摘要：
Background,aim,and scope Nihewan Basin in North China preserves one of the most detailed sets of Paleolithic evidence from the whole of Asia,making it as an ideal site for paleontological,sedimentological,magnetostratigraphical and paleoclimatic studies. Yujiagou site is located on the northern bank of Sanggan River in the eastern Nihewan Basin,and contains both Paleolithic to Neolithic stone tools. A large number of microlith products,animal fossils and several pieces of early pottery were also unearthed in this site in 1977. This site provides important materials for the study of microlith culture during upper Paleolithic period. Previous ages of this site were obtained using Thermoluminescence/Optically Stimulated Luminescence dating with age uncertainties up to 10％ (a thousand years). Relatively,we tried to use AMS-14C (Accelerator Mass Spectrometry) dating methods,the accuracy of which is within 0.2％ (several decades),to establish a chronological framework for the study of the connection between environmental change and human activities during Late Quaternary. Combing the evolutionary sequence of Paleolithic culture in the Nihewan Basin and the archaeological significance of early pottery,this study enhances our understanding of early hominin colonization in the late Paleolithic period and the potential influence of microlith and pottery on the transition from Paleolithic to the Neolithic age. Materials and methods We picked out fourteen dating samples from the Yujiagou section,which has a total thickness of～550 cm. Dating samples were given an acid-alkali-acid pretreatment to obtain the insoluble fraction. Prior to making the accelerator measurement,all materials were combusted to CO2 and converted to graphite using a Fe-catalyst reaction. The radiocarbon analyses were determined with the Xi'an-AMS Center. Results Fourteen AMS-14C data were converted to the calendar year using IntCal13 program. The correction ages increase from 27.80 ka to 5.80 ka BP. The top of Neolithic cultural layer is located at 30 cm,which is dated 2.43 ka BP by linear extrapolation for the age of 140 cm,110 cm and 80 cm of Yujiagou site. The boundary between Neolithic cultural layer and Paleolithic cultural layer is at 130 cm. Interpolated linearly in the 140—110 cm range,the age of the transition is ～9.35 ka BP. In addition,by use of linear interpolation at 325—275 cm,the age of the Dark brown pottery at the depth of 300 cm is ～13600 years. Discussion On the basis of the studies and comparison of many Paleolithic remains covering from the early to the later periods,we are able to obtain a preliminary archaeological sequence of Paleolithic culture. The small stone tool tradition runs through the whole Paleolithic period from beginning to end and the Paleolithic culture obviously reveals the characteristics of inheritance and development in its evolution. During the late Paleolithic period,the microlithic tool tradition appeared and began to develop along with the small stone tool tradition. Even during the early Neolithic period,microlithic technology still existed. Microlith is likely to be directly involved in and led to changes in the human society. Otherwise,the age of pottery fragment at the depth of 300 cm was estimated to be ～13600 years. This age is older than the other three pottery from Nanzhuangtou site (12632—12238 years),Zhuannian site (11208—10405 years) and Donghulin (12105—11370 years) in North China,which means that Yujiagou pottery is the earliest pottery in North China. Recent research found the early pottery with the age of 20000—19000 years from Xianrendong Cave in South China. These results suggest that pottery making technology has been widely spread around ten thousand years ago in China. The invention of pottery marked fundamental shifts in human subsistence practices and sociosymbolic behaviors. Therefore the emergence of pottery also drives the human society to enter the New Stone Age,to a certain extent. Conclusions The chronological framework of the Yujiagou site spanned from 16.19 ka to 2.43 ka BP using thirteen AMS-14C calibrated ages and the conversion from the paleolithic to the Neolithic age happened ～9.35 ka BP. Yujiagou pottery was made ～13600 years ago and the earliest pottery in North China. Under the background of climate warming of the last stage of the Late Pleistocene the pottery and microlith largely facilitated social change from the Paleolithic into Neolithic age in North China. Recommendations and perspectives This work accurately provide the chronology of Yujiagou site by using high-precision dating method. It is recommended that much more work should be carried out to deepen the cognition of the transition from the paleolithic to the Neolithic age.%于家沟遗址作为泥河湾盆地中唯一具有新旧石器工业过渡的典型遗址,为研究东亚旧石器向新石器时代过渡提供了理想的场所.本文通过于家沟遗址剖面沉积物(厚约550 cm)的加速器质谱法(AMS-14C)年代测定,确定了于家沟剖面的年代跨度为16.19—2.43 ka BP,其中旧石器向新石器时代的转化时限为9.35 ka BP.该遗址中发现的最早陶器经同层位地层推测,其年代为13.60 ka BP,是目前中国北方发现的最早陶器.陶器的使用可能改善了古人类的生活条件;大量细石器反映出泥河湾盆地中采猎经济高度繁荣.因此,在晚更新世末期气候开始变暖的背景下陶器和细石器的出现一定程度推动了中国北方旧石器时代向新石器时代的转变.
