نشریه زمین شناسی کاربردی پیشرفته
سال نهم شماره 32 (تابستان 1398)

In this research with application of petrofabric studies and finite strain analysis quantitative changes of strain have been evaluated in the Gachsaran rock units in the hanging wall of Ramhormoz thrust fault. Thirteen samples were selected for strain analysis in the normal section to the Fault strike along natural trench in the study area. Porphyroclasts have used as strain markers for future strain studies. The results of petrofabric studies reveal a dextral component of shear in the study area. Results of strain analysis show relative relationship between amounts of strain and distance from the fault. Three dimensional analysis of strain ellipsoid shows three axial oblate ellipsoid shape for strain ellipsoid. Kinematic vorticity analysis in the XZ principal plane of strain ellipsoid shows 0.39<Wk<0.85 and operation of both simple and pure shear components of shear strain and occurrence of strain partitioning in the study area. Percentage amounts of simple and pure shear components of strain reveal general shear with pure shear dominated component of strain.               

 In this research chalk porphyroclasts of Gachsaran Formation have been used as strain markers. Gachsaran Formation in the hanging wall of Ramhormoz fault has conserved the deformation characteristics of shear movements during the deformation history. Shear sense indicators and other strain markers such as porphyroclasts have been evaluated in this formation. These porphyroclasts have made a good fortune for quantitative strain studies in this area. In this research the strain ratios of porphyroclasts were calculated in the XZ principal plane of strain ellipsoid. With application of EllipsFit software the amounts of tectonic strain and long axis orientation of strain ellipsoid were determined using Rf/Ø and polar methods. With using the amounts of tectonic strain and orientation of the long axis of strain ellipsoid and application of (K-γ-θ-Rxz) nomogran (Fossen, 2010) the amounts of shear strain and strain ellipsoid shape factor were determined. Also with application of (Rxz-θ) nomogram (Bailey et al., 1999) the amounts of kinematic vorticity number were calculated for understanding the nature of deformation and percents amounts of pure and simple shear.                  

 The study area has been located in the Rmhormoz Anticline in the 75km NW of Ahvaz city. Structural studies show development two main joint sets that both of them are approximately parallel to the Ramhormoa main thrust fault. According to the petrofabric studies all shear sense indicators such as secondary antitaxial veins, σ type and δ type structures reveal a dextral sense of shear in the area. Using Rf/Ø and polar methods strain analysis have been made in thirteen locations of anticline based on shape factor of chalk porphyroclast. The amounts of strain tectonic in the XZ principal plane of strain ellipsoid were calculated. Also orientations of long axis of strain ellipsoid were determined in each sample. For this aim the horizontal line has used as reference line. Results show relative relationship between amounts of strain and distance from the main thrust fault. With application of (K-γ-θ-Rxz) nomogran (Fossen, 2010) the amounts of shear strain and strain ellipsoid shape factor (K) were determined. Results show 1.3<K<1.7. Therefore according to the amounts of K factor, the general shape of strain ellipsoid is three axial prolate. Kinematic vorticity (Wk) is a dimensionless measure of rotation relative to strain and characterizes the amount of shortening proportional to displacement. Wk was originally defined as an instantaneous rotation relative to the instantaneous stretching at a point (Means et al. 1980). Kinematic vorticity is measured on a scale between 0 (pure shear) and 1 (simple shear). General shear is the term used for flows between pure and simple shear (1>Wk>0) (Passchier and Trouw 2005). Pure and simple shearing components contribute equally to the instantaneous flow at Wk=0.71 (Law et al. 2004). There are several methods for determination of the kinematic vorticity number. In this research kinematic vorticity analysis was made based on Rxz-θ nomogram (Bailey et al., 1999). Rxz and θ are strain ratio in the XZ principal plane of strain ellipsoid and the angle between long axes of the strain ellipsoid related to the reference line, respectively. Results show 0.39<Wk<0.85 and operation of both component of pure shear and simple shear in the area.

 Strucrural and petrofabric studies reveal operation of both ductile and brittle deformation in the study area. According to the study of shear sense indicators, results show a main dextral sense of shear in the area. Results of strain analysis show greater amounts of Rs near the main thrust and lower amount Rs far from the main thrust fault. 3d shape of strain ellipsoid is mainly three axial prolate shape. Results of kinematic vorticity analysis show the occurrence of general shear with operation of both pure and simple shear component of deformation. The amounts of kinematic vorticity number reveals strain partitioning in the area. This strain partitioning mainly is due to oblique convergence between Iranian and Arabian plates.   
 

