مجله یافته های نوین زمین شناسی کاربردی
پیاپی 33 (بهار و تابستان 1402)

Degree of water saturation is one of the key parameters in petroleum geological engineering to calculate the volume of reservoir hydrocarbons and also reduce economic risk in the development of oil fields. The first attempts to estimate the degree of water saturation of the formation were made by Archi in the data of well drilling diagrams in clean sandstone reservoirs, the results of which were generalized as an experimental relation for carbonate reservoirs. In carbonate reservoirs, assuming these parameters to be constant due to severe heterogeneity is associated with a large error. On the other hand, it is not possible to calculate these parameters due to the time and cost and loss of part of the core for the entire length of the well. Artificial intelligence methods are new, low-cost and accurate methods that can indirectly estimate the degree of saturation of the reservoir water in the shortest possible time using well data. Therefore, in this study, using different wells and intelligent method of adaptive neural-fuzzy inference system (ANFIS-FCM), the degree of water saturation in one of the hydrocarbon reservoirs in southwestern Iran (North Azadegan Square) has been indirectly estimated. To use this artificial intelligence method, the database consisted of 2511 well data, which were divided into two parts: training data (1758 data) and test data to evaluate the models (753 data). The results show the very good performance of the adaptive neural-fuzzy inference system (ANFIS-FCM) method of estimating the degree of water saturation. Therefore, the adaptive neural-fuzzy inference system (ANFIS-FCM) model can be used as a powerful, fast and accurate method for indirectly estimating the degree of water saturation in reservoirs where the degree of water saturation is not measured through the core.

Zavarian gold deposit is located 60 km SW of Qom and in Central Iran geotectonic zone. The basement rocks of the area include volcanic units of Miocene- Pliocene (MPb), volcanic andesite units of Miocene- Pliocene (MPan), volcanic- pyroclastic units of Miocene- Pliocene (MPVP), pyroclastic units of Miocene- Pliocene and recent alluvium. The plutonic rocks of the area are granodiorite-tonalite. The intruded dykes are subdivided to andesite dykes (DY1) and dacite dyke (DY2). The main alterations are advanced argillic, alunitization, propylitic, sericitic and silicification. Gold mineralization has been occurred in andesite and dacite dykes. Au-mineralization are mostly vein, breccia and replacement type. Ore minerals include magnetite, hematite, Fe-hydro-oxides, chalcopyrite, purite and bornite which are host of Au. Geochemical data show that the average content of Au is1.98ppm. Fluid inclusions were investigated in quartz which are associated by ore minerals. These fluid inclusions are generally two-phase of fluid-rich (L + V). The results of analyzes showed that the salinity contents vary between 0.87 to 44.06% NaCl. The homogenization temperature varies between 138 and 383 ° C. The data suggest that the hydrothermal fluids which are responsible for mineralization have low to medium temperature and salinity. It is compatible to primary magmatic hydrothermal fluids which have been mixed probably to metamorphic and meteoric fluids. Mineralogical, geochemical and fluid inclusions data show that gold mineralization in the area is epithermal high sulfide type.

The Baghi-Abad skarn deposit is located south of Taft, Central Iran. Shirkuh granitoid batholite, marble and skarns are the most unit rocks in this area. The outstanding metamorphic zones are pyroxene-plagioclase skarn, melilite-fasaiite zone and finally spinel-clinopyroxene zone. The last zone of metamorphic halo is brucite marble. After this zone, marble limestone and then limestone of Taft Formation can be seen. The metamorphism and metasomatism caused by intrusion of the Shirkuh granitoid into the cretaceous carbonate rocks caused formation of calcite, wollastonite, clinopyroxene, garnet, vesuvianite, epidote, quartz and titanite. The main texture of these rocks is granoblastic, replacement and reaction, and poikiloblastic. Investigations confirm that the Baghi-Abad skarn is polygenetic in origin and evolved in two major stages, metamorphism and metasomatism (progressive and retrogressive). Prograde metamorphism characterized by anhydrous calc-silicates minerals such as wollastonite, diopside, pyroxene and garnets. The retrograde stage is revealed by the alteration of the calc-silicate minerals, the first skarn (clinopyroxene-garnet) and were formed epidote, vesuvianite. The Baghi-Abad skarn is a calcic- dolomitic and polygenic skarn and based on chemistry of clinopyroxene and garnet is comparable with Sn-W-Zn world mineralized skarns.

