مجله پژوهش های دانش زمین
پیاپی 52 (زمستان 1401)

The study variability of precipitation change in Iran is more important than other climatic variables. Precipitation changes can control the length of dry spells in arid and semi-arid such as Iran. Extraction and analysis of precipitation, is a good criterion for understanding the behavioral mechanism of Dry Spells. Recognition the change in length of Dry Spells such as the frequency of events, the length of periods, its severity and continuity is very important in environmental planning. Therefore, study of the occurrence and sequence of dry Spells is great importance in climate change studies.

for identify and describe the precipitation, the firt step, provided database matrices of precipitation data in a period of 30 years from (since1990-2020) for 8 precipitation stations in the province area. In second step for evaluate the behavioral similarity of station data and assignment of all stations to a homogeneity criterion, was performed Homogeneity test (HT). by used and the help of programming and coding in MATLAB and R software, is calculated on a seasonal and monthly scale with a threshold of 5 mm to be the basis for extracting and zoning dry Spells in ArcGIS software. The behavior of dry Spells with different continuities was analyzed and zoned using the second-order Markov statistical chain. In the last step for predict the behavior of dry spells in the middle decade (2050) by referring to the scenarios of HADGEM2-ES model related to the fifth report of the intergovernmental panel of climate change (IPCC-IR5), to downscalling and reproduce data in the statistical environment of SDSM software for all stations. In the final step, the seasonal behavior and the area of dry periods in the future horizon were plotted. How to do each step will be described in the research sections.

 In order to determine the degree of homogeneity and to determine the stations that are in the spatial range τ_4 and τ_3, the Husking torque homogeneity test was performed to determine the data and the outlying and heterogeneous stations. According to the definition of stations, the test component H1 for Lcv, H2 for the combination of Lcv and Lskew, and finally H3 for the combination of Lkurt and Lskew, where the statistics inconsistency is less than 1, are considered homogeneous stations. Stations with more than one statistic were excluded from the study and other stages of the research. Lodab and Abdehgah stations had such conditions. Mean and output of all stations for statistics at level /.43. Adjusted (average of H1 to H3 statistics). In fact, this method minimizes inter-station variations in linear torque to increase the reliability of the network data usage. In general, the study of wet and dry monthly events showed that throughout the province, dry periods with a duration of 30 days or more have the highest probability of occurrence and the shortest return period. Based on the output of monthly emission scenarios of climate change models, the length of dry spells in the province in the cold seasons of the year with an average (29%) has a more significant increase than the warm periods of the year with an average (19%). It can be said that in tropical and arid regions the return period with short-term continuities and in mountainous and cold northern regions, the return period with long-term continuities is more dominant. Wetlands of the province are more vulnerable to drought and climate change and from west to east and from south to north increases the area of dry areas in the province. In other words, the border of arid regions shifts to the east and north.

The change in the length of dry periods in the arid and super-arid zones of the south and west of the province, especially cities such as Gachsaran, Imamzadeh Jafar and Dehdasht, which have polluting industries such as petrochemical and oil industry, is a serious warning for the dominant industries such as water resources, agriculture and tourism. Is. Challenges arising from the drying up of water resources such as Hur al-Azim wetland and declining discharges of rivers and dams in the neighborhood in the southern regions of the province, the challenges arising from climate change such as increasing the length of dry spells intensify. It’s necessary for planning and adaptation to climate change and management of available water resources in all areas of the province, especially in the northern and eastern area, where the possibility of long-term dry periods is high and inevitable.