The Chah-Gheib laterite deposit is formed as a result of the weathering of serpantinized peridotite of the radiolarite-ophiolite Neyriz complex. occurs in the lower part of the dolomitic limestone of the Eocene Jahrum Formation which from the bottom to top includes; serpantinized peridotite transitional, limonite, hematite and laterite zones. Based on the mineralogical investigations coupled withXRD and EPMA results, the main minerals consist of hematite, goethite, quartz montmorillonite, palygorskite and olivine. . Based investigations EPMA results Gold is accompanied with silica minerals in the limonite zone. Based on the geochemical analysis (ICP-MS), the highest content of nickel is 10870 (ppm), which is related to the laterite zone and lowest one is 2066 (ppm), related to the transitional zone. There is a positive correlation coefficient between nickel and iron, which reflecting the presence of nickel in iron oxides. Based on Al2O3-Fe2O3-SiO2 diagram, the weathering in the Chah-Gheib laterite deposit ranges from strong to middle. Based on the geochemical analysis and correlation coefficient The rare earth elements show an increasing trend from serpentinite (8.97 ppm) to the laterite zones (18.41ppm. The amounts of Ce/Ce* range from 0.65 to 1.56 in the serpentinite and laterite zones, respectively. This indicates oxidized acidic conditions for the laterite zone. The Eu/Eu* increases from serpentines (0.13) to laterite zone (0.98) ref

In the last decade, the management of karst water resources has been considered because of its particular role in supplying potable water. In this regard, this research studies the hydrochemical characteristics of springs located at the Ķīno anticline. The purpose of this research is to determine the hydraulic relationship and effective factors on the chemical quality of the springs by applying the hydrochemical data and using the main component analysis and hierarchical cluster analysis methods. The results of the analysis of the main components method show that the two components have the most impact on the chemical quality of springs. The first factor consists of magnesium, bicarbonate, sodium, chlorine, Total Dissolved Solids, and electrical conductivity, which is influenced by the quality characteristics of Absard and Mourei springs. The second factor is calcium ions, sulfate, which play the most role in the chemical quality of Susan and Tangsard springs. To investigate the hydraulic connection of the springs, the hierarchical cluster analysis method was used in “Q-mode” mode. According to the results of this analysis, the data of the Ķīno anticline springs are split into two major clusters, which indicate the hydraulic connection between these springs in each cluster. The results of cluster analysis in “R-mode” mode are also validated by the Q-mode method. The Piper diagram and ion ratios were used to study the chemical processes in the springs. The results of this study showed that the S1 spring with S2 and the S3 spring with S4 have a hydraulic connection.

Non-sanitary landfill of solid municipal waste and its negative environmental impacts have made traditional methods to be replaced by appropriate and scientific methods. One of the most important phases of sanitary landfill is selecting the best spatial location to minimize environmental, social and economic impacts. The purpose of this study is to determine the proper location for solid landfills in Khorramshahr, Abadan, Shadegan and Mahshahr cities. The effective criteria have been evaluated in three categories including environmental criteria (surface waters, coastal zones, sensitive and protected areas, faults, land uses, vegetation and climatic conditions), social criteria (settlements, commercial, industrial, tourism and historical areas, railways and airports) and economic criteria (access to road and landfill, and slope). Geographic information systems (GIS), Analytical Hierarchy Process (AHP), and fuzzy logic have been used to analyze and integrate all criteria. The results showed that a large part of the area is inappropriate for landfill. In addition, the area is very sensitive to landfill environmentally and landfill site selection should be studied carefully. Finally, a map of suitable landfill sites has been prepared based on the fuzzy membership value that can be useful in municipal solid waste management in the mentioned cities.

