Quaternary Journal of Iran

Abstract Production and injection of fluid may cause hydraulic fracture, shear fracture at crack levels, or re-activation of faults and existing discontinuities by reducing effective stress by changing the pore pressure and corresponding changes in the stress field. Therefore, the deformation of the earth, seismic occurred, the reactivation of discontinuities and the impermeability capacity of the rocks surrounding the reservoir-caprock are considered important factors in the implementation of projects involving the production and injection of gas in underground spaces. Successful strategy in reservoir development is inevitably of geomechanical studies and modeling of reservoir. The construction of a comprehensive geomechanical model includes the stress position, a function of depth (direction and amount), the physical properties of the reservoir rock and its formations (rock resistance and elastic modulus), pore pressure estimation, description and distribution of fractures and faults. In this paper, one-dimensional geomechanical model constructed in the studied field was described using IP (Interactive Petrophysics) software, and by analytical modeling, the possibility of reactivation of the field faults, the possibility of fractures occurring during the operations of injection and production, and the critical amount of changing pressure of injection and production to produce tensile and shear fractures, have also been studied and evaluated.

Abstract 1-Introduction
 
The Zagros Mountains range with a northwest-southeast direction covers a large part of western Iran. This range acts as a barrier against mid-latitude westerly airflows and thereby generates significant orographic rainfalls, resulting in a hospitable environment which has been home to ancient civilizations. Major variations in the westerlies can lead to significant environmental changes in this mountain range. Although previous researches have shed some light on the late Pleistocene and Holocene climatic and environmental conditions of the Zagros Mountains, our knowledge on the mechanisms controlling the paleoclimate of this historically important region is yet unknown. Most of our understanding of the Zagros paleoclimate is mainly based on the low-resolution pollen studies carried out on the poorly dated sediment cores. Because the response of the vegetation changes towards climate changes is mainly accompanied by a time-lag, it is difficult to compare the pollen records of the Zagros Mountains with the different climate records of the regions that their paleoclimate response to the climate forcing is well documented. Generating high-resolution sedimentological proxy data which immediately respond to climate variations and comparing them with the regional climate records, can enable us to reveal the response of Zagros paleoclimate to climate forcing. Here, we present a high-resolution Magnetic Susceptibility (MS) and Loss-on-Ignition (LOI) records from a sediment core collected from Hashilan Wetland located at the Central Zagros.
2-Materials and methods
 
Hashilan Wetland (34° 34 N, 46° 52 E, 1310 m a.s.l.) is a palustrine wetland located at 36 km to the northwest of the town of Kermanshah, Kermanshah Province, W Iran. According to the Köppen climate classification system (Köppen, 1931), the climate of the study area (annual rainfall: 410 mm, mean annual temperature: 15.5 °C and with 5 dry months from May to October) is defined as a Mediterranean type. The wetland is fed by a karst aquifer, called Khorrin aquifer, developed in the pure limestone of Bisotun and does not have any riverine input. The low dynamic storage volume of Khorrin aquifer makes the wetland very sensitive to variations in rainfall (Bagheri Seyedshokri et al., 2015). For example, the area of wetland shrank by 48% in 2007 due to a severe drought (Jafarbigloo et al., 2015).
In autumn 2016, a sediment core was retrieved from Hashilan Wetland. Based on 10 radiocarbon ages the 315-cm long core (85-400 cm depth) ranges from 22 to 2.2 ka BP (1 ka: 1000 years). MS and LOI analyses were carried out in this study. The down-core MS scanning was carried out in 1-cm increments using a Bartington MS2C sensor. The Organic Matter content (OM), calcium carbonate content (CaCO₃) and minerogenic content of the core was determined by analyzing 85 sediment samples.
 