Gully erosion is a destructive form of water erosion that cuse lost a significant amount of valuable soil and its control requires understanding the relationships between the characteristics that affect this phenomenon. The purpose of this study was determining the most effective variables on the gully volume and length.
Gullied area identifed with Google earth in the Jahan Abad, Buin zahra (Qazvin province), 33 gullies were selected, recorded by GPS and their morphologic characteristics including length, width and depth were measured. Surface soil samples were taken from headcut and were analyzed for texture, EC, pH, organic matter and some Anions and Cations. Indices related to the form of watershed were extracted from the digital elevation model which derived from UAV image processing. Correlation between factors, PCA and multivariate regression were performed to determine important and effective factors on gullies volume and length in MINITAB.
 Results indicated that gullies have vertical headcuts, trapezoidal cross-sections and linear general plan. The average depth of headcuts, depth at 50% of the gully length and the average gully length were 0.35, 0.47 and 13.46 m, respectively. Soil texture was loam and average soil texture components including sand, silt and clay were 38, 38 and 24%, respectively. The mean EC and pH of the samples was 11.2 dSm-1 and 8.7 respectively. Linear correlation between the total volume of soil volume and length and other characteristics showed that silt have significant correlation coefficients at 1% percent level 0.465 and 0.510, respectively. PCA with soil characteristics and watershed characteristics showed that the first and second components are close to 41% and 8 other dimensions with egen value more than one, with 84.2% are responsible for changes. Chlorine, electrical conductivity and sodium with negative effect and aggregate stability, canopy and amount of sand with positive charge in the first component have the most weight, while in the second component, sand, canopy and amount of gravel with positive effect and TNV, organic matter and saturation percentage play a more important role. The results of multivariate regression also showed that carbonate, magnesium, potassium, organic matter, saturation percentage, amount of sand, slope of gully floor, slope of inlet waterway to headcut, litter, basin primeter, respectively, effective properties on soil loss by gully in the region. Form coefficient had the greatest effect on soil loss, respectively, and were included in the prediction equation of soil loss with R2 of 0.837. Stepwise regression with the dependent variable of gully length showed that the relationship has R2 of 72.98% and is significant at the percentage level.
Factors affecting the length of the gully included the percentage of saturation, the amount of sand, specific gravity, the slope of the gully floor, the slope of the waterway entering the upstream, geravel, basin area and slope.

There is strong feedback between river channel dynamics, floodplain and coastal plain development. Rivers are active phenomena that are constantly changing their bed and banks, and this causes the course of the river to undergo fundamental changes over time. Kalibarchai river is one of the most important rivers in Arasbaran region, which is the main drainage of Kalibarchai basin to the permanent Aras river. This study was conducted to determine the quantitative changes of land use on river dynamics along the Kleibarchay River in East Azerbaijan for a period of 20 years (2000-2020).

The configuration and survey of the Kaleybarchay River Canal for 2000, 2010 and 2020 have been evaluated using Landsat satellite imagery, Landsat 7ETM Sensors images and Landsat8 satellite OLI / TIRS images. In this study, for reconstruction and separation, various indicators such as: Normalized Water Difference Index (NDWI) and Normalized Water Difference Correction Index (MNDWI) and also to detect and determine the type of uses, through the supervised Maximum Likelihood classification method have been used. Google Earth imagery was used to evaluate the results of the indicators used. Arc GIS software was used to create the database, spatial-spatial analysis and ENVI software was used to process satellite images. Atmospheric corrections were performed to eliminate the effects of scattering and absorption of electromagnetic waves in the range of visible and infrared waves. In order to make atmospheric corrections, the first step of calculating the amount of radiance was calculated, and from the amount of radiance, we reached the desired atmospheric correction process. Finally, atmospheric correction was performed on the images by FLAASH method.

Lateral dynamics changes of the Kaleybarchay River canal during the last 20 years were studied using the transect method and the curvature coefficient and migration rate of the canal. The highest average of lateral duct displacement between 2000 and 2020 with the value of /51, is related to transect number 1 and the lowest amount of duct displacement is related to transect number15 with the value of /10. Over a period of 20 years, despite the creation of shortcuts and lateral migration, the mean values ​​of the sinusoidal and radius of curvature of the Kaleybarchay River canal have not changed significantly.

This shows that the river is in dynamic equilibrium and has not changed much in the last 20 years. In land use analysis, the most changes have occurred in pastures and barren lands, in other words, as we go from 2000 to 2020, the amount of pasture lands has increased and the amount of barren lands and rocky outcrops has decreased. In the meantime, it is interesting that during 20 years, the amount of forests and forest lands in the study area has increased. Its area has increased from 43.70 hectares in 2020 to 180.32 hectares in 2020.

Temperature anomaly means deviating from the reference value or the long-term mean. A positive anomaly indicates that the observed temperature is warmer than the reference temperature. Temperature anomalies, especially in the cold period of the year, may have devastating effects on agricultural products, loss of plant and animal life, ecology, facilities and structures, food security, and etc. Rising ground temperature will increase evapotranspiration, decrease the level and depth of snow, change crop phenology and finally a serious threat to food security in the country. Therefore, studying temperature anomalies in different ways is very important.

