Researches in Earth Sciences
Year:2019 | Volume:9 | Issue:36 |Papers Count:12

The Jouzbon Cu index (~1. 5 wide and 100 meters’ length), at the south-southeastern parts of Damghan city belongs to the Torud– Chah Shirin volcanic belt. This belt contains calc-alkaline volcanic rocks. The Cu mineralization has occurred between two major faults, the Torud Fault at south and the Anjilu Fault at north. The volcanic and intrusive rocks in this belt include quartz-diorites, quartz-monzonites, dacites and andesites. These rocks show porphyritic, granular and poikilitic textures. The prevailing alteration phases of this region are characterized by sericitization, silicification, calcification, and propylitic alteration. The main mineralization phases of the Jouzbon region are dominanted by occurrence of the sulfides and oxide minerals including pyrite, chalcopyrite, galena, bornite and hematite. Secondary minerals such as covellite, chalcocite, malachite and iron hydroxide are also common. Geochemical observations show that the host rocks are related to a alumina-saturated calc-alkaline magma with volcanic arc (VAG) signature. Fluid inclusion studies on quartz testified a narrow homogenization temperature but a wide salinity, ranging from 130 to 190 ° C and 4 to 14. 5 wt% NaCl equivqlent respectively. Geothermometry assay, based on morphology of pyrite crystals, yielded a temperature in the range of ~250° C for the alteration zone. The compiled data testified that mineralization probably has occurred at the depth of ~ 100 meters below the surface during the epithermal conditions, similar to the IOCG-type deposits.

In present research geometric method using Surfer software and geostatistical estimation method have been used to evaluate sodium sulfate reserve in the central part of Mighan-Arak sedimentary basin. Using geometric method, average assay of the deposit and net ore reserve were calculated 25. 1 percent and 3223581. 7 tons respectively. In order to employ geostatistical method, first assay and thickness data of test pits, was statistically analyzed. The results of this stage showed a log-normal distribution for assay data and a normal distribution for thickness data. According to the results of variography and analysis of spatial structure, ordinary block log kriging was employed for assay data as well as inverse squared distance method for thickness data. By this method the size of estimated blocks was selected 60*58 m, average assay of sodium sulfate was obtained 24. 98 percent with average standard deviation of 1. 09 percent, average thickness of blocks was gained about 2. 57m with average standard deviation of 0. 23 m while the upper and lower limit of the mineral deposit are 5275221. 4 and 6286683. 8 tons respectively in the reliability surface of 95 percent. Based on the results of this research, the difference of calculated reserve by geometric method through Surfer software and kriging is 2557370. 9 tons that means 44. 2 percent. However the results of kriging estimation are highly accurate and more reliable due to be unbiased having minimum estimation error.

During one year, the Bardsir earthquake (2010/07/31, MS=5. 8), the Kahnooj earthquake (2011/06/15, MS=5. 7) and the Sirch earthquake (2011/06/26, MS=5. 2) have occurred in Kerman province (one of seismologically active area in eastern Iran). The earthquakes have been relocated and processed using local and regional recorded seismograms. Mechanism of the earthquakes were calculated using the first P motion method. Processing both locations and focal mechanisms indicate that these earthquakes are probably related to the Lalehzar, Sabzevaran and Golbaf fault systems, respectively. Bardsir and Sirch earthquake faults dip northeastward and Kahnooj earthquake fault dips eastward, indicating that both source faults dip steeply. Mechanisms of the earthquakes were right lateral strike slip, reverse with right lateral strike slip component and reverse mechanism, respectively. Finally, this research is in accordance to the field investigations, in which the maximum intensity in MM and JMA scales was estimated ~VI near epicentral area and no co-seismic surface rupture were detected for these earthquakes.

The objective of this research is an investigation on variations and relationship between different elements in soil and various plant species in Darreh-Zerreshk mining area and its comparison between elements distribution in barren zones. On the basis of this research can propose a suitable geochemical exploration for discovering hidden ore deposits in the district and peripheral zones. For this purpose, 32 samples from two different fractions of B-horizon of soil from mineralized and barren zones and 29 plant samples from different species were taken and after preparation were analyzed for copper, iron, lead and zinc by AAS analytical method. In the first stage by preparation and analysis of duplicate samples, the different stage errors were analyzed and concluded that the 3-acid dissolution procedure is the best preparation method and the precision of different steps are in acceptable range. In the next stage, the correlation between elements and their Biological Absorption Coefficients (BAC) were investigated. The recent study demonstrates that due to variety of species, dispersion and sparsity of the plants and the effect of different biological factors, the use of biogeochemical method as a tool in copper exploration in the area is challengeable. However, secondary lithogeochemical environment such as soil can be introduced as most suitable sampling environment because it can demonstrate the highest copper concentration in contrast between mineralized and barren zones.