Brittleness which is of great significance in rock engineering properties is one of the most important properties of rock. The evaluation of brittleness indexes is a helpful method for the estimation of rock brittleness. However, there is still much uncertainty about the relation between rock brittleness and rock failures (i.e. Hydraulic fracture, Rock blasting in coal mines and tunnels). This fact can be attributed to the lack of a concept of universally accepted brittleness and brittleness index. In this paper, the relationship between rock brittleness is investigated by using the ratio of point index to porosity (PMP) in the sandstones of the Qom Formation. In addition, the available estimation methods for the rock brittleness index are summarized and their application is briefly discussed. In order to estimate of brittleness index and the ratio of point load index, 15 blocks from Latgah sandstones in northern Hamedan have been selected. Lithological characteristics, physical and mechanical properties of these sandstones have been determined. The samples have been tested under point load strength index uniaxial compressive strength (UCS), and Brazilian tensile strength experimentals. Then, the ratio of point load index to porosity (PMP) has been calculated. To achieve the desired target, the most appropriate and meaningful relationships between brittleness rock and the ratio of point load index to porosity (PMP) have been presented by the regression method. The relationships between point load index, porosity, and brittleness indexes (B1, B2, B3, B4, and BI) have been evaluated by simple regression (SR) techniques using Minitab 16 software. The statistical analyses revealed the existence of powerful correlations between the ratio point load index to porosity (PMP) with brittleness indexes (B3, B4)in the dry state and also, the powerful correlations between the ratio point load index to porosity (PMP) with brittleness indexes (B1, B2) in the saturated state.

The Kerman province is considered one of the most seismically active zones of Iran, which its frequent past earthquakes have inflicted thousands of deaths and many economic losses. Therefore, the seismic hazard zoning of this province is an essential issue. So, this research was conducted for preparing seismic hazard zoning map in Kerman Province using GIS. Several criteria such as active faults, historical and instrumental earthquakes, geomorphology, basement material, active tectonics and also their sub-criteria, which are effective in seismic hazard zoning, have been selected and evaluated. Then, data layers were weighted using AHP method by group decision making via Arc GIS and Expert choice software. Finally, the data layers were overlapped in ArcGIS based on AHP method. Different zones of the province which have been categorized of earthquake hazard, from the maximum (northeast of Kerman and Jiroft-Sabzevaran area), moderate (southeast and northwest of Kerman) to the minimum (Lut and Jazmurian) potential hazards were distinguished in the hazard zoning map. Final map was compared with past researches and seismic data which represent high accuracy of final map.

Mighan playa is the most important extraction point of sodium sulfate in Iran. The playa consists of two parts, the island in the center and the lake in the margin. Extraction of sodium sulfate on the island is associated with the formation of artificial ponds. Sodium sulfate company effluent and treated wastewater are the most important sources of surface water in Mighan playa. The effects of salinity over groundwater quality is one of the objectives in this article. The univariate and multivariate statistics such as mean comparison test, factor, cluster and discriminant analysis was used to compare saline playa with groundwater resources. In 22 samples, it was determined variables of electrical conductivity, alkalinity, total soluble solids, pH, calcium, magnesium, potassium, sodium, chlorine, sulfate and bicarbonate. It identified three water groups such as pond brine, lake brine and groundwater by differences in total soluble solids, pH, sulfate and chlorine. Multivariate analysis showed that qualitative variables are of several origins. The salinity of Mighan playa water and groundwater is related to anions and cations that originate from the gypsum and saline layers of the northern part, alkalinity and bicarbonate due to the dissolution of limestone in the southern floors of the Mighan catchment. Recent compounds are the result of groundwater and the entry of treated Arak municipal wastewater into the playa. Evaluation of the sodium to chlorine ratio and Gibbs diagram show the influence of infiltration Mighan playa saline water on the groundwater, especially in the playa margin.

A cultivation pattern in accordance with environmental conditions that reduces pollution of water and soil resources is one of the most important management strategies. This study aimed to simultaneously combine information related to soil, climate, crops and determine the potential of vulnerability and contamination of the aquifer, based on which susceptible cultivated areas (main cultivation -wheat and alfalfa) were evaluated. ArcGIS 10.3 software was used to investigate the effect of aquifer quality on cropping patterns. Climatic factors, soil parameters, and topographic characteristics were selected as effective parameters in selecting suitable cultivation sites. Nitrate content was collected in 46 wells in Shahrekord plain and averaged by kriging method, and a nitrate concentration map was obtained and combined with vulnerability map and aquifer quality area was investigated. Analytical Hierarchy Process was used to weight and finally, the layers were combined using the weighted linear combinationmethod. The results showed that areas without risk of contamination and with very low potential for contamination were 11 and 51%. Areas with low and medium to high risk of ontamination were 3 and 4%, respectively. About 25% of the aquifer area is in the high nitrate contamination range and its maximum nitrate concentration is 55 mg/l. Very high pollution (more than 75 mg/l) has not been estimated in Shahrekord plain aquifer. According to the results of this study, in terms of aquifer quality, the main part of the aquifer, about 41%, is in the safe range. 33% were classified in the low-risk group and 25% in the dangerous range. In Shahrekord plain, currently 4989 hectares are the area under irrigated wheat cultivation, which according to the results, can be increased to about 22,600 hectares. The current area under alfalfa is 3806 hectares, which according to the results, has the potential to increase the area under 28198 hectares.