A) In this study, temperature data were collected for 45 units during the statistical period of 1980 to 2018. For selecting the modules, in addition to considering the different climatic regions of Iran, an attempt was made to select one module from each province.B) Using the open analysis database, the modified GFDL-NOAA-ESM2M model was conducted to study temperature changes in Iran during the statistical period of 1975 to 2005.C) In this research, the MOD11C3 product of MODIS satellite data was used.D) In order to evaluate the trend of surface temperature and its anomalies in Iran, non-parametric Mann-Kendall test was used.E) In order to evaluate the analyzed the obtained data from the SM2M-GFDL-NOAA model and the provided satellite data, different methods such as the R- Square, mean square error and mean square error data were used.

The main focus of the maximum temperature in this month is in the northwestern regions of Iran. The coastal provinces of the Persian Gulf and the Sea of   Oman are among the regions with the highest surface temperatures. By passing from low latitudes to high latitudes, the surface temperature of the earth has gradually decreased and the minimum temperature has appeared in the northwestern parts. According to satellite data, the maximum anomaly was observed in the northwestern, western and southwestern regions, as well as the highlands of Khorasan Razavi and North Khorasan. Minimal anomalies in the northern strip from Ardabil province in the northeastern regions, Kerman province, South Khorasan and Sistan and Baluchestan. The ESM2M-GFDL-NOAA model had the best performance compared to satellite imagery and was therefore used to find the model trend and change gradients. The slope of the trend in the interior places of the country, specially around the Kavir desert and Jazmourian hole is estimated to be 0.1 degrees Celsius. This means that the surface temperature in January during the period during the year increases by 0.1 per year in these areas. In the highlands of South Khorasan and the northern parts of Fars province, the slope of the trend is 0.03 to 0.01 degrees Celsius. This trend is decreasing and the ground temperature decreases between the mentioned values   every year. The northern regions of Khorasan Razavi, the eastern regions of Sistan and Baluchestan and the northern regions of the Lut plain are among the regions in which the trend slope increased in February during the statistical period 1975 to 2005 and the LST increased between 0.17 and 0.19 degrees Celsius per year.

The results of the surface temperature assessment using treaa MODIS data during the statistical period (2001 to 2018) indicate that the surface temperature is affected by topography and latitude, so that during the period which the minimum surface temperature of the day at the Caspian coast and in The Alborz mountain range and the northwestern regions of the country were observed.The pattern of the earth's surface temperature prove that as we go from north to south and from west to east, the earth's temperature has increased.The results of night surface temperature anomaly monitoring showed; In the cold months of December, January and February, the maximum surface temperature anomalies were observed overnight in the Alborz highlands and around the western mountains of the country. In March, October and November, the Caspian coast had the least anomalies. In the warm months of July to September, the interior and eastern regions of Iran showed the least surface temperature anomalies. In June Southeastern regions of Iran near Sistan and Baluchestan province had a significant upward trend in the level of 5% confidence and other regions of Iran showed different trends in different months. In June Southeastern regions of Iran near Sistan and Baluchestan province had a significant upward trend in the level of 5% confidence and other regions of Iran showed different trends in different months. Ground surface temperature trend slope based on non-parametric Sense test of simulated data of ESM2M-GFDL-NOAA model, where the trend slope is different and there is a positive and negative trend slope in different seasonal situations.

