Quaternary Journal of Iran

Abstract The surface manifestations of geothermal resources such as thermal springs, steam grounds, fumaroles, mud pools, and geysers in a region along with their locality, geologic control, physical environment, temperature, chemistry, and the rate of fluid discharge are the most important features that should be taken into account for geothermal explorations.
The preliminary activities in the context of geothermal systems in Iran go back to 1975 when an Italian company (ENEL) carried out comprehensive investigations in geothermal fields in this country. Since then, numerous studies concerning geothermal explorations were done in Iran, and many prospect areas were identified. One of these areas considered to be of prime importance is around the volcanic mount Sabalan in Azerbaijan Block, NW of Iran.
In present study, the authors endeavored to assess and discuss the geological characteristics of the geothermal fields around Sabalan volcano with placing special emphasis on geochemical aspects involved in fluids of this field.
 
Method of investigation
Among several cold and hot spring waters in the study area, 48 samples from high fluid flow springs were collected. For sampling of hot springs, the priority was given to those of maximum discharge rate and the highest discharge temperature at the surface.
The chemical analyses of these samples for determination of major and trace elements as well as stable isotopes were carried out in hydrogeochemistry lab at Bremen University (Germany).
The stable isotope analyses (δD and δ¹⁸O) were carried out by using LGR DLT-100 Laser Spectrometer (Los Gatos Research). The analytical precisions for δ¹⁸O and δD were ±0.2‰ and ±1‰, respectively.
Results and Discussion
In the study area, the hot water samples depict temperature and pH range of 9-89ºC and 4.5-8.58, respectively. The total dissolved solids (TDS) vary from 249 to 7006 mg/l.
The results obtained from isotopic analyses of 48 cold and hot spring water samples from Sabalan geothermal system were carried out for determination of δ¹⁸O and δD, and ³H of these waters (see Table 1). The δ¹⁸O values of these samples vary from -13.4‰ to -7.5‰. The δD values range from -77.6‰ to -71.1‰. ³H values vary from 0.1 to 105 TU.
Conclusions

By noting to the considerable abundance of Cl^-, Na⁺, Ca²⁺, and HCO₃^-, the geothermal fluids in this area were chemically categorized as both Na-Cl and Ca-Na-HCO₃ systems. The high concentration values of Cl^-, Na⁺, and Ca²⁺ in this area stems from water-rock chemical reactions, and high HCO₃^- value may be due either to solution of ascending CO₂ gas in underground waters or to dissolution of basement crystalline limestone.
Consideration of isotopic compositions of Oxygen (δ¹⁸O) and hydrogen (δD) show that the analyzed samples were slightly enriched in δ¹⁸O which may be related to the water-rock isotopic exchange reactions. The water-rock interactions caused slight increase in δD as well.

The measurement of ³H in the Sabalan geothermal fluids indicated that the circulating geothermal fluids can be temporally divided in three groups. The first group has ³H values >10 TU and belongs to modern waters. The second group so called sub-modern waters has ³H values within the range of 1-10 TU. The third group which has ³H values <1 TU is regarded to be as old waters.