3-Results and discussion
 
The results of MS measurement represent a similar trend to the results of minerogenic content of the core, indicating the role of minerogenic components in controlling the MS signal. While they display an opposite trend to the OM content results. Basically mineral particles can be transported into the wetland by water or wind transportations. If they are transported by the water running from the karst aquifer, no major magnetic mineral is expected to be transposed into the wetland, as the aquifer is developed in a nonmagnetic limestone. Hence, it can be concluded that the correspondence between MS and minerogenic content is as a result of the deposition of magnetic dust particles in the wetland during the enhanced aeolian activities. Therefore, we interpret the MS signal as dust input in our record.
Based on variations in the LOI and the MS results the core can be divided into five zones. A) 22-15.4 ka BP: This zone is characterized by minimum OM content, maximum CaCO₃ content and very low to negative MS values, indicating a lacustrine environment with no major dust input. The pollen-inferred vegetation corresponding for this period indicates the dominance of a cold, dry Artemisia-Chenopodiaceae steppe (Safaie-Rad et al., 2014). Therefore, although the climate has been drier than present, the smaller amount of precipitation has sustained for a longer time and caused a lake to form under a cold climate in which the evaporation rate was substantially suppressed. B) 15.4-10.5 ka BP: A sharp change in the lithology from marl to gyttja indicates an environmental change from lacustrine to palustrine at 15.4 ka BP onward. This change most likely has occurred due to a notable increase in the temperature which is in agreement with a concurrent rise of the temperature inferred from changes in the diatom assemblages of the nearby Lake Zeribar (Wasylikowa et al., 2006). The increase in the MS values reflects higher dust input in this zone than the underlying zone. C) 10.5-7.8 ka BP: This zone is characterized by maximum minerogenic content and MS values vs. very low OM content (minimum in the Holocene section of the record), indicating intensified dust input into the wetland through the enhanced aeolian activities. The period between 9 and 7.8 ka BP exhibits the peak of dust input, which is in accordance with the desiccation of the wetland and consequently decay of the pollen grains in this time (Safaie-Rad et al., 2014). By contrast, a short-term interval at around 9.2 ka BP, represents an abrupt decline in the dust input probably due to the alleviation of aridity. D) 7.8-6 ka BP: A decrease in the MS signal and minerogenic content reflects a reduction in dust input, suggesting a decrease in aridity in compare to the previous zone. E) 6-2.2 ka BP: This zone is characterized by the Maximum OM content and decline in the MS values and minerogenic content, suggesting a wetting in the climate. This is supported by the expansion of the Zagros oak woodlands at around 6 ka BP (van Zeist and Bottema, 1977; Safaie-rad et al., 2014).
These variations in the Holocene climate of the Zagros Mountains are completely opposite to the variations in the Indian Summer Monsoon (ISM) intensity recorded in the speleothem records from Oman and Yemen (Fleitmann et al., 2007), indicating the role of insolation changes in controlling the climate of Zagros Mountains.
   
4- Conclusion
 
In this study we generated the first high-resolution paleoclimate record for the Zagros mountains by measuring MS of a sediment core retrieved from Hashilan Wetland and compared our results with the regional paleoclimate records. Following conclusions can be derived from our results:
 

Hashilan has been a lacustrine environment from 22 ka BP (the bottom of our record) until 15.4 ka BP and changed to a palustrine environment from 15.4 ka BP onwards.
The MS signal of Hashilan wetland, as the indicator of dust input, along with the LOI results revealed an out-of-phase relationship between the moisture evolution in the Zagros Mountains and the ISM domain during the Holocene.
During the early Holocene (10.5-7.8 ka BP) the Zagros Mountains has experienced a dry climate characterized by enhanced aeolian activities, as reflected in high MS values particularly between 9 and 7.8 ka BP. It is most probably as a result of the longer establishment of the STHPs over the Zagros Mountains which protracts dry summer season.
After 7.8 ka BP, the abrupt decrease in the MS values vs. increase in the OM content which culminates at 7.5 BP, suggests an alleviation in aridity. In the period between 7 and 6 ka BP the aridity increases again but does not reach to its intensity in the early Holocene.
During the Mid-late Holocene (6-2.2 ka BP [top of our record]), low dust input and high OM content reflect a wetter climate.