In many countries, baseline concentrations of heavy metals in soil have been studied; this information is used as a reference to assess soil quality status (Karim et al, 2015). Soil concentrations of elements in the soil are a function of the mineralogical composition of the parent material and weathering processes affecting soil formation as well as properties such as particle size, clay content and soil organic matter (Azimzadeh and Khademi, 2013). As a result, the natural concentration of elements in soils is widely variable and the use of baseline (threshold concentration of heavy metals) of other countries and the global average to identify the extent and risks of heavy metal pollution in soils of areas where environmental boundaries are not defined is incorrect (Ghanavati et al, 2019; Nazarpour, 2018). Fractal geometry studies natural phenomena and complex and irregular objects with mathematical relations. One of the major applications of fractal geometry is in estimating the thresholds and thus separating the abnormal community from the field based on their fractal dimension differences (Nazarpour et al, 2015). In this research, this model has been used to determine the baseline concentration of heavy metals.
In this study, in order to evaluate the background concentration of some heavy metals in surface soils of Khuzestan province. The sampling method was that first, using random sampling distribution in GIS, the proposed neighborhoods in the study area were determined. The points were selected to cover the entire study area. Samples were taken in combination (mixture of 3 samples together, with a distance of 50 to 100 m) from a depth of zero to 20 cm from the soil surface and with an approximate weight of 500 g and a total of 87 samples were prepared. The samples were dried in room air for 48 hours, then crushed and passed through a 200 mesh polyethylene sieve. After preparing the samples, heavy metals were measured by induction coupled plasma spectroscopy (ICP-OES) of the model device (Model Varian735).
According to the results, the studied heavy metals show a wide range of concentrations. The concentrations of Ni, Co and Pb were in the range between: 38-320, 5-16 and 5-41 mg/kg. The lowest and highest mean concentrations of the studied metals were related to Pb and Ni, 9.09 and 66.34 mg/kg, respectively. High concentrations of heavy metals indicate the impact of human activities in the region (Sadeghdoust et al, 2020). In this study, after sorting the data from high to low and determining the frequency of each concentration, logarithmic plots of cumulative frequency of metal concentration versus area were drawn. By obtaining the breaking points, the threshold of each metal was determined for the concentration-area method. Baseline values for Co, Ni and Pb were 6.93, 47.59 and 6.26 mg/kg, respectively. The results showed that the application of fractal methods in separating the amount of baseline from other geochemical populations is very appropriate.
Geochemical maps prepared by fractal method of concentration-area have a very good adaptation to the conditions of the region in terms of natural conditions of the region, land use and especially the effect of industrial units on the concentration and abundance of heavy metals and heavy metal pollution in the region. The results show the effect of anthropogenic factors on the concentration of metals. In general, the results showed that different factors, including human and natural factors together, are always effective in the distribution and concentration of heavy metals. Therefore, in order to maintain the balance of the ecosystem, human health, identify adverse effects on the environment and its proper management, it is necessary to determine the concentration of the field or the limits of environmental safety according to climatic conditions, region and soil properties.

Some researchers supposed that investigating the formation of serpentineites can have important applications for understanding the large-scale geodynamics of that earth (Hattori and Guillot, 2003; Hilairet et al, 2007). Serpentineization occurs in a wide range of temperatures and pressures, low temperature serpentinite of alpine type ultramafic rocks occurs due to the penetration of atmospheric waters or from the infiltration of saline waters derived from sediments. This often refers to retrograde serpentineization. In contrast, progressive serpentineization occurs in many metamorphic processes during burial and warming of ultramafic rocks, which includes minimum water, during this process from the reaction of chrysotyl, antigorite and brucite, or antigorite reaction with brucite, forsterite + water were formed (Klein et al, 2014; Evans et al, 2013). The formation of anteatgorite may also occur from the reaction of chrysotyl/lyzardite with talc (Murzin et al, 2013; Lacinska et al, 2016).
After sampling and evaluation of microscopic sections, samples performed by X-ray micro-analyzer by Cansaran Binalood Company. With the aim of studying the whole rock geochemistry, 11 representative samples sent to the Zarazma Company of Tehran and ICP-MS analysis made for rare earth elements and transitional elements and XRF to obtain the major oxide elements.
The remaining olivines were ferro-hortonolite, spinels were chromite, clinopyroxenes were hedenbergite and orthopyroxenes left by serpentineization were ferrosilite. The geochemistry of these rocks is similar to the mantle wedge serpentinites studied along the Neo-Tethys. For example, with Voltri Massive serpentineites in the Italian Alps (Cannao, 2016) or with average subducted serpentinites (Deschamps et al, 2013). The serpentineization of these rocks start from the ocean floor, where the penetration of water in the fractures of the young oceanic crust and in hydrothermal veins, and spread with flat subduction in low temperature metamorphic facies. Since the main serpentine phase in them identified by XRD was chrysotyl, which is associated with the main mineral magnetite, so it is clear that their depth of subduction was low.
The various microstructures identified in these rocks are mesh, sieve, augen, strip, hourly glass, etc. and the effects of elastic (microfolds and kinks) and brittle alteration. The growth of lyzardite plates in the margins of low crystallized mass nuclei is irregular and the increase of serpentine veins and strong deformation reduces the resistance of serpentinites to shear and stress. With precision on the contents, ratios and diagrams, Gysian serpentineites evaluated as subducted type. The content of FME in these rocks is very high and is a sign of re-fertility resulting from the interaction of rock/fluid during subduction stages, which distinguishes it well from other types. In the absence of antigorites in these rocks, the depth at which Gysian serpentineites created was less than 50km. According to the above, Gysian serpentineites are subducted type in the northwestern part of Iran. Along the main Neo-Tethys sutur in Iran, other subduction serpentinites have been reported in Iraq and northwestern Anatolia in Turkey and Gysian serpentinites could be assumed a part of it.