Abstract   The investigation and analysis of the morphotectonics of catchment area can be helpful in identification of the area’s active morphotectonics and it can also provide us with some significant and valuable information regarding the district's tectonic features and its tectonic activities. Rivers are of such indicators that show extreme reactions to tectonic activities and therefore, the results of investigating their changes and alterations can be a suitable guide for analyzing and determining the amount of tectonic activities of the study area.
     As a river is shaped under active tectonic circumstances, some morphologic alterations would take place in such structures as channels and longitudinal profiles in reaction to tectonic alterations. Investigating the rivers' drainage system is so important especially in thrust systems since these structures show extreme reaction to vertical tectonics and folds. The river’s bedrocks undergo eroding on the ground and their vertical profile alterations are of the most important geomorphological components regarding the development of mountains views. In situations when the river is not capable of removing the gradient anomalies, Knick points would be made; and if it creates a vast area, it would be called Knick zone which would be found in the shape of a waterfall in flow-paths with flow.
    The study area is located in Southern Alborz to Varamin plain and Qom's salt lake. The controlling factors of the area's tectonics include lithology, climate cycle, and structural factors (fold and fault). The northern part of the area (the Southern hill of Alborz) is completely folded and faulty and has made a totally active area tectonically. The highest part of study area is Damavand summit and its height is 5610 meters above sea level. The south area has some hills and mountains; however, they are totally scattered and plains (Varamin plain and the surrounding areas) have occupied most of the space of the area. This area has created a very tectonically active area since it is located in Alborz foothill, and there are so important faults such as Mosha's thrust fault, the thrust fault of north of Tehran, Taleghan fault, Emamzade Davood fault, and in southern areas, garmsar, eivanaki, hesarbon, and gharbilak faults are located. 
    The northern half of the area, which is affected by orogenic activities of Alborz, has shown totally a higher amount of activities comparing to the other parts of the area.  In this article, the active tectonics of the south of central Alborz in catchment areas of Jajrood, Eivanaki, and Hablerood have been measured in ARC GIS 10.1 environment using  river indexes including Hierarchical anomaly (Ha), Bifurcation index (Bi), Hypsometric integral and curve (Hy), Basin shape (Bs), Basin relative relief (Bh), and Drainage density index (ρ). To this end, the study area has been divided into 18 basins and most of the basins related to the northern and north-eastern areas which are located in the uplift zone have recorded high tectonic activities in most of the measured data. Moreover, the basins have been divided into five levels according to the rate of their tectonic activities; level 1 indicates the highest rate of activities and level 5 indicates the lowest.
    After measuring all the indexes, the active tectonic index (lat) was measured for all the study area in order to come up with an overall conclusion. This index also, confirmed other data and observations as expected. A number of 6 catchments out of 18, all of which related to the northern and north eastern areas, revealed the highest rate of tectonic activities, and their activity index was 1. A number of 11 catchments revealed medium activity, and they were mostly related to the central and southern areas of the study area; and only 1 catchment revealed the lowest tectonic activity which was related to the most southern study area. Totally, according to the data collected from the three catchment areas which were investigated in this study, the highest rate of tectonic activity is recorded in Hablerood catchment area and the lowest rate is recorded in Eivanaki (Galooshoot) catchment area, and Jajrood catchment area has revealed a medium rate of tectonic activities. The results showed that in catchments affected by the main faults of the area  such as Mosha, Emamzade Davood and Porkan faults in the northern area and Hesarbon, Eivanaki and Garmsar faults in the central and southern area, high tectonic activities were recorded which were also confirmed by field observations.

Abstract The extinction, adjustment and/or adaptation of flora and fauna have been affected by climate changes through environmental elements alteration. The results from the previous studies showed that there was a relation between domestication of wheat, genetic variation and paleo-climatic conditions. Wheat has been adapted to colder and severe winds climatic conditions with formation of small cell and changing in size and shape of seeds together with shortening and thickening of stem approximately 12500 years ago. The studies showed that wheat crop was planted in the Fertile Crescent region for the first time and then spread out in other geographical areas. Structural and behavioral characters of wheat crop were made in different climatic periods so that it was disappeared in some geographical areas and adapted to others with the environment. As extent of plant communities were changed during different climatic periods, some crops dead and some of them were adapted to the new conditions. To understand that how much climate change have affected on domestication and evolution  of wheat crop and the crop how much will be able for adaptation to future climate change, it needs to know about the domestication and evolution trend of wheat in different climatic periods. By identifying the relationship between climate and wheat morphology and genetic, It is possible to predict the future changes of the strategic plant under different scenarios of climate change. The highly adapted species can be selected on the basis of precipitation and temperature changes in the future. In addition, the suitable regions can be introduced for planting the crop.
Methods:
In this study, about 80 national and international papers in the field of wheat genetic variations has been studied since its inception of Gramineae family. The effects of climate changes on different species of wheat were investigated in various periods as well. With regards to the growth and development together with the adaptation of the crop in different regions and climates in the past, the suitable climate as well as location were detected for planting in the future.
 
