نشریه کواترنری ایران
پیاپی 25 (بهار و تابستان 1400)

Climate, as the average temperature or precipitation over a long period of time, is constantly fluctuating and changing. There is a complex relationship between climate change and human biological and cultural reactions (Weeks and Petrie, 2018). Increased dry conditions in the subtropics is one of the consequences of climate change that has been predicted by various models. While using the results of various paleo climate archives can reconstruct the climatic conditions of the past several thousand years and provide more accurate forecasts for the future. Due to the fact that the physical and chemical properties of sediments have an extraordinary power in recording climatic and environmental events with high sensitivity, so the use of sedimentary geochemical results in identifying and reconstructing the effects of dry climatic events is one of the most common method (Sai, 2004).

In order to identify and reconstruct the Middle and Late Holocene dry events, a 2-meter sediment core was used from the middle part of Heshilan marshland. The coring was performed using a Russian coroner. In this study, 5 samples were analyzed by radiocarbon method (C14-AMS) at the Institute of Physics and Astronomy, University of Aarhus, Denmark. Magnetic susceptibility measurements of the samples and measurements were performed using a COX Itrax CS37 scanner at the Bartington MS2C magnetometer at the Geogenetics Laboratory of the Copenhagen Geological Museum in Denmark. The magnetic susceptibility of the samples was measured with an accuracy of 5 mm and the Itrax analysis with an accuracy of 1 mm.

The study of climatic events of the last six thousand years showed the fluctuation of climate between cold, dry and warm phases in the study area, which was consistent with the climatic events of the northern hemisphere. The results showed that dust storms occurred in the period of 5400-5200, 4850-4700, 4200-3700, 3400- 3250, 2300-2100 and 1700-1500 years ago in the region. The length of the region's dry climatic periods has often been 200 years. The longest dry period identified in the region dates back to 4200-3700 years ago.

Epithermal deposits are usually found in association with near-surface magmatic-hydrothermal environments with volcanic rocks. According to studies, their formation depth is less than 1.5 km and the temperature for their formation is less than 300 ° C. Epithermal deposits are usually rich in gold to gold-silver and rich in silver and include low sulfide, medium sulfide and high sulfide types. One of the anomalous areas for mineralization of epithermal type gold is located in the area of Zavarian in Qom, central Iran. The following article is about some results of our research about origin of Quaternery placer in the area of Zavarian.

The collected samples were chosen from samples which are associated with mineralization and host rock for geochemical studies. Samples were selected after field and petrographic studies. ICP-OES and Fired-Assay analize measurements were made on 120 samples and ICP-MS analize were made on 8 samples. Aster images were analized with ENVI for remotesinsing study.

Petrographic studies show that 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. The results of remote sensing and geochemical investigation suggest that the origin of hematite, magnetite, Purite, chalcopyrite and galena are volcanic- pyroclastic units of Miocene- Pliocene in quaternary placers. The results of ICP-OES and ICP-MS show that the average grade of gold in the study area is 1.36 ppm, which is 194 times richer than the average of earth crust (0.007 ppm). The maximum gold grade in the mineralization zone is 10.76 ppm. The average grade of silver is 2.69 ppm, which is 44.8 times richer than the average of earth crust (0.06 ppm). The average grade of copper is 1236 ppm and it is 40.19 times richer than the average of earth crust (30 ppm). The average grade of iron is 175707.9 ppm and it is 3.51 times richer than the average of earth crust.

Zavarian gold deposit is located 60 km SW of Qom and in Central Iran geotectonic zone. Gold mineralization has been occurred in andesite and dacite dykes which are associated with advanced argillic, alunitization, propylitic, sericitic and silicification. 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 is 1.98ppm. Mineralogical, geochemical, alteration data show that gold mineralization in the area is epithermal high sulfide type. Also, the presence of chalcopyrite, bornite, Au-Cu-As- Ag- Pb, advanced argillic-alunitization, vague quartz texture, vein-veinlet-breccia and replacmente mineralization type support this idea too. The results of remote sensing and geochemical investigation suggest that the origin of hematite, magnetite, Purite, chalcopyrite and galena are volcanic- pyroclastic units of Miocene- Pliocene in quaternary placers.

Rivers are one of the most important water resources and it is very important to study their water quality. Therefore, in this study, sampling was done from 15 permanent waterway stations of Pirbadush and Gashun of Qolyan River in Lorestan province, which are located in the path of oil shales.

 Hydro-geochemical parameters were calculated by analyzing the samples in the laboratory. Then compared with drinking water quality assessment standards in the region and Hydro-geochemical diagrams were also drawn.

