بازسازی شرایط محیطی محوطه‌های باستانی با استفاده از آنالیزهای ژئوشیمی مطالعه موردی: تل ملیان (انشان)، استان فارس

مطالعات زمین‌باستان‌شناسی بیان‌کننده روابط بین انسان‌های گذشته با محیط و تاثیر هر یک از این دو بر یک‌دیگر است. در این مطالعه، با استفاده از داده‌های رسوب‌شناسی و ژئوشیمی، به بازسازی تغییرات محیطی در محوطه باستانی تل ملیان استان فارس پرداخته شد. از مجموع 22 گمانه حفرشده در داخل و اطراف تل ملیان، تعداد 140 نمونه خاک بر اساس تغییر لایه برداشته شد. با توجه به تغییرات لایه‌ها، تعداد 72 نمونه برای آنالیز xrf انتخاب شد. بر اساس نتایج این تحقیق، بافت خاک محدوده عمدتاً ریزدانه است و در برخی گمانه‌ها، مانند گمانه 18 و 9، رسوبات درشت‌دانه مربوط به رسوبات رودخانه‌ای دیده می‌شود. جهت رسوب‌گذاری در گمانه 18 غربی‌ شمال‌شرقی و در گمانه 9 غربی‌ شرقی است. بیشترین شواهد و بافت سیلابی در محدوده گمانه 18 و 9 در بخش‌های شمال‌شرقی محوطه و بخش‌های جنوبی محوطه مشاهده شد. بین لایه‌های سیلابی آثار و بقایای سفال نیز به دست آمد که موید آن است که در زمان فعالیت شبکه‌های زهکشی، در تل ملیان، سکونت وجود داشته است. نتایج داده‌های xrf در گمانه 18، به منزله شاخص‌ترین گمانه طبیعی در محوطه تل ملیان، پنچ روند افزایش و کاهش رطوبت را نشان می‌دهد.

Reconstruction of the Paleo-Environmental Ancient Settlement Using geochemistry AnalysisCase study: Tal-e Malyan (Anshan) of Fars Province

IntroductionGeoarchaeology is defined as the application of geological concepts and methods to solve archaeological research questions (Butzer, 1971, 1982; Waters, 1992; Pollard, 1999; Goldberg and Macphail, 2006).Urban geoarchaeology is focused on site accumulation, collapse, weathering and erosion, These may document settlement growth and decay, as well as environmental history, posing a multidisciplinary challenge of interactive and fluctuating processes (Butzer et al., 2013). The purpose of this research is to reconstruct paleoenvironment of the area to investigate the rich culture in a place as capital of Ilam Majesty and their relations of the people with their natural environment. Materials and methodsIn a sampling of the ancient site of Tale Malyan (Anshan), Fars province, for reconstruction of its environmental conditions, we have collected a total of 140 samples from 22 transects. The sampling was based on the changes in layer and color of the deposits, in every 20 cm in cases with gradual color change. To determine the texture of the sediments, the samples were dried at 105 ° C for one night. The particle size larger than 2 mm was considered to separate gravel and sand using a Shaker machine. Smaller particles were also read 9 times for separation of silt and clay and sand using hydrometric and ASTM Standards. The amount of organic matter in the sediments (1020 g) was determined by thermal loss method. The samples were initially dried at 105 ° C and then weighed and heated in a furnace at 450 ° C for 4.5 hours to calculate their weight and organic matter. Soil chemistry measurements were performed using distilled water and soil sample. To measure soil acidity and salinity, 30 grams of each sample was taken. After preparation, the samples were measured by pH meter. In this study, for XRF analysis 72 samples were delivered to the laboratory of the Institute for Conservation and Restoration of Historical and Cultural Works. The elements were measured using Xray Fluorescence Spectroscopy Model 8420.The study area is located in Fars Province, 46 km from northwest Shiraz. The Ilam civilization had two capital settlements in south and southwest parts of Iran, Shoosh in Khuzestan and Anshan in Fars. The Anshan was the greatest urban center, more than 200 hectares in area, with a population of 16000 people in Beyza plain. The Tale Malyan is located in N and E. Kor River is the most essential hydrographic network in the area. Results and discussionAccording to the results of the study, the soil texture is mostly finegrained and in some transects, such as 18 and 9, it is mainly composed of coarsegrained sediments related to river deposits. The orientation of the deposition in transect 18 is WestNortheast and in transect 9 is WestEast. Most of the flooding evidence and texture were observed in transects 18 and 9 in the northeast and southern parts of the area. Among the flood deposits and debris, we identified evidence of pottery confirming that there were settlements in Tale Malyan at the time of drainage, but later they reached their final extent.According to the results of the oxidationreduction diagram, the natural and cultural samples are mainly classified into three groups of hydromorphic soils, calcareous soils and sodium soils. The superiority of the hydromorphic soils indicates that the Tale Malyan (Anshan) site has been affected seasonally by groundwater. In general, transects on the east side of the site are more affected by groundwater and this can be testified by the light gray color of the sediments. ConclusionIn this study, using physical and chemical properties, we reconstructed environmental conditions of Tale Malyan (Anshan) area. Given the location of the site on the plain and the activity of drainage networks originating from the western highlands, the area has always been affected by the fluvial processes. Based on the texture characteristics, the drainage network in transect 18 is located in northeast of the area and the more recent drainage is located in the transect 9 in northeast. The northern part of the drainage network appears to be older and deposited in the lower layers where fluvial sediments were deposited in a shallow lake environment, in northeast part. This claim can be affirmed by the existence of light gray sediments with ammonites and bivalve layers, and the absence of cultural layers in the eastern parts. According to archaeological experts, the northern part of the site was likely settlement for nomadic tribes and the highlands of the southern areas of the region were perennial settlement. The drainage network in the southern part next to the south wall indicates newer fluvial sedimentation with good sorting that can be attributed to the inner channel environment. The sedimentation of this transect represents a general westerneastern orientation consistent with the overall pattern of drainage network on surface of the site.