Result:
Gramineae family has been evolved during the Cretaceous period 55 million years ago. Although, phytolithes found in dinosaur fossils showed  that  the plants have existed 66 million years ago (Payprnv, 2005). Cretaceous is the third period of the Mesozoic era after  Triassic and Jurassic in which occurred 145 to 65 million years ago and lasted seventy million years of the Cenozoic is the longest period. The area of broadleaf forest, grasses species and  Gramineae family increased in North Africa and the Fertile Crescent  in 110000 to 116000 years ago (Underhill et al., 2001). Wild Einkorn grains found in the Fertile Crescent has the precedence more than 12,500 years (Ren plentiful, 1979), but the grains of the domesticated type discovered in archaeological sites in Greece, Cyprus and Balkans of has the precedence of  9500 years old. Einkorn wheat was very important for early farmers in Central Europe (7000 years ago). The genetic studies on Einkorn wheat showed that it was grown in the basaltic foothills of the mountains of Karajadagh  in southeastern Turkey as a volunteer plants,  and settlements used the  grains and later to cultivate it (WAN-friendly, 1981). Emmer wheat domestication was one of the most important stages of its domestication. Emmer wheat of Tetraploid and is the ancestor of T. dicoccoides. Wild emmer wheat is AABB with T.uratu gene Which causes relent and fragility of  grains and the ear (Worrack and others, 1993). An accurate studies were not done about the domestication of wheat together with at what time epigenetic changes occurred in Einkorn and Emmer wild type in Iran. Research Results showed that the dominant food of Zagros residents was cereals (especially wheat) at 9000 years ago (Brvshky et al., 2016).
Discussion:
Man collected wild grains at least 20,000 years ago and knew that plants are grown better in a certain conditions. They were produced less yield or dead due to pests and disease at some years time. Recent finding related to results of survey of wild genes of agricultural products revealed that domestication of plant have been often took place in Asia more than 12,500 years ago (Salamís and others, 2002). Einkorn and emmer wheat, barley, peas, lentils, buffalo pea and flax were domesticated at the first time in the Fertile Crescent (Hillman, 1966). Einkorn  wheat Was the first variety which successfully cultivated. It was a diploid species that was domesticated in the Fertile Crescent more than 12,500 years ago. Although, the cultivation the wheat was stopped in 5500 years ago. As polyploidy species had more adaptation with warm climate conditions, People began to cultivate it. In addition, it was harvested easier than einkorn type and had softer Glume  as compared to einkorn one. Current wheat, hexaploid bread wheat (Triticum aestivum ssp. aestivum) are a conjunction between the emmer wheat tetraploid (emmer Triticum turgidum)and diploid species. It could be said that bread wheat in the nature does not wild ancestor of hexaploid and it is considered as a hybrid or transplant plant.
 
Conclusion:
The Climatic conditions in the Younger Dryas period caused the most metagenesis changes in wheat that cultivated by inhabitants of the Fertile Crescent. This period was a period of cold climate in Europe whose an ice age happened and agricultural practices was only in the lower latitudes such as areas located in southwest Asia, southern parts of the Mediterranean and southern parts of India and China. Wheat crop can reduce the transpiration surface area by forming small cells against dry conditions. From the middle East, wheat migrated China throughout the Silk Road and other transportation routes, southern parts of central China was old and drier than the Middle East. The southern China districts had a warm humid climate in 7,000 years ago, but there was a relatively cool and dry conditions 6300 years ago and the size of grains of wheat and rice were smaller and similar to its current state at the same time. The size of wheat seed was reduced in the 2000-5000 years ago; It could be said that climate change during the  Yangrdryas period has been effective on  domestication and increasing the power adaptation of wheat in different geographical areas.  However before that, wheat was cultivated for a long time but, it did not have the properties of domesticated wheat. Cold and dry climatic conditions in Yangrdryas (12,500 years ago) and dry climate in 5000-6000 years ago causes increasing the resistance of wheat and, created more morphological and metagenesis changes. According to the report (IPCC, 2007) warming of the Earth by 0.13 degrees Celsius per decade in the last 50 years is almost two times of the rate of  recent past 100 years. Temperature increase has been estimated 0.74 degrees Celsius in the last century. Wheat is sensitive to high temperature, but the sensitivity depends on several factors such as variety, ambient temperature in which corn growth and its growth stages. The experiments showed that temperature increase affected wheat growth, and this reduces the crop growth period and the crop yield and quality will be decreased, consequently. Warmer climatic conditions is effective in reduction of fertility, changes in size, crop seed shape and quality, and achievement of consistency with current climatic conditions for cereals  in low and middle latitudes. With the transferring of agricultural belts to high latitudes, although, there will be a desirable temperature conditions to grow wheat, factors including high humidity, poor soil organic matter, and low thickness of the soil are the most important issues that restrict the wheat cultivation. Moreover, the probability of the pests and fungus outbreak will be increased for cereals.