Qolyan River water contains a lot of calcium carbonate and only sample P3 has more magnesium carbonate that it is unsuitable for drinking due to its high calcium content, but it is suitable based on other parameters.

According to Schoeller quality classification, Gashun samples are of lower quality than Pirbadush and by the standards, most samples are within the allowable-favorable range and water of G6, G7, P5 stations have lower quality than other stations. According to the WHO table, the water of the Qolyan River is relatively light in terms of TH and total dissolved solids (TDS) and relatively light in terms of Electrical conductivity (Ec). Based on hydro-chemical tests and data analysis and hardness estimation and comparison with the national standard of Iran and the standard of the World Health Organization, the results of water classification of the samples are as follows: According to the World Health Organization's calcium ion (Ca2 +) content, water samples from G7 and P5 stations are impermissible and based on the total hardness of the Iranian national standard, the water samples of stations P1 and P3 are in the favorable level.According to hydro-geochemical diagrams, the water quality of Pirbadush waterway is better than Gashun. According to the Piper diagram, In Gashun samples, the tendency of the samples towards magnesium and sulfatation is more than the samples of Pirbadush region. According to the Durov diagram, most of the water samples taken from Gashun and Pirbadush waterways are calcium carbonate (Ca-CO3) and calcium bicarbonate (Ca-HCO3). According to Schoeller diagram, the amount of tumble in the samples of Gashun waterway is more than Pirbadush waterway. According to the ion equilibrium diagram, the amplitude of change of anions and cations in Gashun waterway is more than Pirbadush. According to Stiff diagram, the different origins of the samples indicate the existence of several bedrock sources for the samples, and according to the Gibbs diagram, bedrock and weathering and dissolution are the main factors controlling the water chemistry of the region.By examining the water quality of Qolyan River in Pirbadush and Gashun waterways with any human activity that it is in the path of oil shales, the results were obtained which are:-The highest amount of cations and carbonate anion (CO32-), is in G7 station andthe highest amount of nitrate anion (NO3-), are in G6 and P7 stations.-The highest water total hardness (TH) is related to stations G7, G6, P5 and the lowest is related to stations P3, P1, G1.-The highest total dissolved solids (TDS) in water is related to stations G6, G5,  G7 and the lowest amount is related to P1, P4, P3.- The presence of higher amount of calcium carbonate (Ca-HCO3) in Gashun waterway than Pirbadush indicates a higher degree of solubility of calc than dolomite in this section.- High sulfate content in Gashun waterway (especially G1 station) can be related with further dissolution of anhydrites in the Gotnia Formation.-Anion and cation equilibrium also shows that ionic equilibrium is present only at stations G3, G5, P6. However, at stations P1 and P3, there is a high degree of ionic imbalance between anions and cations.
 

 In this area, the type of rock units and even the presence of oil shales have not had a detrimental effect on the quality of drinking water.

Haji-Arab River is a seasonal river in the south of Qazvin province. Quaternary alluvial deposits in Qazvin province spread on wide range. Since many coherent studies in terms of geology, sedimentary environment, mineralogy and climatic conditions have not been done in the mentioned sediments, so this study has been done to study the sediments of this river and determine its sedimentary facies. Therefore, the results of this study can provide a more precise understanding of the sedimentology status and sedimentary environment of this area.

This study was conducted to investigate the sediments of this river and to determine its sedimentary facies. Sampling was done from 4 boreholes and trenches around the ancient Qara Tappeh hill. Sediment granulation has been done by dry sieving, wet sieving and laser shaker sieving. Sedimentological studies show that the occurrence of frequent floods in the region has changed the texture of channel sediments and changed various parameters of particle size. Haji-Arab River, flows from south to north direction. This river originates from the central mountains and extends to Sagz-Abad. Sampling has been done around the ancient hill of Sagz-Abad (Qara-Tappeh) with an altitude of 1274.9m above sea level. This hill is located 52 km south of Qazvin (7 km north of Sagz-abad of environs Buin-Zahra city) and 132 km west of Tehran. Sampling were done in September 2016. The boreholes and trenches were excavated by Department of Archaeology, University of Tehran. From 4 boreholes with a maximum depth of 8.3 meters, 57 samples have been taken from around the ancient hill of Qara-Tappeh. Collected samples were dried due to humidity outdoors. 15% of the samples were granulated in two forms: dry and wet. Since the result difference was more than 10% due to grains adhesion, other samples were sieved by wet method. Particles smaller than 4µm were granulated by laser shaker sieving. Statistical parameters such as kurtosis, sorting, skewness and mean were calculated using Gradistat software. Also In this study, sedimentary facies were studied using field and laboratory methods. Sediment type was named based on Folk (1974) classification and facies classification based on Miall classification (1996, 2006). Finally, by combining all the data, a sedimentary model for Haji-Arab River was offered.