The Asmanou deposit is located in 85 km east of Shahrood, in the Sabzevar zone and Toroud-Abbas Abad district. The host rocks of mineralization are pyroxene andesite, basalt, basaltic trachyandesite and trachybasalt which display shoshonitic affinity and characteristic of continental arc setting. The country rocks in the Asmanou variably altered and two type of alterations, regional and local, could be distinguished; zeolite-carbonate regional alteration is widespread in the area and local alteration associated to the mineralization are chloritic and hematitic. Mineralization occurs as vein and stratiform and the common textures are disseminated, vein-veinlet, stock work and open space filling. Chalcosite is the main ore mineral accompanied by subordinate magnetite, hematite, bornite, chalcopyrite, pyrite and secondary minerals including covelite, malachite, coprite and goethite. Nonmetallic minerals are calcite, quartz, chlorite and zeolite. Fluid inclusion studies from the calcite and quartz from the main hypogene stage yielded the homogenization temperature between 79 to 350 ° C for calcite, and 160 to 250 ° C for quartz. Salinities for calcite is between 2. 3 to 22 wt% NaCl eq. and for quartz between 6. 1 to11. 3 wt% NaCl eq. The results of this studies show the mixing and boiling are two important factors in the mineralization. Geophysical studies using resistivity (Rs) and induction polarization (IP) show the high values of IP-Rs in 5 to 40 m depth. Mineralogy, ore texture and structure, and fluid inclusion characteristics in the Asmanou deposit are similar to those manto type copper deposits.

In this research, two subsurface sections consist of well No. 2 and No. 3 from the Asmari Formation with a thickness of 423 and 412 m respectively in Chahar Bisheh oil Field have been studied. The Asmari Formation in this field consists of intermittent layers of limestone and dolomite, very thin shale layers and anhydrite interlayers. Based on petrographic studies and identification of microfacies, 15 microfacies and 1 lithofacies in 4 facies belts consist of tidal flats, lagoon, shoal and open marine for the Asmari Formation have been recognized and sedimentary environment of this formation, is a Homocline ramp carbonate platform. Effective diagenetic processes including cementation, dolomitization, compaction, fracturing, dissolution, micritization, pyritization, geopetal fabric, boring, silicification and neomorphism which has influenced the Asmari Formation by all three marine, meteoric and burial diagenetic environments.

Discontinuities are the most important property of rock mass that control the permeability. Effects of orientation, frequency and number of sets of discontinuities on the permeability investigated before and after improvement by grouting using cement grout in this study. Rock samples having one, two and three cross-sets of single discontinuities and three cross-sets of discontinuities with one set having four parallel discontinuities, in different groups of various orientations (angle between planes of discontinuities and horizontal direction) of 0, 30, 45, 60 and 90 degrees in total of 20 different groups that have been preparing. The permeability of 20 group samples with different orientation, frequency and number of set of discontinuities has been measured. Discontinuities of multiple groups of samples using cement grout improved and also their permeability measured. The results show that the effect of discontinuities’ s orientation on permeability changes by changing the number sets and the frequency of discontinuities. In samples having three cross-sets of perpendicular discontinuities with one set having four parallel discontinuities which have been represented jointed rock mass. Permeability is mainly affected by the orientation of the set that has four parallel discontinuities. Orientation, frequency and number of sets of discontinuities cause change in permeability about 759048 times. The permeability reduces in the range of 9-99% with the improvement of samples using cement grout injection. This indicates that the orientation, frequency and number of sets of discontinuities are very effective in reducing permeability by the injection.

Damghan Cheshmeh-Ali spring with average daily discharge of 140 lit/s plays main role in supplying the domestic and agriculture water demands in this area. In this study, daily precipitation and discharge data series from 2001-2010 were used for investigating of hydrological characteristics of the karst aquifer connected to this spring. Mangin’ s classification method indicates that the unsaturated zone of the Cheshmeh-Ali karst aquifer has more karstification degree compared to the saturated zone. Cross correlation analysis between cumulative rainfall (daily to 360 days) and daily spring discharge data indicated that the rainfall series of current day to 300 days have more correlation with the spring flow in current day. In addition, frequency analysis of drought hydrological carried out on the spring low flow and with duration of 3, 7, and 10 days indicated that discharge with probability of 99% is obtained as 350, 262, and 213 lit/s respectively for duration of 3, 7, and 10 days. Whereas, significant difference is observed between the predicted discharge with periods of 3, 7, and 10 days for less than 5 years return duration.