Abstract Introduction
Climate changes are the most important event on the Quaternary period and Playas are the climate changes legacy. Playas are legacies of the Quaternary climate changes and have the special position among of the geomorphological areas of Iran, especially in the dry areas. Terraces, alluvial fans sequences and coastlines movement are main evidences base-level changes during the Quaternary. Playas and lakes or generally inner craters have a key role in the climatic balance and ecological changes in the Quaternary, in their surrounding areas and always have been considered to determine past climates.
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Area location
Lut desert in Iran's southeastern is in the area of SISTAN and BALUCHESTAN and KERMAN provinces. Iran Yardang is formed in west of the central Lut Desert that is the unique example of the magnitude and extent. This lake is located in the South Lut located at in south-eastern Iran in the Yardangs range .
Materials and methods
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In this study, we have examined the geomorphological (lake terraces) and sedimentological (lake sediments) evidences for reviewing the range of Lut lake. It has used the documents and library materials (including books, Persian and English articles and dissertations), video sources (including geological maps, ETM satellite sensor Landsat imagery, TM and Digital Elevation Model SRTM 90 meters and Dem 10 meters), Visit and sampling of the area (Terraces and lake levels of area were visiting and terraces were sampled to approve the lake sediments) and as well as are used laboratory operations. In this research, they have been observed terraces in the northeast areas of Yardang by field studies and sediment sampling was conducted for confirm sedimentology date for the marginal area of the past lake. Also with the passage of air in the Southeast region is detected terraces in the location and similar terraces in the eastern regions are determined by using satellite imagery and digital elevation model. Based on height data obtained from the terraces that they are the lake water level in the Quaternary it was rebuilt lake range for Lute for that was specified the lake dewatering range in prior periods and it was determined the extent of the lake. Also with tests on sediment samples and eventually the calculation of the indices due to sedimentary indexs and examination of sediments features with an average small to medium sandy sediments, sandy sediment conditions has been approved in the lake margins in Quaternary.
 
Results and discussion
Checking the Lut Desert terraces indicates that the terraces around this plains have not similar height But according to study, 330 350 404 meters depth by using of a Digital Elevation Model and compliance with satellite images having best match with the lake terraces of around the hole and based on these curves, the lake border is designated at different phases of advance and retreat in the area. Finally, we researches on the sediments of the lake terraces in the area and based on the particle average depends on source type of deposition, transport factor type and deposition conditions and sediments and indexes shows energy conditions in layers. Should be stated that this terraces confirms the lake-margin sediments conditions with an average of small to medium sandy survey.
 
Conclusion
Evidence indicates that there have been a relatively shallow lake in the past and low energy environment and it is affected by evaporation and drying conditions alternatively. As well as different levels of terraces with different heights shows the advance and retreat phases of the lake.

