| The northeast Qinghai-Tibet Plateau is one of the major areas of human activity since late Pleistocene, extreme and fragile environment is complex and have close relationship with human activity. So to research the relationship between human activities and environmental evolution in this area has the particularity and typicality. In past research suggests that the Qinghai-Tibet Plateau between 40-30 ka had a special warm wet period. And the Tibetan plateau is the earliest prehistoric human activities is also believed to appear roughly between 40-30 ka, at the environment background of so-called "Tibetan plateau three stage special warm wet period". However, in recent years the reconstruction of the lake lever change and climate records study in Qinghai-Tibet Plateau shows that the abnormal warm, moist MIS3 does not exist. This understanding differences because of C14 dating method relatively limited range of about 30 ka to dating. Therefore, independent framework and system of the prehistoric human activity of the Qinghai-Tibet plateau has to obtain Based on the s under the framework of prehistoric evolution of the relationship between human activities and climate environment should be combed anew.In our research, through a comprehensive consideration of the differences between different regions of the Qinghai-Tibet Plateau environment conditions, the importance of location and the integrity of the archaeological strata, Choose the Qinghai lake basin, Qaidam basin and the Yellow River upstream of the prehistoric human activity sites as the research site,At the same time, consider the methods for dating range, we take use of Single Aliquot Regeneration of OSL combined with radiocarbon dating methods, Access to the Qinghai-Tibet plateau prehistoric human activity time series, And select the corresponding with the archaeological site for environmental indicators of stratigraphic profile analysis, to investigate the relationship between the prehistoric human activities and climate environment.Through the ruins of prehistoric human activities,using OSL dating method to date the samples of archaeological strata of the system, At the same time, according to theresults of carbon dating to verify the dating results of OSL. For continuous stratigraphicprofile use pollen, particle size, organic matter, magnetic susceptibility, chromaticity andenvironment index analysis to established in the framework of series of prehistoricclimate background of human activity and the coupling relationship. In this paper, weobtain the following conclusions:(1) The earliest prehistoric human activity in Qinghai lake area began at about 14 ka BP. During 9~6 ka period, Temperature and precipitation combination to match the best, Suitable climate offers more resources for mankind, and the rise of fine stone leaf process make human food ability increase, adapt to the scope of further expansion to the edge of the environment. in the best climate in 9~6 ka, Qinghai lake region microlithic cultural boom. After 6 ka BP, the monsoon fade out, the climate frequently fluctuated, transition depends on the climate environment of microlithic culture gradually decline, Neolithic culture began to emerge, The discovery of the earliest pottery and ground rods in Jiangxigou2 site shows that Plateau m icrolithic cultural factors may be in part integrated into agriculture in 6 ka BP, And began to enter the Neolithic age.(2) The age of Xiao Qaidam archaeological layer is through reconstruct two paleolake terraces to get the age of prehistoric human activity in this area. the age of first terrace in Xiao Qaidam lake is between 12.6±1.1 ka and 3.1±0.3 ka,about 4 miters above the lake. The age of second terrace is between 37±4 ka and 51±4 ka, about 40 miters above the lake, the archaeological layer of Xiao Qaidam is about 7 miters above the lake. So we believe that the age of prehistoric human activity in Xiao Qaidam is between12.6ka and 37 ka.(3) Through system dating the dammed lake of Ji Shi gorge in the upstream ofLajia site, two lake sedimentary Ji Shi gorge were identified: one is around roughly 30 ka,Another began roughly at 8.9 ka. And the age of lake dam yonger than 6.8 ka. Althoughthe radiocarbon dating results of choral On the border of colluvial deposit and lacustrinestrata is 4ka BP, the result maybe has some relationship in time with The earthquake inLajia caused landslide, but due to lack of enough geomorphic evidence, we can not givethe result that the destroyed of Lajia site was caused by the lake dam of dammed lake.ofJi Shi gorge.(4) The OSL dating method is a good applicability in Qinghai-Tibet plateau to get the age of Prehistoric human activity, OSL dating results from the corresponding site layer almost the same as the radiocarbon dating from the layer of site,to achieve the purpose of the cross test. |
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