In the Kopet Dagh sedimentary Basin in north east of Iran a full record of Mesozoic and Cenozoic strata is present. In the Kopet Dagh Basin, Neyzar and Kalat formations belongs to the upper Cretaceous strata. Neyzar Formation is located on the Ab-Talkh Formation and is overlain by the Kalat Formation and mainly consists of fine to medium grain sandstone in the lower part and limy shale and marl at the upper part of the section (Darvishzadeh, 1370). The main aim of the present study are to investigate on the calcareous nannofossils at the upper part of Neyzar Formation and the lower part of Kalat Formation in order to determine the exact age of the strata in Tange-Neyzar section. For determining the paleoenvironment, the calcareous nannofossils paleoecology has been investigated.

Fourteen samples from the upper part of Neyzar Formation and 6 samples from the lower part of the Kalat Formation have been studied. Systematic sampling in every mater has been done. For studying calcareous nannofossils regarding biostratigraphy and paleoecology simple smear slides (Perch-Nielsen, 1985) were prepared. For calcareous nannofossil biostratigraphy Sissingh (1977) biozonation emended by Perch-Nielsen (1985) and Burnett (1998) zonation have been applied.

From the base of the section, species such as Reinhardtites Levis, Ceratolithoides aculeus, Uniplanarius sissinghii, Eiffellithus parallelus are present. The first occurrence (FO) of Reinhardtites levis is a marker for the middle part of UC14dTP, the FO of C. aculeus indicates the boundary of UC15aTP and UC15bTP subzones, the FO of U. sissinghii marks the boundary between UC15bTP and UC15cTP, and the FO of E. parallelus shows the boundary between UC15cTP and UC15dTP subzones. From the early parts of the section, E. examine is present that its LO indicates the boundary between UC15 and UC16 biozones and is observed up to the end of the section. According to the mentioned taxa, calcareous nannofossil subzone UC15eTP with early late Campanian age was identified at the studied interval. The presence of taxa with cold water affinity like M. decussata, Prediscosphaera spp., Eiffellithus spp., A. cymbiformis and A. octoradiata and the absence of warm water taxa indicate decrease in temperature and cool greenhouse condition. Micula decussata which marks cool, oligotroph and stressful condition (Pospichal and Wise, 1990; Thibault and Gardin, 2006; Watkins and Self-Trail, 2005) is dominant at the studied interval. Prediscosphaera spp. is also abundant and is a marker of cold (Watkins and Self-Trail, 2005) and oligotroph (Friedrich et al, 2005) surface waters. The highest relative abundance of W. barnesae which is a warm and oligotroph taxa (Thierstein, 1981; Lees, 2002; Sheldon et al, 2010) is recorded at the lower part of the section, Lithraphidites carniolensis with warm and oligotrophic affinity is common is stratified photic zones (Friedrich et al, 2005) that its highest relative abundance is recorded at the lower part of the interval. Eiffellithus spp. with the highest relative abundance of E. turriseiffelii at the lower part of the section is considered as an oligotroph taxa (Friedrich et al, 2005). The highest relative abundance of A. cymbiformis with cold surface water affinity (Thierstein, 1981; Barrera, 1994; Watkins and Self-Trail, 2005) is recorded at the lower part of the section. The highest relative abundance of B. bigelowii is also recorded at the bottom of the section. In the Zagros sedimentary Basin, C. ehrenbergii is considered as cold water taxa, but a decrease in the depth is also important (Razmjooei et al, 2020).