Abstract Improvement of our understanding in the environmental and geomorphological changes’ effects on marshes andisolated waters is a critical step to address issues related to continental marshes and their responses to thesechanges. Also, sedimentological studies are proper tools to interpret the evolution of sedimentary environment(Ward et al,1998). Additionally, to assess the ecological impact of contamination to the environment, it is vitally important tounderstand the full extent and the level of pollution into the background in the area.Regarding its capabilities in providing goods, marshes environments are classified as the most precious ecosystemson earth(Moreno,2015). Considering the effects of climate changes and human interferences, today the future ofthese important landforms and ecosystems seems to be at risk and it may cause possibly irreparabletransformations(Murray et al,2011). Also characterizing of the composition and the sedimentology of surfacesediments is vital not only from geochemical point of view, but also from an environmental perspective. Thusvariations in mineral compositions, trace elements and lithogenic components should be considered as valuabletools to find out the possible sediment sources and physico-chemicalprocess affecting the geological records) Bernardez,2012).Nowadays, Eynak marsh is strictly isolated from any riverine and oceanic sediment input. Anthropogenic effects (as an instance intense construction operation, sewage input to marsh and etc.) likely contribute to changing the circumstances and its natural habitat. Despite the importance of this area, there is no worthy investigation devoted to the study of, geophysical, mineralogical and sedimentological signature of Eynak marsh. This investigation could be more momentous if we spot contamination of sewage entrance from the urban areas and also underground linking to GoharRood River. It is noteworthy that, GoharRood by itself is a fully contaminated river transporting sewage from upstream.
Materials and methods
Eynak Marsh is located in west of the Rasht city, North of the Guilanprovince.Eynak naming comes from Persian translation of word Glasses, because of similarity between glasses and aerial photos of EynakMarsh.Eynak Marsh is located on Gohar Rood river near by at the urban area with dimensions of more than two thousand meters in length and more than 150 meters in width.
To study the sedimentary environment of the Eynak Marsh, 44surface sediment samples were collected using of a sediment sampling device (Van Ween Grab). Afterward, on the lab, samples were dried at 70˚ and dried bulk sediment was sieved to separate various fractionsusing wet sieving (based on standard test ASTM for determining average grain size). Grain size analysis of the 44 surficial sediment samples performed by Analysette 19 wet sieving instrument. Therefore, samples grouped into mud, sand and gravel fraction according to Udden and Wentworth. A detailed description of grain size <63 μm fractions executed by Laser Particle Seizer (model analysette 22).Collected samples analyzed for granolometery and it calculated same statistical parameters such as mean, sorting, skewness, and  kurtosis. Moreover, X-Ray diffractions in 44 sediment samples in the area have been performed using an automaticpowder EQUINOX 3000 X-ray diffractometer.Geophysical studies done using of Geoelectric and ground penetration radar techniques to determine depth and material of surrounding sediments and checking for sub-surface discontinuities existence and connection of this marsh with Gohar Rood River.
Results and discussion
mineralogicaland physical characteristics of the sediments in Eynak marsh can be influenced by rock assemblages inupstream such as basaltic-andesitic lava, dark grey limestone, slate and Arkozic sandstone which has been subjectedinto weathering, eroded and transported to downstream. In fact, due to terrestrial sources of sediments inEynak marsh, it is characterized by similar mineralogical and physical features.According to grading studies, 13 sedimentary types existed in surface sediments including: Gravelly Mud,Muddy Gravel, Gravelly Sand, Muddy Sandy Gravel, Gravelly Muddy Sand, Muddy Sand with a Little Gravel,Sandy Mud with a Little Gravel, Mud with a Little Gravel, Silty Sand, Muddy Sand, Sandy silt, Silt, Sandy Mud.Various statistical parameters of Eynak marsh sediments computed. Mean grain size: Different values obtained for textural statistical parameters varying from minimum 1.5 to maximum6.6, i.e. thusit falls between coarse sand and medium silt. Sorting: In the study area sedimentsranges in 3 sorts: poorly sorted,very poorly sorted, and moderately sorted. The closer to GoharRood, the sorting number increases and sedimentspoorly sorted. Skewness: In the present study skewness values ranges −0.43 to 0.68 with an average−0.02 representsfive sorts: strongly fine skewed, fine skewed, near symmetrical, coarse skewed, strongly coarseskewed.Kurtosis: Many curves designated to minute Kurtosis and it varies from platykurtic to mesokurtic. Also thevalues are among 0.5 to 2 with an average of 0.99. Scatter plot with mean, standard deviation and skewness can be used successfully for the distinction of the sedimentaryenvironments, always using a large number of samples for each sedimentary body sampled(Martins,1997).The scatter diagram proved that the distribution of grains belongs to fluvial and riverinesediments.
Conclusion
The results of granolometery shows thirteen dispositional types in the region and major component mineral were quartz, calcite,feldspar, and mica and minor mineral were pyroxene, evaporates along with some heavy minerals.bad sorting in Eynak Marsh shows that the source of sediments near the basin pass through a short transportation route. Skewness generally seen as near symmetrical shows the abundance of coarse grains in an energetic environment, where as kurtosis is generally seen as platykurtic and mesokurtic. The essence is revealed that between the Eynak Marsh and the Gohar Rood River exists a high resistive anomaly due to Rasht fault on the sidelines of  Marsh and change the kind of sediments in this area. Therefore, sedimentary statistical parameters and geophysical studies show that the Eynak Marsh Tributary of Gohar Rood Riverwere cut-off By  Rashtfault and it has shaped in current form.