The study of sediments in this river led to the identification of three categories of sedimentary facies, which are: mud facies (Fl, Fm, Fr), sandy facies (Sm, Sp, Sl, Sh) and gravel (Gh, Gcm, Gms, Gci, Gmg, Gmm), which have settled in different parts of the river environment. Based on the identified facies, structural elements Floodplain Fines (FF), Sandy Bedforms (SB), gravelly Bars and Bedforms (GB), Sediment Gravity flow deposits (SG) and channels (CH) have been formed in this sedimentary basin. Sedimentary models of this river include Fine-Grained Meandering River, Sand-Bed Meandering River, Gravel-Bed Braided River and Shallow-Gravel-Bed Braided River.

Generally, coarse-grained, sandy and fine-grained sediments, poorly to very poorly sorting, absence of fossils, light color of sediments, the presence of plant traces indicate that the Quaternary sediments of the study area form in river system which include sub-environments such as, Channel, off-channel and floodplain deposits. Examination of sediment sequence in the study area shows the transition from a humid and low-energy environment to a dry and high-energy environment during the Quaternary. According to field studies and studies of sedimentary facies of Haji-Arab River, silt sediments are the most widespread in Haji-Arab catchment. Gravel with lower percentage are observed in limited parts of the basin and in the upper parts of the studied sequences. Therefore, based on the above evidence and the characteristics of facies in the Miall (1996) classification, fine-grained sediments have been deposited in the meandering River and coarse-grained sediments of this region have been deposited in a braided river. According to the studies, the architectural elements of FF, CH and SB and to a lesser extent GB and SG can be considered for this basin. Based on this, Can be considered 4 river models including fine-grained meandering rivers, Sandy meandering river, gravel wandering river and shallow gravel bed braided can be used for Haji-Arab River in the study area.

Study of area (Golpayegan area) is located in the Sanandaj-Sirjan structural zone, which is one of the most dynamic tectonic seismic zones in Iran. Among the most important faults of Janba in the study area, we can mention Khansar, Hila, Narpalang, Boland Ab, Qara No, Bid Arab faults. In this study, a theoretical model is proposed to evaluate the Fault Movement Potential based on the relationship between the geometric properties of the fault and the regional tectonic stress field. This model by et al. (1997) Lee, and has been used to evaluate the mobility potential of major faults in the Hong Kong area. This parameter allows for the percentage of possible movements in the current tectonic regime (CTR) for all active faults in a range. It should be noted that the results of this method are consistent with past seismic records and current micro-seismic activity in the region, so this theoretical model is based on the relationship between the geometric properties of faults and the regional tectonic stress field. To evaluate the mobility potential of active faults in Golpayegan area in the northwest of Kush to the southeast of Bid valley, the structural zone of Sanandaj-Sirjan.

 Structural data were collected in a large area of ​​the study area in order to achieve the position of the main stress axes. The equations of this model were used in 6 stations in the mentioned area. Finally, using the inversion method, the maximum maximum stress in each section was obtained separately and placed in the equations.

According to the calculations, the motion potential of the fault in each section of the faults in the area was determined that the Arab willow fault has the highest movement potential compared to other fault parts, which according to the calculation of the mountain frontal maze index is well visible. Category 1 tectonics with high activity, other faults are in the pre-seismic stage. The results of calculating the potential of faults in each section show a good agreement with the frequency of earthquakes, so that the eastern part of the study area has a higher seismicity rate than other parts. Due to the average landslide velocity of faults in recent years and also according to previous studies and results obtained from the area and data from the calculation of fault potential values, the eastern part of the area (the distance between Arab willow fault and male leopard fault ) Has the highest probability of slipping in the future. The southern part of Bid Arab fault is associated with the highest mobility potential of the fault and the tectonic structures of its areas are introduced as the youngest neotectonic activities in the area.