Abstract Mirak (Semnan, Iran) is a Paleolithic site located in a dry floodplain near the northern edge of the Iranian Central Desert. The pedo-sedimentary successions of Mirak 8 are deposited from late Pleistocene to Late Holocene,. The chronological framework was established using optically stimulated luminescence (OSL) dating. The oldest studied units dating back to ~50 ± 3.0 ka. Within this stratigraphy, two distinct depositional environments are recognizable: Sequence I = alluvial floodplain deposits and Sequence II = calcareous aeolian deposits. The alluvial succession is represented by alternating horizons of poorly pedogenized bodies of loam, intercalated by splay sand interbeddings. The prehistorical remains occur exclusively at distinct limits and it is presumable that some prehistorical layers of Mirak are palimpsests resulted from repeated occupations. After ~1.2 ± 0.2 ka  an at least 3 ka long sedimentary hiatus cuts the sedimentary log of Mirak 8 and about 2m of aeolian assemblages take place over the discontinuity. This shift was clearly reflected in the laboratorial results. Results from XRD, FTIR, SEM and optical microscopy analyses, show very minor differences in mineralogy for the entire record regardless of the type of depositional regime and this we suggests a local and most probably polygenetic source for the deposits under study. Subsequent to deposition, both alluvial and aeolian accumulations were subjected to different extents of pedogenesis and thus developed pedogenic features characteristic of Entisols and calcareous, gypsiferous Aridisols (Bk, By). Varying iron content and different oxygenizing conditions between the two sequences are presumably relatable to higher ground water level and Fe-reducing conditions especially for the units deposited prior to ~28 ± 2 ka BP (OSL) and generally adverse conditions for the Holocene units.

Abstract During a period of several thousand years, from the end of the Pleistocene to the beginning of the Holocene, human societies were able to change their way of life, which was based on hunting and food gathering, to agriculture and a succession. This remarkable transformation, which is also referred to as the process of neolithic/neolithic, is one of the important topics of prehistoric archeology. In relation to the geographical extent of the occurrence of this important development, in general, there is a general agreement about Southwest Asia among researchers. Recent researches in the Zagros highlands and its foothills have led to the discovery of very important evidence related to the Neolithic process and have once again turned the attention of researchers to the eastern parts of the fertility crescent. New archaeological researches in Kohgiloye area, as a part of the southern highlands of Zagros, and the identification of a significant number of early Holocene settlements from the high potential of this area to study the Neolithic process in this part of the Iranian plateau. It tells a story. In the investigations carried out in the Kohgiluyeh area, 16 sites of early settlements of the Holocene period have been identified. From the morphological point of view, these settlements are classified into four groups of hills (5 hills), open areas (8 areas), rock shelters (2 shelters), and one cave. they become In general, the settlement and livelihood patterns of these areas are influenced by several factors of plains, rivers, mountains, and gorges, which shows that the societies of this period have benefited from all the environmental potentials of this area.

Abstract Surface and groundwater resources such as Arnaveh karstic spring and Shirin Dareh reservoir are the main sources of drinking water and agricultural activity in the North Khorasan province, northeast of Iran. The main agents of this study are to evaluate the origin, hydrochemical and isotope characteristics of water resources and also suitability of the Shirin dareh reservoir water for drinking and agriculture usages. Water samples were collected in October 2017 from Arnaveh Spring, Shirin dareh River and dam reservoir to measure the EC, TDS, major ions concentrations and stable isotopes (δ¹⁸O, δ²H) values. Furthermore, the two rain stations were selected for isotope sampling from rain waters and determining the Shirin dareh isotope Meteoric Water Line. According to hydrochemical characteristics, Ca-Mg-SO₄ and Ca-Mg-HCO₃ are the dominance waters type in the area. The average electrical conductivity is about 900 µS/cm. The δ²H = 7.14 δ¹⁸O + 5.67 (R= 0.96) equation is proposed as LMWL of the study area based on the precipitation samples. Its slope and intercept are lower than the GMWL due to secondary evaporation from rain drops in low humidity condition. The isotopic results suggested that the Arnaveh spring and surface waters (river) are originated from modern atmosphere precipitation. Due to evaporation, isotope composition is more enriched in dam reservoir than in river samples and has a slight deviation from the local meteoric water line. The quality indexes confirm that these water resources is suitable for Irrigation and drinking usages.
 
