جستجوی مقالات مرتبط با کلیدواژه "پلیستوسن" در نشریات گروه "زمین شناسی"

Qaleh Kurd cave is located in the village of the same name in the vicinity of Hesar Valiasr village, Avaj city, Qazvin province. This cave is located on the route between Zagros and Iranian Central Plateau and along one of the proposed corridors of scattered human groups in the Iranian Plateau (Vahdati Nasab et al., 2013; Dennell, 2020; Shoaee et al., 2021). The first archaeological study in the cave was conducted in 2013, in which a small surface collection of 35 stone tools on the surface was studied and attributed to the Middle Paleolithic era (Soleimani and Ali Beigi, 2018).With the initial investigation of the walls of the pits caused by unauthorized excavations and the presence of cultural materials and animal remains in the cave, the first idea about the possibility of exploring this area was formed. The first examination in Qaleh Kurd cave was conducted in 2017 by some of the authors (HVN & GB). Consequently, the joint Iran-France mission under the supervision of (Vahdati Nasab, Berillon and Hashemi) conducted three archaeological field mission in there (2018, 2019, 2022). It is worth mentioning that here we only present data collected during the first two seasons.Some of the major goals of conducting field missions in Qaleh Kurd are: Investigating the Paleolithic deposits, how the site was formed, comparing lithic industries with other Middle Paleolithic sites of Iran, reconstructing the diet of cave dwellers and trying to obtain human remains. The purpose of this article is to describe the techno-typological aspects of lithic collections recovered from 2018 and 2019 missions and to compare it with the lithic industries of Zagros, and the sites from the Iranian Central Plateau.

The stratigraphy of the trench 1 wall indicates the existence of two distinct sequences, Holocene and Pleistocene, and the identification of 25 stratigraphic units (1 to 9 related to the Holocene and 10 to 25 related to the Pleistocene). The preliminary results of dating samples taken from 30 cm from the beginning of the Pleistocene layer in Trench 1 indicate an age beyond the range of carbon-14 dating (43,500 years ago). Therefore, in the continuation of the research, the ESR method was used for the dating of cultural materials (especially animal teeth). It is worth mentioning that at the time of writing this article, the above-mentioned chronology is being finalized and the preliminary results indicate an age of more than 300.000 BP for the Pleistocene deposits, which will soon be published in separate research.The subject of the present research includes the stone artifacts obtained from the exploration of the first and second seasons. In total, 1257 stone artifacts were obtained from excavations in trenches 1 and 3. In this study, the data obtained from Trench 1, the largest explored trench, is presented. The excavation dimensions in trench 1 were 1.2966 square meters in the first season and 6.195 square meters in the second season.Quantitative characteristics, typological information and technology of tools have been recorded and studied. In a general classification, stone artifacts include tools, debitage, core and core fragments, and debris. According to the stratigraphic information of trench 1, the Pleistocene sequence of Qaleh Kurd is divided into fifteen sedimentological units and five successive archaeological subdivisions. The division of archaeological periods is based on sedimentological studies, changes in the density of stone artifacts and animal remains, and data distribution in depth.The first period or the late period (QK 1) starts from about -50 to -80 cm (Z) of trench 1 and includes sedimentological units 12 and 11. Unit 11 in the eastern wall of Trench 1 consists of gravelly sand silt with pebbles and flat unlayered gravels with charcoal remains. Unit 12 also includes sandy silt with a number of calcite gravels, a matrix with low compression and more compactness. QK 2, or the middle period, starts from the depth of -80 and continues to the depth of -105. This course is in line with unit 13. This unit in the south wall of Trench 1 has a light brown color and debris pieces and quiet dynamics. Unit 13 on the eastern wall of Trench 1 has sand-silt with many pebbles and flat calcite debris. QK 3 starts from the depth of -105 and continues to the depth of -130. This course includes units 14, 15 and 16. Unit 14 in the south wall of Trench 1 consists of clayey silt with gravel and is brown in color. Unit 15 includes organic silt and unit 16 includes silt (clay). In Unit 16, we see gravel, calcite nodules and ancient soil. On the eastern wall of Trench 1, silt with gravel in unit 14 and silt with organic clay in units 15 and 16 are evident.The raw materials of Qaleh Kurd stone artifacts are diverse, including limestone rich in silica, jasper, chert group, volcanic stones such as basalt, a limited number of marbles, radiolarite, clay and quartzite. The most used raw materials in all the phases of Qaleh Kurd are siliceous stones rich in lime, so that in the first period 22.5%, in the second period 20.5% and in the third period 32.1% of artifacts are built on limestone.

In Qaleh Kurd lithic complex, the cores are very limited and it seems that the initial steps of chipping were done outside the area. A variety of raw materials have been used in this collection, and the three aforementioned Qaleh Kurd periods show different abundances in the use of raw materials. In this area, sidescrapers are the most abundant type of tools, after that we are faced with a significant abundance of points and convergent scrapers. The studies conducted on the quantitative characteristics, typological and technological indicators of the stone artifacts showed that in terms of dimensions and quantitative characteristics, the lithics of the first, second and third periods of the cave demonstrate no difference, but the dimensions of the blades are somewhat different from each other. The comparison of the abundance of raw materials, extractions, platform typologies, and Levallois technique between the periods shows the difference of the third period from other periods to some extent. In this period, we see a high accumulation of lithics compared to other periods, this can be due to the intensity of settlement in this period of the site.The results of the comparison of Qaleh Kurd stone artifacts with other Middle Paleolithic sites show that Qaleh Kurd cave in the extent of using the Levallois technique, the abundance of scrapers, especially sidescrapers, the abundance of points, especially the Mousterian points, the faint presence of notch/denticulates and, the intensity of retouching and the abundance of flaked base debitages show a closer proximity to the Zagros sites.