Changes in land surface shape in active tectonic  zones result from interplay between tectonic forces and surface processes (Keller and Pinter, 1996; Keller et al., 1999). Salt Domes  are dome-shaped Geological structures whose central core is composed of salt. Their economic importance is due to the location of oil tanks in structures with salt domes and also the presence of sulfide sources of potash, iron and salt in them. Zagros region, in which Koohrang city is located, is a pressure zone where Koohrang fault is located in the southwest, Dehno fault is located in the east , Mohammadabad fault is located in the north of and Zardkuh fault is located in the south of salt dome. In the meantime, the salt dome has come to the surface with a lower density due to the movements of faults and stress from the Arabic plate to the Iranian plate. There are many linear springs in this area, which are faults and indicate the activity of faults in the area.

In this study, in order to evaluate the new construction activity of the region, the location of Koohrang salt dome was determined, using Baba Haidar 1: 100000 maps, Shahrekord 1: 250,000 map.  Using the data of these maps as basic data in ArcGis software (10.3), drainage network and digital elevation model (DEM) of the study area were used as basic elevation data. Using the data of these maps as basic data in ArcGis software (10.3), and digital elevation model (DEM) of the region and ArcHydro toolbar, 98 basins were considered for the study area. Then, according to the characteristics of the region, drainage basin asymmetry index (Af), hypostometric integral index (Hi),stream length gradient index (SL), mountain front sinusitis index (Smf), valley to depth-to-depth ratio index (Vf), index Relative activity (Iat) was calculated for the study area and the results of each index are plotted. 

In terms of basin asymmetry index, 36 basins are active in class 1 and in terms of tectonic activity, 38 basins are moderately active, 24 basins are in class 3 and have low tectonic activity. In terms of hypsometric integral index, 15 basins have new active tectonic activity (their height is higher than the average height of the study area, high areas with deep incisions), 17 basins are in class 2 and have medium activity and 66 basins have low tectonic activity. For the SL index, 19 basins in class 1 have high tectonic activity, 8 basins in class 2 have medium tectonic activity, 34 basins in class 3 have low tectonic activity and 37 of its basins have very little new tectonic activity, which are located near the main river. For the mountain frontal sinusitis index, 28 basins have high tectonic activity, 12 basins have medium tectonic activity, 7 basins have low tectonic activity and 51 basins have very low activity (data not obtained). The highest value of Smf index is 1.04 for basins 2, 13, 23 and the lowest value is 1.69 for basins that are in class 3 and yellow in the map . The lower the value of the index, the more active the tectonics of the region and the straight mountain fronts. In valley to depth-to-depth ratio index, a number of basins that cut off the mountain winding all include V-shaped and young valleys. In the general survey, 8 basins are very active, 16 basins are active, 54 basins have low tectonic activity and 20 basins have very low tectonic activity.

In this study, according to the measurement of stream length gradient index (SL) , drainage basin asymmetry index (Af), mountain sinusitis index (Smf), hypostometric integral index (Hi), valley width to depth ratio index (Vf), Relatively active tectonics index (IAT) has been used to study the relative active tectonics activity of the region. According to the zoning map obtained from the above indicators, the most activity in the study area is related to the basins that have active faults and high activity of the newest structure can be seen in the heights of Klonchin, Khadang Valley and Zardkooh. In this area, Koohrang salt dome and agricultural lands, Koohrang city and Dehno village have low to medium activity. The more we move from the Koohrang salt dome to the heights of Zardkooh, the more and more active the new tectonic activity of the region. Evidence from the diversion of streams, digging the bed of alluvial fans, V-shaped valleys and triangular shapes in the study area show high neotectonic activity This part (Zardkooh heights) of the study area.

The Bafq-Baghin fault system is one of the major faults in Central Iran and parallel to the Kuhbnan fault in the northeast and the Rafsanjan fault in the southwest. This fault system, under the influence of the stress, is the maximum that results from the convergence of the Arabian plate towards Iran plate has a right-strike with a compression component.  The study area is located in central Iran and its southeastern part. In the last division of central Iran, this region is located in the Poshtbdam.

 Using satellite images and related software and integration with field data, fault system components were identified and mapped. Morphotectonic relationships and formulas were used to analyze the tectonic morphology of the region. Active strike-slip faults, especially those on the mountain front, usually appear as separate sections. By processing satellite images of the region and based on the study of building parameters, geometric condition, tracking along the fault system, examining changes along the direction, motion and branching sub-structures along the system, it was determined that the Bafgh-Baghin fault-slip fault system is like most active faults. It is formed in separate pieces.