1-Introduction:
Shirin Dareh Basin is located in northeast of Iran. Shirin Dareh dam is the main source of drinking water and agricultural activity in the Northern Khorasan region. The geochemical investigation provides more information about ground and surface waters mineralization and the processes controlling the deterioration of water quality. Water quality in dams depends on the geological characteristics of the catchment area, the quantity and quality of water entering the reservoirs of dams, the amount of precipitation and the amount of agricultural and industrial activities. Sustainable management of the water resources needs a comprehensive understanding of the sources of water and spatial variability of hydrochemical and isotope characteristics. Water isotopes are commonly used for determining the sources of surface and groundwaters. The aim of this study was to investigate the spatial variations of water quality in the river and Lake of Shirin Dareh dam, as well as the origin and chemical evolution of water resources with different methods of hydrogeochemical and isotopic methods. This type of study was carried out for the first time in this area, and in addition, the local precipitation line of the isotopic rainfall in the Shirin Dareh area was also measured and plotted.
2-Materials and methods:
Samples were collected for one period (October 2017) from Arnaveh spring, Shirin Dare River and dam reservoir. Electrical conductivity, total dissolved solids, major ions (Ca, Mg, Na, K, HCO₃, SO₄, Cl, NO₃) and stable isotope (¹⁸O,²H) were analyzed. Furthermore, isotope values of the precipitation samples in two rain gauge stations in the study area were also measured to determine the isotope meteoric water line. Hydrochemical diagrams, such Piper, Schoeller, Chadeha, different ions ratio, Gibbs and Saturation Index (SI) were used to evaluate the hydrogeochemical characteristics. Six factors such as residual sodium carbonate (RSC), magnesium adsorption ratio (MAR), sodium percentage (%Na), sodium adsorption ratio (SAR), Permeability Index (PI), and water quality index (WQI) were calculated to evaluate the water quality within the research area for irrigation and drinking activities.
3-Results and discussion:
According to the Piper and Chadeha diagram, Ca-Mg-SO₄ and Ca-Mg-HCO₃ are dominance type of water. Gibbs plot showed that all of the samples fall in the rock dominance. The hydrochemistry results and different ions diagrams indicated that the most important factors controlling the chemistry of water included carbonate, anhydrite and gypsum dissolution and to a lesser ion exchange process. The most of water samples are saturated or oversaturated with calcite, dolomite, gypsum and anhydrite.  Dissolution of halite is negligible; therefore, SI of halite is under saturated in the study area. Arnaveh karstic spring with lower EC value has the effective role in improvement of water quality of the Shirin Dare River. The average of electrical conductivity is about 900 µS/cm. All river and dam samples are plotted between the mixing line of the two samples of upstream and Arnaveh spring; indicate that the water quality of the river after mixing with the spring has improved and the concentration of ions has decreased too.  
Many factors such as evaporation and water-rock interaction can control the relative abundance of an isotope in surface water compared to the precipitation. According to the isotope composition of the precipitation samples, The LMWL equation is computed as δ²H= 7.14 δ¹⁸O + 5.67 (R= 0.96). Its slope and intercept due to secondary evaporation from rain drops in low humidity condition are lower than the GMWL. The isotopic results suggested that the Arnaveh spring and surface waters (river) are originated from modern atmosphere precipitation. Due to evaporation, isotope composition is enricher in dam reservoir than in the river samples. The isotopes stability signatures show that river samples are non-evaporated and controlled by the dissolution, whilst reservoir samples are more ¹⁸O and ²H-enriched due to the evaporation from reservoir surface. The quality indexes confirm that these water resources is suitable for Irrigation and drinking.
 