According to the calcareous nannofossil taxa at the upper part of the Neyzar Formation and the lower part of the Kalat Formation, UC15eTP subzone equivalent with the upper part of CC22 biozone of Sissingh emended by Perch-Nielsen has been identified. Because of the week preservation of the calcareous nannofossils, U. trifidus was not recorded. Species such as E. eximius and R. anthophorus that are markers of the uppermost part UC15 and CC22 are recorded up to the top the section. Regarding these data early late Campanian age was determined for the studied interval. The dominance of cold water taxa like M. decussata, Prediscosphaera spp., Eiffellithus spp. and A. cymbiformis and the absence of warm water taxa indicate cool greenhouse condition at this time interval similar to other parts of the world.

The NE-trending Torud-Chahshirin metallogenic belt, lying in the central to the eastern portion of the Alborz Mountain system is approximately 300 km in length, with a complex tectonic, magmatic, and stratigraphic history (Alavi, 1996). The major ore deposits of the Torud-Chahshirin metallogenic belt (Fig. 6) include many mineral occurrences and abandoned mines, particularly epithermal precious and base metal veins, hosted by volcanic and subvolcanic alkaline rocks, such as Gandy, Abolhassani, Cheshmeh Hafez, Ghole Kaftaran, Pousideh, Darestan and Chahmessi (Shamanian et al, 2004; Fard et al, 2006; Mehrabi and Ghasemi, 2012). In addition, other types of deposit in the district include turquoise and placer gold at Baghu (Au ± Cu), Fe–skarn deposits at Chalu, and Pb–Zn (Ag) carbonate-hosted deposits (MVT) at Reshm, Khanjar and Anarou (Shamanian et al, 2004; Niroomand et al, 2018). The Northern Chah-Farsakh deposit is located 75 km south of Damghan city, and lies within the western part of the Torud-Chahshirin metallogenic belt. This paper describes the local stratigraphic and geological features together with, the relationships between the copper mineralization and the host rocks. Descriptions are supplemented by fluid inclusion studies to constrain the conditions for the genesis of the Northern Chah-Farsakh deposit.

This study focused on the geological and mineralogical of the Northern Chah-Farsakh deposit. Determination of the mineralogy and paragenesis of the deposit is based on logging of drill cores and petrographic studies of over 48 polished thin and thick sections, supplemented by XL30 scanning electron microscopy conducted at Tarbiat Modares University. Doubly polished wafers using standard techniques were prepared from seven samples collected in the presumed feeder zone of the Northern Chah-Farsakh deposit. Micro-thermometric measurements of fluid inclusions were performed on a Linkam THMS 600 combined heating/ freezing stage with a German Zeiss microscope at the Tarbiat Modares University, Iran.

The Northern Chah-Farsakh copper deposit is located in the Torud-Chahshirin metallogenic belt and formed in the Neoproterozoic-early Cambrian volcanic-sedimentary sequence. Mineralization occurred in the form of a sulfide horizon in the meta-volcanic rocks. It formed less frequently in the hanging wall units of meta-volcanic, including the muscovite- quartz schist, the meta-sandstone, the tuffaceous sandstone, and the marble units. The main ore minerals in the deposit include chalcopyrite, pyrite, sphalerite magnetite, pyrrhotite, tetrahedrite, tennantite and bornite, respectively, and the secondary minerals include covellite and chalcocite, and the most abundant gangue minerals are quartz and calcite. Based on the orebody structure, mineralogy, and ore textures, we recognize tree different ore facies types in the Northern Chah-Farsakh deposit: 1) stockwork/feeder zone; 2) massive ore facies; and 3) bedded ore facie.  Siliceous and carbonate alterations are the main alterations associated with mineralization. Banded, disseminated, replacement, massive, veins-veinlets are main ore-bearing textures in this deposit According to fluids inclusion studies on the quartz minerals of the stringer zone, the average homogenization temperature of the fluids inclusions is 355 °C and the salinity is 6 to 16 wt% NaCl eq.

According to geological studies, mineralogy, structure and texture and fluids inclusions the Northern Chah-Farsakh deposit is formed in the submarine volcanic activity environment and this deposit shows most similarities with the Besshi-type VMS mineralization.