Abstract Soil is regarded as one of the natural slow biodegradable source which plays an important role in the cycle of mineral and organic elements. As a dynamic ecosystem, it provides the life for big and small creatures, so removing its pollution is of considerable attention. The pollution of heavy metals not only affects directly the physical and chemical features of soil and reduces biological activities and access to nutrition materials in soil, but also is considered as a serious danger for human health. In fact, they can enter food chain or penetrate underground water sources.Iran is one of the oil-rich countries in the world in which high amount of oil is extracted in southern regions and refined in other places yearly. Once oil is extracted, transmitted and refined, its release in the soil causes pollution. A group of soil pollutant sources is related to oil discoveries, production, saving, transmission, distribution and final burial of wastes. If these industries are pollutants, they will cause dangers. The increase of soil pollution by heavy metals has led to a lot of research.
2-Materials and methods:Kermanshah province is located to the west of Iran sharing borders with Lorestan, Kurdistan, Ilam and Hamedan and an international border with Iraq. Its geographical coordinate is between (33^˚37^̕to 35^˚17̕) northern longitude and (45^˚20^̕ to 48^˚01̕) eastern longitude. Since Kermanshah Refinery is built on alluvial terraces, fans of new low foothills and Inceptisols and Vertisols,15 samples of surrounded soil were collected by an iron shovel from the depth of 15 to 25 cm. ICP-MS method, were used to analyze and determine the density of heavy elements in of the samples. Grinded to the sizes less than 4 mm by crusher, the samples were become powder to the size of 75 microns (200 mesh) by disc mill. Weighing the samples by Teflon pipes in digest 4 acid, hydrochloric, perchloric, nitric and choloridric acid were added to the samples equally. All samples were kept in Hot Box case. After complete digest operations, the samples were cold in the environment temperature and achieved volume by distilled water.
3-Results and discussion:The findings from geo-accumulation index shows that the intensity of Refinery soil is classified in the range of no pollution to average regarding chromium and nickel. Besides, enrichment index indicates average enrichment for cadmium (station 14), copper (stations 13, 11, 2 and 14), lead (stations 6 and 13), zinc (stations 11, 6, 2, and 13) and chromium (the stations from 6 to 15). In addition, pollution bar index of chromium, copper, nickel, zinc and lead is more than 1 proving the inappropriate soil quality and soil pollution of the region. However, chromium has the most considerable value, 2/75. Average value of EF is less than 2 for arsenic, cobalt and vanadium proving that the region does not show enrichment for the aforesaid elements. Enrichment index values for cadmium, chromium, copper, nickel, lead and zinc are between 2 to 5 indicating average enrichment of these samples than other metals. Since enrichment element for these sample are higher than 2, they have anthropogenic source.
 According to Pearson correlation coefficient, there is a high correlation between nickel and chromium, scandium and cobalt, vanadium and chromium, and zinc and copper and lead indicating the equal source or similar geochemical behavior of the elements toward each other. Since vanadium is considered as one the oil pollution indices, it can be concluded that high pollution of this element and chromium around the region comes from petroleum.
4- Conclusion:The findings from the present study shows that soil surrounded Kermanshah Refinery are polluted to some elements. According to the values of geoaccumulation in the studying area, elements nickel and chromium have pollution. The finding from enrichment factor indicates the average enrichment of the region soil by chromium and lead. Besides, enrichment factor higher than 2 for lead and copper proves anthropogenic interference factors in the region pollution to them. The results from pollution bar for chromium, nickel, zinc, copper and lead is more than 1 indicating soil pollution to these metals. Pearson correlation coefficient reveals that there is a high correlation among vanadium, cobalt, chromium, and nickel proving same origin. Making zoning map of heavy metal density in the region soil demonstrates that high density of the elements in some stations is related to petroleum producing installations and storage tank. Cluster analysis shows the division of the elements into 7 clusters. Besides, the elements with structural relationship are related in next subcategories. Clusters 6 and 7 together indicate the same origin for these elements. Since vanadium is derived from oil compound, it can be concluded that chromium and nickel pollution have the same pollution origin with oil compounds. Factor analysis introduces 3 main factors in which the first factor with total 40/1% of total variance is the most effective factor in density of the soil elements. This factor has a high positive correlation with Sc, V, Ni, Cr, and Co proving the same density origin with petroleum compound.
 

