utilized a different approach in studying the relationship between (T) (Transmissivity) and specific capacity in an alluvial ground water. The yield of the well divided by the drawdown is called the specific capacity. This plain generally has extensive fertile soils. Years ago due to deviation of parts of Jajrod river path, and also pumping wells and withdrawing ground water resources, slowly caused the drawdown of water table level. The quantity and quality of ground water was provided by these changes.

The Senjedeh ore deposits in the Muteh region is situated in the central part of Iran. Because of Senjedeh is located in the central part of the Sanandaj-Sirjan zone had been taken several metamorphisms and deformations. Based on microscopic studies on the 112 collected samples from under studied region’s boreholes obtained very information about different genesis and forms of minerals and petrography. More senjedeh’s rocks are shear zones. By using of obtained these information and a Rock Work 2006 software plotted suberranean Petrography tridimensional modeling of region. With these models can be determined orogenic gold distribution in senjedeh’s rocks. Based on these models, schistose and gneissic mylonitic rocks are the much concentration of gold distribution 1 ppm and meta rhyolite are much concentration of gold distribution 3 ppm.

Reconnaissance and prospecting are two important stages in mineral exploration and geologists are prospecting mineral resources in these stages by using of surface data.Composing different layers in GIS is most important operation in these stages because it is helped for finding best areas for mineral exploration. In this paper, first, geology is contributed in this area. Next, faults and alterations were determined in the area by ETM+and Aster images. In next stage, geochemical exploration was operated and controlled by heavy minerals and mineralized samples that several primary anomaly areas were determined.Finally, after collection and composition geology, remote sensing and geological data in GIS system, 4 exploration targets were introduced for Au, W, Sn and Mo.

Seismic wave velocity study of crust and upper mantel is a significant key to understand earth’s structure. At some stage of past two decades, the seismic velocity of Zagros area has been studied. Results of previous studies are very important for identifying the seismic structure and authentic recent earthquake location in this active area. Based on 11472 seismic phases which were recorded in 13 seismic stations of Iran, Iraq and Kuwait, the average velocities are determined as follow: VPg=6.39 (km/s), VSg=3.87 (km/s), Vpn=7.89 (km/s) and Vsn=4.53 (km/s).

Since seismic field data is recorded in (x, t) domain in forms of its amplitude, it is critical to map them into (f, k) and process them in Fourier domain. A phenomenon that usually occurs over the signals in this domain is spatial aliasing. This phenomenon occurs for signals with high frequency and events with steep dips which cause the signals not to appear in their actual place. As a result, processing of the signals in this domain is invaded and has a direct effect on processes such as migration, thus methods have been introduced in order to eliminate or suppress spatial aliasing.In this paper we used the time shift method (Linear Move out) in (x, t) domain, which is skewed coordinate system. We have also introduced how to apply this method on real data and then the obtained results from their algorithm, have been presented respectively.

In seismic data processing to remove the effect of offset we apply the normal moveout correction. This correction does not perform well through the reflectors which have large dip or intersecting dips beneath the surface. In this case, to solve this problem dip moveout correction (DMO) is performed. Different procedures are performed to do this correction. They are DMO with Fourier transform, Integral DMO methods and DMO by Radon transform. The Radon DMO operator directly maps data from the NMO-corrected time domain to the DMO wave field in the Radon domain. The method is built upon a process that transforms a single NMO-corrected trace into multiple traces spread along hyperbolas in the Radon domain. These hyperbolas are a linear Radon map of the DMO ellipses in the time domain. In this paper, DMO by Radon transform are used for 2D synthetic data. According to results, Radon DMO is very good operation for amplitude and high frequency preserving and suitable for irregularly sampled dataset.

In this paper, it has been tried to study buried faults of Qom province using aeromagnetic data processing. Oasis montaj (4.1) software package is used to processes the primary aeromagnetic data. Then magnetic lineaments is extracted using reduction-to-pole and first order derivation in vertical direction in conjunction on the total magnetic intensity maps. Then the historical and instrumental earthquakes epicenters, filed data and processed Landsat satellite images is compared together to map the aeromagnetic lineaments for the province. This study show that the magnetic lineaments and sues face geological structures are correlated with each others. The suitable correlation of the earthquake epicenters and the extracted lineaments confirmed existence buried faults in some part of the study area. It is essential to consider the required preparations to develop any vital erections in this parts of study area.