Contamination of seven heavy metals (Cu, Pb, Zn, Fe, Al, V, Ni) and PAH compounds, and physicochemical characteristics were studied in sediments of Qarasoo River, Kermanshah. The results of contamination factor (CF), pollution load index (PLI) and enrichment factor indicated severe contamination of sediments, particularly for lead, zinc and copper in some segments of the river. Also, sampling stations near the city including oil refinery and industrial town had much higher PAH concentrations than the upstream. Based on toxic equivalency factor (TEF) and comparison of PAHs concentration with effect range low (ERL) revealed inappropriate situation of Qarasoo sediments. Among the various compounds, 3-rings PAHs are dominant with maximum concentration, same as heavy metals, in oil refinery station. Based on principal component analysis (PCA) and geochemical indices effluents of Kermanshah oil refinery are the main source of contamination of low molecular weight PAHs with petrogenic origin and copper, vanadium and nickel. In addition, organic matter and pH have also shown strong correlation with this component, confirming the role of the refinery in increasing their concentration in the Qarasoo River. Other important anthropogenic sources in the Qarasoo River include urban and industrial effluent, traffic and illegal waste disposal in the river margins.

Development of urban areas has a significant impact on the natural water cycle. Expansion of impermeable surfaces caused reduce infiltration, increase runoff volume and changes in the amount and source of aquifer recharge. The purpose of this study was to present the aquifer recharge model to determine suitable areas for urban runoff dispersal with artificial aquifer recharge approach in Urmia city. To this purpose, first groundwater recharge model was implemented. Afterwards, the potential and actual recharge map was estimated. Also, the suitable areas map for urban storm water spreading for groundwater recharge was proposed. The result shows that due to the expansion of urban areas and the increment of impermeable surfaces, the potential of direct aquifer recharge has decreased. The most aquifer recharge is through leakage from urban drinking water network, sewage wells and irrigated water returns. The actual recharge has changed according to different land use and it was between 0-28 mm/y. The greatest potential recharge was related to, bare land, open spaces, parks and agricultural land and various between 4-262 mm/y. The results indicated that in the study area, land use, impact of aeration zone and drainage net are the most important factors that affects site selection for flood spreading. Barren and agricultural land with a slop of less than 5%, areas with high thickness of aeration zone, coarse sediment and high permeable in suburban area are suitable site for groundwater artificial recharge.

In this research, non-linear geostatistical methods containing block ordinary log-kriging, indicator kriging and sequential ‎gaussian simulation as well as inverse squared distance from statistical methods (for comparison) have been employed ‎to evaluate grade and ore reserve of the Chah-bashe iron deposit, Yazd provice. To achieve this goal, first statistical ‎studies of assay data of exploratory boreholes were performed through determination of descriptive statistics, drawing ‎the histograms and cumulative probability distribution diagrams of the data. For modeling the deposit, variography ‎was also carried out through drawing various directional variograms using SGEMs software, MATLAB functions and ‎short programming in this environment. Afterward, 3-D block modeling of the deposit, determination of average grade, ‎ore reserve estimation and plotting tonnage-grade diagrams were performed using Datamine software. The results of ‎the research show that sequential gaussian simulation, indicator kriging, ordinary log-kriging, and inverse squared ‎distance‏ ‏methods have the minimum estimation variance, respectively. Although all selected methods are the most ‎accurate geostatistical methods, however the results of sequential gaussian simulation method by applying various ‎filters on the data such as using residual maps, is most highly accurate and more reliable so has more validity. ‎

Azadegan oilfield, located in Abadan Plain, is considered as one of the largest undeveloped oilfields in Iran. The carbonate Sarvak (Middle Cretaceous) and Ilam (Upper Cretaceous) reservoirs have been completely separated by the shaly Lafan Formation in this oilfield. Here, in order to investigate the connectivity between the oils of the mentioned reservoirs, organic geochemical data were integrated with the geological and reservoir pressure information. Geochemical data show that the oils of Sarvak and Ilam reservoirs have a common genetic family, originated from a marine source rock, and their geochemical characteristics are identical. Also, they have a same thermal maturity in the range of middle oil generation window. However, two distinct and unrelated oil groups were identified in these reservoirs based on the results of C7 light hydrocarbons, confirmed by the reservoirs’ pressure data. This is due to stratigraphic situation of the thin impermeable shaly Lafan Formation related to the studied reservoirs, disconnecting the hydrocarbon connectivity between them. Based on the results obtained from this study, geochemical investigation of hydrocarbon reservoirs can be appropriately used for assessment of reservoir connectivity and would improve the reservoir models which in turn plays a crucial role in reducing the risk of the field’s development and production programs.