Abstract Before the advent of Holocene, the subsistence of all hominins was hunting and gathering. Different biomes have been occupied by Homo sapiens during late Pleistocene. Due to the fact that subsistence-related activities in a given patch are aimed at adapting to a pack of specific characteristics, the ways to reach this goal could be called adaptive strategies. There is ample evidence supporting the assumption that inter-biome (or inter-patch) differences had had dramatic impacts on hunter-gatherers’ various ways of life, generally speaking, and the dependence of Pleistocene foragers upon local environmental characteristics was heavier than horticulturalists or even hunter-gatherers of later periods.
            Some models in the framework of human behavioral ecology have been developed in order to grasp different foragers’ behaviors (decision making). These models are based upon optimality for the most part. Foragers could decide which way to choose to acquire a resource among other options, each with its costs and returns. The optimal way is the one with the least cost and the most benefit (return). Finally, foraging optimally would increase individual or group fitness.
MATHERIALS AND METHODS
For investigating on subsistence strategies of Pleistocene hunter-gatherers, a framework should be constructed based upon anthropological and evolutionary ecological models and then, in this light, archaeological finds could be analyzed and explained. Generalized models, built upon the studies of contemporary hunter-gatherer bands from the ecological viewpoint are analyzed in this paper. The degree to which these models are consistent with data recovered from Pleistocene archaeological sites is equivocal and under scrutiny. To answer such questions more and more archaeological study is needed. In this paper, bibliographic analysis has adopted to assess the relationship between foragers and the natural environment. 
FINDS
Statistical works of researches on contemporary hunter-gatherers and some inadequate archaeological evidence imply that foragers’ subsistence-related activities have been regularly related to the environmental parameters with a good accuracy. Pioneers such as Binford have pointed at insolation, effective temperature, and the distribution of solar heat as the ultimate causes (and the most important one) of diversity in biomes and consequently, in foragers’ subsistence; but one should keep in mind that absorbing more solar heat, higher temperatures, and higher net primary productivity (NPP) will not necessarily result in more accessible food to the human foragers, especially the prehistoric ones.In biomes with higher NPP, such as tropical rainforests, a great deal of energy will be invested in structural maintenance (tree trunks) and the capture of sunlight (taller and taller trunks), therefore, the food available to foragers is not that much; whereas in some regions with lower NPP (e.g. African savannah) more energy will be dedicated to reproductive or storage organs of plants which are widely edible for human foragers. Based on this, human foragers tended to live on the edges of dense forests (ecotones) and not the jungles themselves. Therefore, estimation of the availability of food in different biomes is not possible solely based on NPP comparisons.
            One of the most important aspects of foragers’ life is mobility. It is as much important as that it can explain the variability in archaeological sites to some degree. Based on bibliographic work in this paper, mobility is dependent upon the availability and distribution of resources among other things. For instance, when resources are evenly distributed in space, high residential mobility is practiced in order to decrease the risks associated with local depletion of resources. As a result, archaeological sites associated with foragers with high residential mobility should be smaller and less complex (less intra-site variability) compared to collectors’ settlements (high logistical mobility). On the contrary, when resources are clumped (highly unpredictable environments), logistical mobility would be higher and consequently, associated archaeological sites would be different from the first example. These are some ecological rationales behind the variabilities observed among Pleistocene archaeological sites.                
DISCUSSION AND CONCLUSION
It seems that at least part of the differences which have been observed among the archaeological remains of the Pleistocene settlements around the globe (e.g. differences in size, complexity, faunal remains, and artifacts) could be interpreted in the light of different subsistence strategies. For instance, logistical mobility results in archaeological finds and associations which are most probably different from archaeological sites belong to foragers with residential mobility. But one should keep in mind that this variability has an ultimate cause which is characteristics of biomes (such as climatic regimes, the distribution and abundance of critical resources, and as such). In other words, optimal strategy in landscape A differs from landscape B mostly due to the environmental characteristics. In addition, in unpredictable environments (spatially and temporally), optimal strategy may change during time, with other things held constant (e.g. ideology, or history-related inertia). 
            Finally, it should be noted that all models discussed in the paper are developed just based on physical properties of environments. Therefore, they cannot explain all the variabilities observed among foragers and their associated archaeological sites. Things such as ideology and worldviews, inertia of history, sexual selection, individual decisions and so on can play vital roles in the formation of foragers’ strategies and then, their archaeological remains.