  By studies performed during the system, 60 fault pieces were identified. Bafgh-Baghin fault sections were examined for tectonic morphology, which is evidence that the Bafgh-Baghin fault system is adjacent. In the direction of fault sections, fault precipices have been formed, which in some cases, several-meter precipices were observed. Folds with strike-slip faults are usually stepped and sloping to the main cutting direction. The term en echelon refers to the arrangement of buildings in a linear zone, so that the folds or faults are parallel to each other and have the same tendency towards the direction of the linear zone. The naming of en echelon folds is based on the displacement of the right-slip zones that create them, so that right-slip faults create right-handed folds and left-handed right-slip faults create left-handed folds. Due to the right-slip activity of fault sections, some folds in the mountains have become right-stepped. Large amounts of Vf are associated with low uplift rates, ie low tectonic activity, in which rivers have relatively wide bottoms. Low Vf values refer to deep valleys in which rivers actively dig valleys and are usually associated with active tectonics and uplift.Mountainous fronts associated with active tectonics have sinusoids (Smf) between 1.6 and 1. Low-activity mountain fronts have sinusoids between 3 and 1.6, and inactive mountain fronts have sinusoids of about 3 to values greater than 5 because of high erosion and inactive tectonics. The low values of mountain front page maze (Smf) and the ratio of valley width to valley depth (Vf) calculated in the direction of fault plots indicate fault and tectonic faults of the region. Wherever the strike-slip fault becomes stepped or bends, due to the movement of the fault in these areas, it either suffers from divergence and tensile forces that lead to elongation and pull-apart basin, or suffers from convergence forces that result. They create compression and pressure in the basin. In the pull-apart basin, normal faults and subsidence are created and it is a suitable place for sediment accumulation. In the compressive basin, compressive ridges and inverse faults are formed. Due to the fact that Bafgh-Baghin fault sections have a strike-slip mechanism, where the pieces are placed relative to each other, pull-apart basins and compressive basins are formed between these fault sections. With the strike-slip activity of the fault sections, pull-apart basins have been created between some fault sections that are staggered relative to each other. In one of the pull-apart basins of the region, a fertile village called Khanaman has been formed on the southwestern front of the Bafgh-Baghin fault system.

The sediment cores BAG, AZD and AM in the Babolsar, Jouybar and Zaghmarz areas are located at the southern Iranian part of the coastal plain of the Caspian Sea. These areas are contained by major mountain ridge, the Alborz in the south (Central Alborz Structural Zone). The Alborz Mountain represent the main source of terrigenous materials in the South basin of the Caspian Sea. The geology of the southern part of the Caspian Sea catchment include sedimentary deposits, loess and terrasses, volcanic rocks, Precambrian metamorphics and Jurassic massive limestones (Aghanabati 2004; Lahijani and Tavakoli 2012).Sedimentary facies are controlled by physical processes such as velocity, depth and type of flow and sediment transport rates (Catuneanu 2006). Sediments are deposited in various depositional environments based on physical, chemical, and biological processes (Fursich, 1995; Walker, 2006). This study focuses on the interpretation of sedimentary facies, sedimentary environment and geochemistry of the sediments from the core successions. The results of this study can be useful in the palaeoenvironmental reconstruction in the southern Iranian part of the coastal plain of the Caspian Sea through the Quaternary time.

Detailed field investigations were carried out on the three core sediments from the Babolsar, Jouybar and Zaghmarz areas. Using the rotary drilling machine, cores BAG, AZD and AM were obtained during 2016 fieldworks. A total of 88 representative samples were collected from three cores at different depths for the sedimentological (46 samples) and whole rock geochemical (42 samples) analyses. After collection, selected samples were sealed in polyethylene bags and then air-dried in the laboratory. The granulometric characteristics and textural properties were determined using Sieve analysis. Then, 46 samples were classified following Folk’s (1974). Subsequently, the 42 samples were powdered to less than 200 mesh using an agate mortar. The selected major and trace elements concentrations were measured using an Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) at the Geological Survey and Mineral Exploration, Tehran, Iran.