In order to assess the quality of Fariman-Torbat-e-Jam groundwater resources and investigate the factors affecting the quality of groundwater, 26 groundwater samples (depth of tube wells between 70 and 260 m) were collected and analyzed for major ios, nitrate, and potentially toxic elements. pH and electrical conductivity were measured at the field. The type and facies of the samples changed from Na-HCO3 in the recharge zone to Na-Cl in the middle of the plain, and finally to Na-SO4 in the discharge zone. The results indicated the water equilibrium with carbonate minerals (calcite, dolomite, and aragonite); evaporation, dissolution and reverse ion exchange are the natural factors affecting the chemical composition of the samples. The study samples are classified as intermediate to high saline waters (class III, EC between 1300-3000 µs/cm) and are suitable for irrigation crops which can tolerate saline waters. The calculation of water quality index (WQI) revealed that the groundwater of the recharge zone (exposure of limestone rock units) is suitable for drinking usage, whereas the quality samples collected from the discharge zone (exposure of shale and evaporate rock units) is too weak. Calculation of Langelier Index indicated that the samples are not suitable for industrial applications. The Torbat-e-Jam aquifer is polluted with As, Pb (>10 µg/l), and Cd (>3 µs/cm) mainly because of natural (exposure of shales and volcanic rocks) and anthropogenic factors (agricultural practices and discharge of residential wastewaters.

There are different factors involved in water quality and it’s difficult to study all of these factors to assess water quality. Quality indexes are a powerful tool for conclusion and comparison groundwater quality. The current study investigates the integrated water quality index (IWQI) with the Kriging geostatistical technique for the Urmia plain between 2002 and 2011 over a period of ten years. Physicochemical parameters including acidity (pH), electrical conductivity (EC), total dissolved solids (TDS), and ions of calcium, magnesium, sodium, potassium, chloride and sulfate have been used to calculate the index. For different years, 63 groundwater samples were used to calculate the IWQI index and compared with other indexes such as %Na and sodium adsorption ratio (SAR). The results show that most parts of the Urmia plain are in the middle and good class in terms of IWQI classification. Also, the quality in 2004 is better than previous years and the most unsuitable quality is related to 2010. The study of spatial variations of the IWQI indicates the lower quality of the southern parts of the plain than other parts, especially the center part of the plain. As the southern parts of the plain in terms of IWQI classification is often in the middle class, and in 2010 with the decrease in the quality of the entire plain, the southern parts have also decreased to a lower quality class. The center parts of the plain are in a better condition than other parts, especially in 2004, when the quality of the middle class improved to an excellent level. The quality of the northern parts of the plain in terms of IWQI is often in the good class, so that in some years it has changed to the middle class and in 2010 to the poor class.

Argillite rocks are among the weak rocks that cause problems in engineering projects due to their swelling, high cracking, low strength. The southern Makran structural zone is located in the southeastern part of Iran, between the two faults of Makran Trust and Qasr Ghand, and includes two sub-zones of coastal Makran and outer Makran. Most of the sediments are Quartz fragments (silt size) with carbonate cement containing sub-minerals of calcite and fossil fragments, indicating a shallow and low-energy marine environment of the Neogene age. The distribution of grains is mainly silty and angular in a Carbonate cement field with a calcium carbonate content of less than 15% and in coastal Makran due to the formation of sprite calcite between 70 and 80%. In order to determine the physical and mechanical properties of southern Makran argillaceous rocks along the Chabahar-Nikshahr railway axis in this research, porosity tests, plate load test (PLT), X-ray fluorescence test (XRF) and diffraction results X-ray (XRD) are conducted. The results of XRF samples show that the major constituent oxides are SiO2, Al2O3, Fe2O3 and CaO, and the results of XRD indicate mainly silty mineralogy including: Quartz, calcite, albite, Muscovite, Clinochlore and Dolomit. The Field study in each of the sub-zones was used for rock mass classification and sampling for laboratory tests to determine geotechnical properties. According to the rock mass classifications, most sediments are in poor and very poor classifications due to tectonic conditions and high weathering. Petrological studies and determination of physical properties show that sediments located in coastal Makran have more porosity and less cement due to the young sedimentation basin and are in the category of weak rocks based on point load strength (Is50<2MPa) according to Bieniawski classification. Indirect results of the uniaxial compaction test show that the sediments have a strength of less than 20 MPa, which has a high correlation with the amount of porosity (R2 = 0.95). Also, the relationships between uniaxial compressive strength and density and Calcium carbonate are (R2 = 0.81) and (R2 = 0.89), respectively.