One of the most important environmental issues which can affect the health of plants, animals and humans is soil pollution by the concentration of the heavy metals. The increase of heavy metal concentration can occur due to the natural processes or human activities. The present study deals with examining and assessing the concentration and contamination of the heavy elements in the sediments. Roein basin in Esfarayen area was selected for this purpose and the concentration of 11 heavy metals, including As (Arsenic), Cd (Cadmium), Co (Cobalt), Cr (Chrome), Cu (Copper), Fe (Iron), Mo (Molibden), Ni ( Nickel), Pb (Lead), V (Vanadium) and Al (Aluminum) were measured in 42 samples and the correlation of the elements was examined. The results showed that there is a significant correlation between the copper and iron content (0. 99), iron and aluminum (0. 93), cobalt and copper (91), cobalt and iron (0. 89), chrome and nickel (0. 88), copper and aluminum (0. 85), cobalt and aluminum (0. 82), arsenic and aluminum (0. 72), nickel and lead (0. 7). Then, the contamination factors such as enrichment factor, contamination factor, modified contamination degree, pollution load index and geo-accumulation index were computed and assessed. All the indexes were calculated except the enrichment factor which depend on the elements existing on the crust of the earth and the arsenic is categorized as strong, suggesting that although the eleven elements studied contain various contents, they all are categorized as the non-polluting and therefore, there is no significant contamination in terms of heavy elements concentration in the area. Since, there is currently a higher increase in the heavy metal concentration, higher control shall be applied regarding the agricultural and industrial activities.

The formation and subsequent recharge of alluvial aquifers depend on the geological conditions, geomorphology, climate, and land cover. This type of aquifer plays main role in supplying the water needed by human societies in arid and semi-arid regions of the country and mainly due to excessive perceptions, they require the development and implementation of management plans. Alluvial aquifers in the Gilan-e-gharb have been equilibrium due to favorable environmental conditions until the mid-1970s. But gradually, due to human interference in the hydrology cycle of the region and the occurrence of dry periods, the Gilan-e-gharb aquifer falls to the surface and requires the formulation and implementation of management plans. In this research, modeling of alluvial aquifer susceptible habitats was performed based on six lithology parameters, linear density, drainage density, geomorphology, land use and slope. About 23. 8% of the area has a high groundwater abundance potential and 44% of the area has a low potential for groundwater and these areas are prone to runoff. Therefore, the special geomorphological and lithological conditions of the area have caused the natural recharge of aquifers to be limited and requires the implementation of artificial recharge plans.

One of the natural disasters that plays a major role in the vulnerability and destruction of rural settlements is earthquake. Vulnerability has a complex concept so that involves various factors and variables and using modern methods could improve vulnerability assess of the levels. The objective of this study is to vulnerability assess the levels and prioritization of rural settlements with the use of operators based on Fuzzy Logic. The Fars province was selected as a case study because of exist many major and minor faults, during the years occured huge earthquakes and theirs rural settlements have a variety of natural and human vulnerability. Because of the physical characteristics, rural areas exposured to high vulnerability is compared with urban areas. In this study, for vulnerability assess the levels and prioritization was used fuzzy operators that including multi criteria aggregation criterion importance and orders weight and two important properties consider to qualitative (linguistic) variables and according to various interest groups and also led to better results. Therefore, by using and aggregating various variables and scenarios, areas with high degrees of risk identified. Then rural settlements exposure risk resulting from relatively pessimistic scenario of natural vulnerability was choiced. Eventually, the human vulnerability of settlements have been prioritized using a moderate scenario. The results in all scenarios showed that South and West areas with high values of Peak Horizontal Acceleration, new geological formations and proximity to active faults as areas with high degrees natural vulnerability of risk has been identified and always happening huge earthquakes but from the perspective of human vulnerability variables is moderate.

The city-region concept which is against theories such as “ The death of distance” , “ The end of geography” or the emergence of “ weak economy” has recently become popular among academic and political elite. The city-region as the place of exchange, innovation, development and competition is an ideal area that identifies which economic competition can be promoted and cultivated. Hence, the identification of the context, the nature and reasons for the importance of the city-region pattern needs to be explained in an accurate manner. Various studies have been taken place on the city-region so far. In this paper using qualitative meta-analysis method, 45 scientific articles, published since 2000 are studied in a descriptive way and evaluated (in terms of questions, goals, and results). It seems that the necessity and application of this meta-analysis can be helpful in understanding the spatial nature of the city-region and identifying the role and position of it as a driving engine of the regions to balance and develop. The paper combines these scientific works and provides a structural-functional analyses of the city-region pattern for academic and executive policy-makers institutions.