| The loess deposit on the Chinese Loess Plateau are valuable records of past climate and environmental change.Meanwhile,numerous ancient human and Paleolithic remains are founded in the loess deposits.In recent decades,scholars have investigated large number of ancient humans,Paleolithic and Neolithic sites on the southeastern margin of the Loess Plateau and Qinling Mountains.However,due to the lack of dating materials,Paleolithic site with absolute dating is still rare in this region.The ages of some sites are roughly estimated by stratigraphic comparison or deducted based on stone features or animal fossil in comparison to other sites with age controls.As a result,without precise age controls on these sites,it is hard to further discuss the timing of ancient human life and stone technology evolution,the coupling relationship between prehistoric human activities and natural environment evolution,and the impact of ancient human activities on the regional geomorphological evolution.OSL(Optically Stimulated Luminescence)dating technique has been greatly developed in recent years.And the Single-aliquot Regenerative dose protocol(SAR)has a unique advantage in loess OSL dating,since the accuracy and precision of OSL ages are significantly improved.However,due to the premature saturation of the quartz SAR signal,the dating range of the quartz OSL dating is limited.With the development of new protocols such as quartz TT-OSL(Thermally transferred optically stimulatedluminescence,TT-OSL)and feldspar pIRIR(post-IR infrared(IR)stimulated luminescence,pIRIR),the upper limit of the luminescence dating can reach up to-200-300ka,which provides the possibility to date the loess Paleolithic sites accurate and precisely.In this paper,sampling and equivalent dose tests were carried out on a Paleolithic site in Liangshan Village,Shaanxi Province,which on the Southern Qinling Mountains,and a Neolithic site in Yangshao Village,Henan Province,which on the southeastern margin of the Loess Plateau.Based on these dating results,we found some conclusions:(1)Although the loess accumulated in the intermontane basin of the southern Qinling Mountains is different from the typical loess in northern China,the OSL method can also be applied to these atypical eolian loess.When dating the Paleolithic sites in the Loess Plateau,we should combine quartz TT-OSL and feldspar pIRIR methods to obtain a more accurate age.(2)The Liangshan Village site in Hanzhong,Shaanxi Province is one of the earliest middle Paleolithic sites in the Hanzhong Basin of the Qinling Mountains.Its discovery proves that ancient humans once li,ved in the Han River basin in the south of the Qinling Mountains200,000years ago(S2period).(3)The formation time of the gully terraces in the Yangshao site is about 30ka to 120 ka,corresponding to the marine isotope stage(MIS)3 and stages 5,respectively.According to the paleoclimatic record reconstructed from Luochuan loess-paleosol using magnetic susceptibility index,the East Asian summer monsoon is strong and the precipitation increased significantly during the period.Therefore,the abundant precipitation may be the main cause for the rapid cutting of the gully in the Yangshao site.The influence of ancient human activities is limited.(4)The atypical loess overlying the gully terraces in the Yangshao site has complex origin,and its OSL signal is also confusing,so it is difficult to apply OSL dating here.Frequent surface activities and fire behaviors of ancient humans may influence loess'OSL signals that layer and some layers around. |
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