Based on the sedimentological characteristics, cores BAG, AZD and AM have been divided into three lithofacies. They include sandy mud, muddy and sandy to silty sand lithofacies. Sandy mud lithofacies is characterized by pale-yellow to light-brown (partly mottled), poor sorting with a maximum thickness. This facies is also dominated by massive to rarely thin lamination, abundant plant fragments and roots, individual shell fragments, and lack of marine fossils. The presence of plant roots and pale-yellow to light-brown colour and massive to thin lamination claystone facies indicate suspension fallout from standing water in floodplain setting (Selim 2017).Sandy/ silty sand lithofacies is supported by the presence of unconsolidated lightly gray silty sand, moderate to well sorting, with high bivalve contents and the deposition of alternating layers of silt and fine to coarse sand. This lithofacies has an unclear and irregular boundary with the underlying facies and has up to 1 m thickness. Coarse-grained texture with moderate to well sorted particles indicate deposition under high-energy conditions in a beach setting (Sim and Lee, 2006)Muddy facies consists of poorly sorted, alternative horizons of light green to dark grey-coloured silty clay, with the thickness varies from 0.5 to 2 m. In this lithofacies, foraminifera and ostracod shells, endogenic gypsum mineral as well as calcite were also observed. The fine-grained texture, dark gray to black colored and the presence of foraminifer and ostracod shells indicates deposition may have taken place under low-energy environment in a relatively reduced oxygen contents lagoon (Geel, 2000; Corda and Brandano, 2003; Amao et al., 2016)The behaviour of Ti/Al, Fe/Al, Zr/Al and Si/Al can be exploited to acquire information on grain size (Dypvik and Harris, 2001). In the studied cores, Ti/Al and Fe/Al, and Zr/Al and Si/Al ratios show well correlations in the fine- and coarse grained horizons, which is matched by the muddy and sandy to sandy mud facies, respectively.In finer-grained sediments, Rb/Zr can be used as a proxy for changes in grain size, with lower values representing fine-grained material and higher values representing coarse-grained material. Increases in Zr/Rb proxy is matched by an increase in the coarse fraction in the sandy and sandy mud facies, as evidenced by the grain size analysis. A decrease in the Zr/Rb ratio is matched by an increase in clay fractions, in the muddy facies.

 The sediment cores BAG, AZD and AM in the southern Iranian part of the coastal plain of the Caspian Sea, are dominated by mud and sand fractions. These sediment cores represent the Sandy mud, Sandy/silty sand and Muddy lithofacies. These lithofacies were deposited in the flood plain, beach and lagoon environments, respectively. The geochemical behaviour of most elements, in a general way, is related to the grain size in the sediments. Samples with high Si/Al and Zr/Al ratios are generally coarser grained, while high Ti/Al, Fe/Al and Rb/Zr are related to fine-grained samples.

The study of tree rings is one of the most widely used methods of climate reconstruction for centuries and millennia, but the occurrence of climatic anomalies such as global warming in recent decades has caused divergence problem in the series of tree rings in some areas. Which challenges the ability of this proxy to regenerate the climate. The “divergence problem” is the difference between the recorded temperatures and the regenerated temperatures using tree rings in the forests of the northern high latitudes. While the data recorded by thermometers show a significant warming trend in the late twentieth century, many of the chronologies obtained from the sites mentioned do not show a similar change in ring width. Reconstruction of past temperatures in divergent chronologies overestimates past reconstructed temperatures. The present study tries to investigate the occurrence of "divergence problem" in low latitudes using juniper growth rings in the north of Kerman province in Iran and provide a solution for temperature reconstruction according to the chronologies with this problem.

The study area of this study is one of the lesser-known habitats called “Tangal Ravar”, located in the northern highlands of Kerman province in Iran at the 31°25' of North and 56° 50' of East. In the spring of 2018, more than 200 tree ring samples taken of juniperus trees. Chronologies created in ARSTAN software by BiweightRobust averaging method, and then de trending and standardized by negative exponential curve method and 20-year spline, Climatic data were prepared from two synoptic stations of Kerman and Zarand to investigate the relationship and correlation of climatic factors with the ring width index and reconstructions. For better comparison of these two stations, CRU TS4.01 data with the statistical period of 1901- 2016 for Iran, also used. In this study, two methods used to reconstruct the annual temperature. In the first method, first the temperature threshold (according to CRU temperature data) is determined and then by dividing the years, from data above the threshold to construct a regression relationship of the divergence period with inverse correlation and from data below Thresholds were used to construct the regression relationship of the pre-divergence period with direct correlation. In the second method, multivariate regression used between temperature data, ring width and precipitation for the statistical period of 1901-1995. The reconstructed precipitation used for multivariate reconstruction until the end of the chronology.

