بر اساس رسوب شناسی محیطی محوطه مافین آباد اسلامشهر

محوطه باستانی مافین‌آباد، در بخش مرکزی اسلامشهر و 3 کیلومتری جنوب روستای مافین‌آباد در استان تهران واقع است. این محوطه در سال‌های 1384 و 1385 به سرپرستی احمد چایچی ‌امیرخیز مورد بررسی و کاوش قرار گرفته است. همچنین، با حفر چند گود و گمانه پیرامون آن، رسوب‌شناسی محیطی شده است. سفال‌های مافین‌آباد عمدتاً هم‌افق با دوره‌های سیلک ii تا iii45هستند؛ اما، تعداد بسیار اندکی سفال سیلک iii67b نیز در محوطه مزبور یافت شده‌ است. بر طبق بررسی‌‌های رسوب‌شناختی، لایه‌ای رسوبی روی یک لایه خاک خاکستری دارای سفال‌های سیلک iii45را پوشانده است که احتمالاً گویای طغیان رودخانه باستانی نزدیک این محوطه است. پژوهش‌های دیرین‌اقلیم نشان می‌دهند که باوجود شرایط کلی بهینه اقلیمی طی هولوسن میانه در مناطق تحت تسلط بادهای غربی در غرب آسیا، اما رویدادهای خشکی طی هزاره چهارم ق.م رخ داده‌اند. این تغییرات اقلیمی ناگهانی، احتمالاً با رویدادهای آب‌وهوایی حدّی مانند خشکسالی‌های شدید و بارش‌های سیل‌آسا همراه بوده است، به طوری که طغیان رودخانه‌ها و جاری‌شدن سیلاب‌های عظیم در دشت‌ها و مخروط‌افکنه‌ها را در پی داشته است. گسستگی استقرار در محوطه‌های مس‌سنگی دشت تهران در اواخر دوره سیلک iii45 و روند کاهشی استقرارگاه‌های هم‌افق با سیلک iii67b و iv‌ و در تعقیب آن، افول عصر مفرغ در شمال ایران مرکزی، می‌تواند موید تغییرات اقلیمی اواخر عصر هولوسن میانه باشد.

Study on the Effects of the MidHolocene Climatic Changes onSialk III Societies in North Central Iran Based on Environmental Sedimentology of Mafin Abad, Islamshahr

The archaeological site of Mafin Abad, located in the central part of Islamshahr city and 3 Km to the south of Mafin Abad village, was excavated under the supervision of Ahmad Chaychi Amirkhiz in two seasons in 2005 and 2006 (Maps 12). Moreover, they have dug some trenches around the site for environmental sedimentology. Findings concerning prehistoric pottery in Mafin Abad are contemporary with cultural periods of Sialk II to Sialk III45. However, a few pieces of pottery belonging to Sialk III67b are found as well. Sedimentological data shows that a layer of dense sedimentary soil, on a grey and black layer, is covered by Sialk III45 pottery, which suggests flood events of an ancient river near the site. Mafin Abad had probably changed to a basin catchment for a relatively long time. Paleoclimate studies show that despite the overall optimum climatic conditions during the MidHolocene in the westerlydominated regions in West Asia, this period is punctuated by episodic dry spells, particularly during the fourth millennium BC. Such abrupt climate variability has probably been accompanied by extreme weather events, such as severe droughts and torrential rains which have potentially led to river overflows and massive floodings in the plains and alluvial fans. Detachments in habitats of the Tehran Plain in the late Sialk III45 period and the reduction of settlements in Sialk III67b and Sialk IV periods, and then, the cultural decline of the Bronze Age in North Central Iran, may be associated with the climate changes during the latter half of the MidHolocene. Due to its special geographical location, the effect of the air circulation system, subtropical high pressure, and other factors, Iran generally has a semiarid to the arid climate and a semidesert to desert nature. The cultural region of North Central Iran overlaps with two large basins of the Salt Lake and the western part of the Central Desert. Most of the prehistoric sites belong to the Salt Lake basin. In this part, several subbasins are resulting from the permanent rivers of Jajroud, Karaj, Qarachay, and Qomroud. The mentioned rivers and their branches have formed the main pattern of human settlements since the Neolithic period in the cultural region, because these human societies needed sufficient water resources for permanent settlement and agriculture and animal husbandry, as well as industrial activities and, finally, the formation of government and civilization. Climatic changes have had devastating environmental effects, disrupting the development and cultural transformation of ancient societies; Severe hurricanes, heavy rainfall, severe prolonged droughts, heat waves, and cold spells are some of the outcomes of climate change. Climate change in arid and vulnerable regions such as North Central Iran has had dire consequences for waterbased human communities. The archaeological site of Mafin Abad, located in the central part of Islamshahr city and 3 km to the south of Mafin Abad village, was excavated under the supervision of Ahmad Chaychi Amirkhiz in 2005 and 2006. Prehistoric pottery found from the layers of Tepe Mafin Abad was contemporary with cultural periods of Sialk II to Sialk III45. Also, a few pieces of pottery belonging to Sialk III67b were found on the surface. it is worth mentioning that the area of this site at the time of the excavations was 5.5 hectares, which was one of the largest settlements in North Central Iran in the Chalcolithic Age. During the excavations, six trenches were also excavated for environmental sedimentology around Tepe Mafin Abad called A to F. The A to C trenches were dug in the western part of the hill, side by side, along the northwest, at a distance of approximately 10 meters from each other. Also, Trench D was excavated in the southwest, Trench E in the south, and Trench F in the southeast of the site. The main question of this study was about how the environmental changes in this area in the chalcolithic period. We also sought to answer the questions of whether climatic events and natural hazards contributed to the decline of the prehistoric cultures of North Central Iran? What were the climatic conditions of the Chalcolithic Age (42003000 BC) like? This research is based on environmental sedimentology studies of the prehistoric site of Mafin Abad, Islamshahr (Figurs. 12). The stratigraphic report of each of the excavated sedimentary trenches along with the features and contents of each layer are presented in full. Also, to analyze the findings, archaeological information of the Chalcolithic Age of North Central Iran and paleoclimate research of Greenland (GISP2), Iran, and neighboring regions have been examined. The Middle Holocene covers approximately 8200 to 4200 years ago. This period in the cultural region of North Central Iran includes the cultural periods of Sialk I, II, III, and IV. Although in the first half of the Middle Holocene, in general, warm climatic conditions (in different areas with a decrease or increase in humidity) prevailed, but from about the beginning of the fourth millennium to the second half of the third millennium BC, frequently, abrupt climate change has occurred, causing severe droughts or torrential rains in various regions. Floodbased sedimentary strata in the ancient cities of Ur, Shurupak, and Kish in Mesopotamia from the midfourth millennium BC to the early third millennium BC may indicate the occurrence of climatic hazards associated with climate change.