The study of loess sediments and loess-derived soils, which cover approximately 10% of the Earth's surface, is of considerable importance because of their potential to provide information on the paleoenvironment, particularly during the Quaternary. The northeastern region of Iran, with its unique climatic archive, is of significant importance as a repository of Quaternary period deposits, attracting much attention from Iranian and international scientists in recent decades. Considering that soil forms in response to interactions among the lithosphere, hydrosphere, and atmosphere, it potentially contains physical, biological, and chemical environmental information at the time of its formation. The process of becoming loess sediments into paleosol depends on various factors such as vegetation, weather, topography, microbial activity, and time, so paleosols have the potential to restore the paleoenvironment by maintaining the effect of these factors. Therefore, studying soils derived from loess can enhance our knowledge and understanding of past climatic conditions in the region and the world. Studying undistributed soils using microscopic techniques can provide valuable information for understanding the environmental and climatic conditions during the formation of derived soils from loess (paleosols). One of the quantitative methods for studying micromorphology samples is the use of indices such as MISECA, which indicate the degree of paleosol evolution. By using this index, we can have an approximate estimation of paleoprecipetation. The main aim of this research is to reconstruct the precipitation amount during the formation of late Pleistocene paleosols in the eastern part of Golestan province, using micromorphological studies.

In order to conduct this research, after field visits, a profile of approximately 55 meters was excavated to examine the identified loess-palaeosol sequences. Then, undisturbed samples were obtained from each horizon to prepare thin sections, and the samples were impregnated under vacuum conditions using a combination of resin, acetone, and catalyst. After the samples hardened, a thin section was cut from them and affixed to a glass slide. The thin sections were then polished using sandpaper until a thickness of 30 microns was achieved. The prepared thin sections were studied using a polarizing microscope.

Micromorphological analysis of the samples revealed that the presence of horizons rich in calcium carbonate and clay in well-developed paleosols has a significant relationship with increased precipitation.  Micromorphological studies showed that the coarse to fine (C/F) relative distributed results showed that the amount of it in loess horizons and weakly developed paleosols are 4/6 or 3/7 but this ratio in moderately and well-developed paleosols become smaller in comparison with loess horizons, indicating the weathering and leaching of primary minerals in loess sediments and their transformation into secondary minerals in paleosols. Furthermore, with increasing paleosol evolution, the microstructure of the samples changed from massive to subangular blocky and then to angular blocky. Therefore, the results of examined microstructure in the samples showed that it can be one of the important factors for identifying paleosols from loess horizons and paleoenvironment conditions. Based on the data obtained from the MISECA index, the degree of paleosol development ranged from weakly developed (MISECA index was smaller than 8) to well developed (MISECA index was bigger than 16). The estimated paleoprecipitation amount using this index showed that paleosols with weak development formed under climatic conditions with precipitation less than 500 mm per year, while paleosols with moderate and well developed formed under climatic conditions with average precipitation of 500 to 800 mm per year and more than 800 mm per year, respectively.

Considering that soils are formed as a result of interactions between the lithosphere, hydrosphere, and atmosphere, they potentially contain physical, biological, and chemical information about past environmental conditions. Therefore, by studying the Late Pleistocene loess-paleosol sequences in Golestan province, it is possible to reconstruct past climatic changes in northeastern Iran. The micromorphological investigation of the loess-paleosol sequence under study showed that the processes of transfer and deposition of clay and secondary calcium carbonate and the subsequent creation of horizons rich in clay and secondary calcium carbonate are among the most important pedogenic processes in well-developed soils. Micromorphology can be a useful tool for investigating the paleoclimate and paleoenvironments conditions during the formation time of paleosols. The results showed that the use of the MISECA index can be a valid and logical method for evaluating the degree of paleosol development.

Paleozoology of Yafteh and Kani Mikaiel caves in center and northwest of Zagros Mountains led to the identification of small mammal's assemblage. Taxonomic determination revealed inclusion of four orders of small mammals including: order Rodentia with families of Muridea, Cricetidae, Calomyscidae, Dipodidae; order Lagomorpha with two families of Ochotonidae and Leporidae; order Soricomorpha with family Talpidae, and order Carnivores with family Mustelidae. These remains were recovered after systematic excavation in these caves. Radiocarbon analysis of these remains showed the oldest sample belonged to Yafteh cave with 35,000 BP. and Pleistocene period, whereas, Kani Mikaiel cave covered the periods from lat Pleistocene (19,000 BP.) to Holocene (17, 00 BP.). Geochronology analysis of Kani Mikaiel sediments showed that the lower layers of this cave belonged to the last glacial age in Pleistocene which gradually has been replaced by the warm weather in Holocene period. With continuing of this weathering varying, faunal spectrum of Pleistocene and Holocene periods has been migrated in cold and warm phases or more spread. The aim of this research, are the study of small mammal remains of Yafteh and Kani Mikaiel caves in center and northwest of Zagros mountains and the research about the study of paleobiodiversity, paleoenvironment conditions and the evolution of microvertebrate on the Iranian plateau.