Hosein-Abad Jurassic slate and phyllite-hosted Zn-Pb ore deposit is located in the northern Irankuh- Ahangaran metallogenic belt. Structural investigations document the study area was structurally controlled by a northward-steeply dipping Hossein-Abad reverse fault zone with thickness of 20 meters where it cuts through the Jurassic-Cretaceous units and effected mineralization. Main mineralization of sphalerite, galena and subordinate pyrite, and minor chalcopyrite have been occurred in form of brecciation, vein-veinlet, and replacement textures as epigenetic mineralization. The main alteration minerals are quartz, siderite, calcite, dolomite, sericite, and chlorite. Geochemical investigations decipher active continental margin and anomalously enrichment of Pb and Zn for the metamorphosed Jurassic host rock. Pb, Zn, S, Cu, Ag, and As elements have the genetic relationship with the deposit. The Zn/Cd ratio in sphalerite range from 37 to 581. The Pb-Pb isotope modeling age analysis of galena suggests the remobilization of Pb from Upper Triassic-Lower Jurassic strata as most possible source. The overall ranges of homogenization temperatures and salinities of fluid inclusions range from 100 to 305 ℃ and from 10.5 to 13.3 wt. % NaCl, respectively. The Hossein-Abad reverse fault caused fault related E-W trending hanging wall anticline and foot wall-syncline, respectively. The drag folds are faded out outward of E-W trending reverse fault zone and turned to its NW-SE origin structural trend. Furthermore, the breccia- type mineralization is dominantly occurred and distributed along the Hossein-Abad reverse fault zone and clearly fade out far from fault zone.

The transition zone between the Zagros and Makran has a special place in tectonic studies in the region. The mechanism of the transition from the continental collision in the Zagros to the oceanic-continental subduction in Makran has raised some questions from the tectonics and geodynamics point of view, and these questions, in turn, has caused GPS campaigns and studies in this region and adjacent areas. In this study, the interpolation of GPS velocity vectors on a rectangular grid and strain calculation in the center of each cell was used to study the strain rate variations in this range. Noticeable spatial changes in the principal axes of the geodetic strain rate were observed in different parts of the Zagros and Makran transition zones. The anomalies observed in the calculated quantities showed significant correlations with seismicity and mechanisms of faulting on important faults in the region. In this study, a new method for mapping directional quantities utilizing a color scale with a circular pattern is also proposed for the first time. The direction of the strain rate axes in the study area was mapped by this new method and the anomalies observed were compared with the areal and maximum shear strain rate maps and interpreted based on seismological facts and observations.

The durability of rocks under variable climatic conditions is a determining factor in the use of natural rocks as building stones. Severe climate change can damage the rock structure. Therefore, to use stones as engineering and construction materials, it is necessary to evaluate their stability to different cycles of heating and cooling, wetting and drying, as well as freezing and thawing. Due to the diversity of climatic conditions in Iran, which has cold and hot, dry, and coastal areas, the freeze-thawing cycles of water is one of the most important environmental factors that can cause erosion and change the physical and mechanical properties of rocks. In the present study, the aim is to evaluate the strength changes of travertine samples as porous rock due to freezing and thawing cycles. Changes in compressive and tensile strength of the samples were determined during 10 freezing and thawing cycles. The results showed that the compressive strength of the samples was reduced by about 13.6% after freezing-thawing cycles. Also, the tensile strength of the samples has decreased by about 2.2%. Considerable reduction of compressive strength of samples in 10 cycles indicates the significant effect of freeze-thaw cycles on travertine rock.

Due to uncontrolled abstraction of groundwater and drought appearance, are the main factors in increasing deteroation of the quality of groundwater. Modeling of Dehgolan plain, using MODFLOW by using GMS software with the aim of predicting groundwater water levels was attempted. The relationship between water level potential variations and the water quality parameters (EC and TDS) was investigated. Simulations were performed for a period of 8 years time (October, 2008 to February 2015). The model was calibrated for October, 2008 to October, 2015 and validated for four months. Calibration results in both steady and non-staedy states have shown that the hydraulic conductivity decreases in the southern part of the plain. The specific discharge increases in middle and northern parts .Sensitivity analysis showed that the model shows more sensitivity to decrease in hydraulic conductivity and increase in recharge. After verifying the model and ensuring the model's ability to predict the future of the aquifer, the forecast was made for 6 years, assuming the current trend continues until 2022. The possible effects on the aquifer with Continuation of the current trend were considered in Dehgolan plain. The result showed that the decrease of water level will continue in the northern parts of the plain. The quality parameters map (EC and TDS) were evaluated during 8 years. The trend of quality changes is almost similiar with variations in water level and in the northern part of the plain. With the continuation of the trend of water level abstarctions, the amount of quality parameters (EC and TDS) will deterioted in recent years. Also, in the southern part of the plain, the quality parameters have deterioted.