The results of comparison between temperature data and tree rings chronology index of the studied habitat showed that the trees of this habitat have been suffering from divergence since the mid-1990s. Initially, the results of correlation between station temperature data and average chronology of the region showed a generally negative relationship and it concluded that air temperature throughout the year has a negative correlation with the growth of juniper trees in the region and in general, this factor is a limiting factor. , But this is not consistent with most research on the subject. Temperature reconstruction in this case showed an inverse function of the chronology chart trend due to the negative relationship. Therefore, using a negative relationship to reconstruction temperature over a long period led to meaningless estimation during periods of severe reduction in rings width. However, with the removal of the 1996-2016 period from the data series, the correlation results underwent extensive changes to positive. The results showed that in years with an average temperature between 17 to 17.5 degrees and sometimes from 16.8 to 17.8 degrees, there is no significant relationship between the width of the rings and the temperature, and this temperature range can be considered without regard to taking the role of precipitation, the optimal growth temperature. At temperatures below 17 or possibly 16.8 degrees there is a direct correlation and at temperatures above 17.5 or possibly 17.8 degrees there is an inverse relationship between growth and temperature. In addition, comparison of chronology with climatic trends showed that precipitation has a more decisive role in the radial growth of juniper trees. In this regard, the reconstruction results showed that the use of bivariate regression and the application of precipitation for the second variable, despite the smoother data estimation than the real data, in general show better results than data segmentation based on temperature threshold.

Examination of station temperature data with chronology obtained from the region showed that due to the increase in temperature along with the relative decrease in precipitation in recent decades, temperature data with the chronology of ring width have diverged. Therefore, in order to reconstruct the temperature and study the climate / growth relations in the region, it is necessary to carefully study the relationship between This divergence for the study area has clearly started in 1996 and has continued until the end of chronology in 2017, for more than the last 2 decades. The time difference between the occurrence of the "divergence issue" in the study area and the northern areas is about 40 years. This issue can be related to the occurrence of later increase in temperature averages in the study area compared to high latitudes and the greater impact of juniper trees in arid regions such as the north of Kerman province from moisture. So that the increase in air temperature alone is not able to limit the radial growth of juniper trees and the creation of moisture stress is necessary for this issue, this stress has obviously occurred since 1996 with successive droughts in the region. The results showed that due to the location of the study site in a dry area, the use of precipitation as a second variable gives better results for temperature reconstruction. Finally, the regenerated temperature shows an increase of about 1.5 degrees in global warming in recent decades. In addition, except for an increase in the decades 1740-1750-1760, a decrease of 0.5 to 1.5 degrees of temperature compared to the long-term average from about 1820 to 1520 AD can be considered the reaction of juniper trees in the region to the Little Ice Age.

Quaternary placer deposits are becoming increasingly important. Remote sensing is a very powerful tool in discriminating altered areas related to intrusion deposits, which has significantly reduced the cost and time of exploration. In this study, to identify iron-bearing alluvial zones within the 1:100000 sheet of Hamedan, satellite image processing techniques such as band ratio (BR), false color composition (FCC) and spectral angle mapper (SAM) on visible and near-infrared plus shortwave infrared bands (VNIR + SWIR)  of ASTER sensor is used. Important exploratory data such as geological maps, faults and lineaments, magnetometer and band ratio applied to ASTER sensor data, distribution of Ferrous iron (Fe2+) and Ferric iron (Fe3+) were created and combined with weighted overlay index (WOI). Then important iron-bearing minerals such as magnetite, hematite, limonite and goethite were identified by spectral angle mapper (SAM). The iron ore in study area was also detected by the false color composition (FCC) method and the results of SAM and FCC methods were compared to weighted overlay index (WOI). With regard to the field visit and  well conforming the results of all three methods, in the absence of complementary exploratory data such as geochemistry and geophysics, the results of SAM and FCC methods can be adduced singly or with each other.

The study area is located in Eshtehard plain and in front of the Alborz mountain range. Eshtehard and its surroundings are in the range of seismic faults such as ipak fault in the south and north Eshtehard fault in the north. In the past, based on the evidence and phenomena of earthquakes and historical earthquakes attributed to Sagzabad, in the alluvial zone of Jaroo Mountain in Eshtehard plain, linear phenomena accompanied by obvious precipices such as the scarp of the south of Eshtehard are among the fault scarp Have been categorized. In this study, based on the data obtained from paleoseismology, geomorphology, geoelectric characteristics presented in this study, it seems that the southern part of Eshtehard is not a sign of a fault, but the result of a fold in the Red Formation. It is high which shows the morphological nature of the southern part of Eshtehard, which was previously introduced as the southern Eshtehard fault. This fold is a simple curvature of the layers that has been achieved during the Late Cenozoic due to the shortening of this part of the Alborz mountain range.

