جستجوی مقالات مرتبط با کلیدواژه « mirak » در نشریات گروه « زمین شناسی »

Mirak (Semnan, Iran) is a Paleolithic site located in a dry floodplain near the northern edge of the Iranian Central Desert. The pedo-sedimentary successions of Mirak 8 are deposited from late Pleistocene to Late Holocene,. The chronological framework was established using optically stimulated luminescence (OSL) dating. The oldest studied units dating back to ~50 ± 3.0 ka. Within this stratigraphy, two distinct depositional environments are recognizable: Sequence I = alluvial floodplain deposits and Sequence II = calcareous aeolian deposits. The alluvial succession is represented by alternating horizons of poorly pedogenized bodies of loam, intercalated by splay sand interbeddings. The prehistorical remains occur exclusively at distinct limits and it is presumable that some prehistorical layers of Mirak are palimpsests resulted from repeated occupations. After ~1.2 ± 0.2 ka  an at least 3 ka long sedimentary hiatus cuts the sedimentary log of Mirak 8 and about 2m of aeolian assemblages take place over the discontinuity. This shift was clearly reflected in the laboratorial results. Results from XRD, FTIR, SEM and optical microscopy analyses, show very minor differences in mineralogy for the entire record regardless of the type of depositional regime and this we suggests a local and most probably polygenetic source for the deposits under study. Subsequent to deposition, both alluvial and aeolian accumulations were subjected to different extents of pedogenesis and thus developed pedogenic features characteristic of Entisols and calcareous, gypsiferous Aridisols (Bk, By). Varying iron content and different oxygenizing conditions between the two sequences are presumably relatable to higher ground water level and Fe-reducing conditions especially for the units deposited prior to ~28 ± 2 ka BP (OSL) and generally adverse conditions for the Holocene units.

 The area of study in this paper is located at the Northern fringes of Iranian Central Desert (NICD). Regarding its vast size, only the Paleolithic sites located in modern Semnan province are included in this paper. These sites are Mirak, Delazian, Soufi Abad, and Chah-e Jam, containing evidence of human presence during the Last Glacial Cycle (LGC; circa. 116-11.5 kya). The information surrounding the evolution of cultures in the Central Plateau of Iran during the Late Pleistocene is meagre. Moreover, its climatic-environmental fluctuations have not been studied throughout the mentioned stage. Therefore, running an investigation into data recovered from the Paleolithic sites have not been possible in the absence of climatic information so far. This paper, written based on a couple of field expeditions conducted in the NICD, is one of the first attempts to analyze the Paleolithic archaeological finds based on the Pleistocene climatic-environmental data in the area. The case study is Mirak; a Paleolithic site located about 8km south of the modern city of Semnan. The site is comprised of 8 mounds, of which the mound no. 8 was selected for the excavation. The mound itself is of aeolian origin which has been formed throughout Holocene and is responsible for the covering of the Late Pleistocene deposits. Regarding the huge scatters of stone tools and the absence of cultural layers in the landscape, it is logical to assume that the aeolian mound has conserved archaeological deposits beneath. Contrary to the mound, Pleistocene cultural deposits were formed under alluvial regime in a floodplain during a period of relatively cold and humid. In addition, contemporaneous to the terminal Pleistocene, a hiatus of some millennia divided the alluvial sequence from the topmost Holocene sediments, ending the Paleolithic occupation of Mirak. At least, three Paleolithic cultural layers are identified in this site. The Methodology of this research is combining information from multidisciplinary analyses conducted in Mirak, and then, presenting some preliminary explanations in the framework of Human Behavioral Ecology (HBE). In doing so, in the framework of PhD dissertation of the corresponding author, data gained from lithic and faunal analysis, sedimentology, geomorphology, granulometry, micromorphology, mineralogy, and absolute chronology were combined. Moreover, the bibliographic resources regarding the climatic-environmental fluctuations in a regional scale (Iranian Plateau and the Asian Southwest) were added to the excavation data to check the probable correlations. The sedimentological evidence of Mirak indicates frequent water table and humidity fluctuations throughout the Pleistocene, which probably is comparable to the known millennial-scale climatic fluctuations during the LGC (Dansgaard-Oeschger or D-O events). The subsequent changes in floral/faunal composition in response to such fluctuations in the region are presumable. The evidence of teleconnection between Late Pleistocene Greenland (D-O events) and continental Asia has been indicated based on the Chinese Loess Plateau, the eastern part of Central Asia, Northern Iranian Loess, and the western part of Dasht-i Kavir. Such teleconnection may further affirm the claimed relationship between continental-scale climatic fluctuation and local evolution of climate-environment throughout the NICD. The LGC is generally considered a cold and dry period on continental scale. As a result, the fragmentation of landscapes is expected in continental regions such as the NICD. Therefore, using the data recovered from the fieldworks conducted in the region plus bibliographic investigation on the climatic records on regional and continental scales, one could preliminarily deduce the paleoenvironmental characteristics of the NICD, the timeframe during which human occupied the region, and some other mobility- and subsistence-related features. Based on characteristics such as the presence of Levallois-Mousterian flake-based assemblage in company with prismatic laminar products, the archaeological deposits of Mirak could be placed in the second half of the late Pleistocene, MIS 3 in particular. Thus, from the archaeological point of view, Mirak belongs to the Late Middle and Upper Paleolithic periods. The results of OSL and post-IR IRSL datings confirm this claim, as well. In combining lithic and environmental data in the framework of Ecology, it is suggested that logistical mobility in Mirak was high and the site was probably a central place in its own right. Moreover, the presence of human groups was frequent but discontinuous. Based on similarities between Mirak and the three other mentioned archaeological sites, such results could likely be claimed for them, as well. Presumably, none of the archeological sites represents continuous presence of hunter-gatherers during the Late Pleistocene. Finally, it seems the NICD roleplayed both as a corridor for the expansion of human range and a magnet for living throughout the later part of Late Pleistocene.