4- Conclusion
To summarize the geochemical and isotopic techniques and water quality indexes were used to evaluate the origin and chemical evolution of surface and groundwaters in the study area. The groundwater samples from Arnaveh spring is mainly affected by natural factors and processes such as lithology, evaporation and water-rock interaction. The isotope composition (¹⁸O and deuterium) indicates the importance of evaporation in dam reservoir, and recharge with modern rainfall. The water quality in the study area seems to be good for different usages.

Abstract 1-Interoduction:
Air pollution has been considered as one of the global challenges. According to world health organization (WHO), dust particles are the 5th most dangerous cause of death 4.2 million in the world. According to the world meteorological organization (WMO), when the wind speed increases more than 15 m/s and the visibility decreases because of dust particles less than 1 km, it is called a dust storm. Considering the potential impact of dusts around the city of Qom, it is possible to influence the impact of dust storms on the extent of these centers and their contribution to the air quality of the city of Qom in the aftermath of a storm of dust.
The dust storms that affect Qom are originated from two local and transitional emission sources. The main objectives of this study were identification of the main quaternary geological structures as emission sources of dust storms, study dust storms paths and determine the important emission sources that are affect Qom air quality.
2-Material and methods:
Initially, dust storms were detected using dust codes and verification of MODIS images during the period 2008 to 2017. Remote sensing is a suitable method for detecting dustborne events and has recently been successfully used to understand the location of dust sources.
 
The position of geological formations at the site of the focal points indicates that the bed of most of the focal points is from quaternary deposits. The Quaternary geological period is the fourth and final period of geology, and most of the constituent parts of these centers, including the ancient coniferous terraces and clay alluvial tundra, are prone to dust production. This study were trajectory using HYSPLIT model and orientation index (windrose, dust rose and CPF). In order to investigate the wind condition as one of the most important factors in dust storms, windrose and dust rose were used using WRPLOT software. One of the common ways to identify the geographic direction of dust sources is the CPF function. The CPF examines the potential of any direction in the transfer of pollutants, especially particulate matter released from a source in which the wind is greater than the specified threshold. The HYSPLIT model is one of the most practical methods for determining the duct movement, dispersion and dip galvanizing simulationThe model of the propagation algorithm was identified for each occurrence and was investigated at three altitudes of 10, 500 and 1000 m in backward for 24 hours for local Events and 72 hours for transitional Events.
3-Results and discussion:
Out of 531 identified events, after verification by dust codes and MODIS images, 400 events were detected in Qom between 2008 and 2017 years about 84 percent of the incidents occurred in the spring and summer. The results of windrose and dust rose indicate that east and west directions have the highest wind direction in Qom, which are differents in different seasons, and the results of windrose are more similar to the seasonal results of summer and spring, the occurrence of most events in two seasons spring and Summer shows. Seasonal CPF results with slightly different windrose and dust rose results, show the northwest and east directions in the spring and summer, and northwest in the autumn and winter seasons. Due Because of the CPF shows the potential for dust production and most of the events occurred in the spring and summer season, the results of the windrose spring and summer and dust rose were similar and confirm the occurrence of this dust numbers in the two seasons of spring and summer In these directions. The results of HYSPLIT At three altitudes of 10, 500 and 1000 meters in the period from 2008 to 2017 in Qom Due Because of the two altitudes of 1000 and 500 meters are far away from the phenomena and topographic changes of the Earth, they have little effect on the dusts. Dust routing results at 10 m elevation were studied. The results of trajectiries the HYSPLIT model at 10 m elevation in the study period in Qom show that the most important directions of dust entering the city of Qom, Like the results of wind rose, dust rose and CPF, it is east, southeast, west, and southwest, who There are many events in the east and south-east of the west and southwest, and From these directions, there is no significant dusting in the southwest direction around the city of Qom, and in other directions there are many dusty centers. Investigating the frequency and direction of the dust storm trajectory occurring in Qom during the studied period shows that the most important centers dust that affect the air quality of Qom city, where the threat of more events has passed, Respectively, the centers of numbers 4, 10, 11 and 2 are located among these centers, centers numbers 4, 10 and 11 in the direction of east and south-east of the city of QomThe center number 2 is located west of the city of Qom, and this direction was also Is important recognized by the results of wind rose, dust rose and CPF. Also, the results of the HYSPLIT model trajectory for transitional dusts Which has influenced the city of Qom during the studied period, shows that most of these dusts from the country are than Iraq, then Syria and Saudi Arabia.
4-Conclusion
There are several dusts centers around the city of Qom. Among these centers, the center of number 4 (the distance between salt lake and Houz-e-Sultan), located east of Qom, is due to the close distance, high area, the genus of the formation and, most importantly, the abundance The passage of events from this center, which includes the largest number, and centers of numbers 10, 11 and 2 too After the center of number 4, is the most important and most influential source of dust on the city of Qom relative to other centers.
 