For conducting paleoseismological studies in the study area, tectonic morphological features, geophysical surveys (2 geoelectric and geomagnetic sections) were performed. Finally, a site in the east of Eshtehard was selected and 4 trenches perpendicular to the scarp were dug. Then, structural phenomena and sediment-stratigraphic deposits on the trench walls were separated and studied. In this paper, the results of trench studies are presented.

Conclosion:

The results of additional studies such as paleo-seismic studies (with excavation of 4 trenches) and geophysics (magnetometric and geoelectric), show that the layers, horizontal and without any signs of young faults in the trenches (maximum depth 4) M) that even rejects the possible lateral and hidden faults in the depths;Because if there was such a fault in the area of ​​the southern part of Eshtehard, the mapped deposits of the existing partition trenches would have to be deformed. This indicates the morphological nature of the southern part of Eshtehard, which was previously known as the South Eshtehard fault. Thus, attributing this scarp to an active fault does not seem correct. However, the question remains why and how the scarp was formed? Our field observations show that the deposits in the studied scarp are of marl genus and belong to the upper parts of the Upper Red Formation that have been exposed at the surface. The most logical justification for this is the formation of an open anticline. Geoelectric data in the west of Mokhtarabad also clearly show the existence of an anticline in the study area. Accordingly, the formation of a linear complication on marl sediments scarp can be justified by the tensions that generally occur in the outer parts of the folds.

Land degradation is a negative phenomenon affecting the environment and causes a gradual decrease in ecosystem performance. Considering that more than half of the watersheds of Iran are in arid and semi-arid Mediterranean areas, land degradation is important considering the role of these watersheds in water and food production. In land degradation, types of soil degradation, biodiversity and water scarcity have been mentioned as consequences of land degradation more than other consequences. Land degradation can occur due to various reasons, including poor management of the environmental resources and land uses, climatic conditions and environmental land characteristics. Watersheds are sensitive ecosystems that have faced extensive land degradation in Iran in recent years. The present study was conducted with the aim of modeling land degradation at the Taleghan Dam watershed scale in 2021.

This is a descriptive-applied study. Periodic remote sensing data including aerial photographs and images of LandsatTM and ETM + satellites (1987 and 2002) and IRS 2016, visual and DN methods (for further verification) review and periodic analysis of status and characteristics of land use-related features in the environment were and GIS (IDRIS software) was used in this study. Land use map of the studied watershed in 1970 in accordance with the meteorological and hydrometric data in the research area using aerial photographs with a scale of 1: 20,000 and utilizing the technique and knowledge of interpreting aerial photographs and using a desktop stereoscope, after combining with the area map The research was conducted in a GIS environment. From the method used in the model of the Food and Agriculture Organization for estimating soil erosion (EPM) and decision support systems, a practical model is presented to investigate the current situation of land degradation at the watershed scale. This model has 6 criteria and 43 indicators that the sum of their scores in 6 classes determines the status of land degradation.

The results of the studies indicate that the current land use in the study area includes pastures, rainfed agriculture, irrigated agriculture and orchards and areas without use (rock protrusion). According to the result, the relationship between soil erosion intensity and water erosion intensity coefficient in the model in which the spatial factor of land slope is one of the factors under study. There is% (P-value = 0.005) so that the trend of its changes in the studied time periods is incremental. The results of land degradation using the model in the watershed of Taleghan Dam as a research area showed that the intensity of land degradation in 9.5% of the watershed is low, and in 70, 19 and 0.50% of the watershed are moderate, respectively. "It is relatively high and high. Based on the calculation of land degradation coefficient in Taleghan watershed, index values have decreased from 0.56 to 0.46, which indicates a degradation of 17.86% of the range.

Statistics on population growth in the world show that the highest population growth is in developing countries. Thus, it is important to consider the increased global water and food demand in the issue of population growth. It is predicted to reach twice the global need for water and food by 2030 compared to the current situation. In developing countries, it will increase about 2.5 to 3 times. The results of previous research and the present study show that the environmental consequences of land degradation as a risky phenomenon (mostly under the influence of human actions) despite the lack of full knowledge is so "clear and transparent that if the answer to eliminate Not all the challenges arise from it, but it can be sufficient and justifiable in the necessity and necessity of reducing the risks related to the phenomenon of land degradation, even from a social and economic point of view, in addition to the environment. It is suggested that considering the proposed model dynamically, 6 criteria affecting land degradation in the climatic conditions of watersheds include: water erosion facies, lithological characteristics, soil science and slope of lands with land use and vegetation density It can be used as an efficient model in determining the rate (intensity) and extent of land degradation at the watershed scale to accurately identify degraded sites to combat and manage the phenomenon in question at the national level.