Abstract Introduction
This paper is taken into consideration to provide earthquake acceleration maps in Saveh area based on seismicity. Ipak fault with the length of 100 km, the eastern-western bending direction, is considered as the most effective earthquake factor in this area. This fault is the cause of the horrific event of the 1962 Bouin Zahra with a magnitude 7.2. The faults of the Indes, Baghestan, Eshtehard, Koshk e Nosrat are other region faults which are in the active class. The 1177
earthquake, with a magnitude 7.2, in the east of the study area, was considered as the largest historical event. The earthquake of 1119 AD, with a magnitude of 6.5, is also the second largest earthquake of this zone from Iran. The 1962 earthquake with magnitude 7.2, as the largest device event in this area, has occurred in related to the Ipak fault activity. The second major device earthquake in the area is associated to earthquake 2017 Malard with magnitude 5.2.
Materials and methods
The way forward of this study, entails seismic springs, identification and estimation of seismic parameters and involvement of historical earthquakes in analyses. Eventually, analyses are conducted in the EZ-Frisk software environment, by assigning these parameters to seismic springs. The probabilistic method was used in order to estimate the maximum values of the ground-level movement parameters. They were used the new generation equations of the calculation to determine the maximum amount of ground motion parameters. In addition, in order to calculate the acceleration of the earthquake, the lattice points with appropriate distribution (intervals of 5 * 5 km) and more than 645 points, were made the definition and calculation of earthquake acceleration for each of these points.
Results and discussion
The results of these studies were presented in the form of horizontal acceleration maps for a period of close to zero seconds (PGA). Regarding these maps, the maximum acceleration is approximately 0.94g and is related to the earthquake with a return period of 2475 years. For a return period of 975 years, the maximum acceleration values are nearly 0.69g. In the return period of 475 years, the maximum earthquake acceleration is about 0.49g.
Conclusion
Comparing the results of this study to Jamali and Tavakoli-zadeh (1387) studies is comparable for the period of returns of 475 and 2475 years. Accordingly, the maximum acceleration seismic in the study area, for the aforementioned return periods are 0.41g and 0.57g respectively. Results can be different due to the software weaknesses in three-dimensional modeling of springs, the equations of old declining with limited functionality and the modeling of seismic springs. The maximum earthquake acceleration in these studies, based on the return periods, is 0.35g and 0.50g, respectively. According to this, by comparing the results of the return period of 475, the estimated numbers are in consistent with the data of this article. This issue is due to the software being identical, input data, and diminished equations of relatively new.