怀来盆地珠窝堡遗址ESR年代学初步研究

ELECTRON SPIN RESONANCE DATA OF THE ZHUWOBAO PALEOLITHIC SITE IN THE HUAILAI BASIN OF CHINA

作为“大泥河湾”考古的重要组成部分,怀来盆地是研究和探讨中国北方乃至东北亚地区更新世期间古人类生存行为、人群迁徙扩散以及文化交流等科学问题的重要地区.珠窝堡遗址的发现,不仅为怀来盆地的史前史研究提供了重要依据,更为泥河湾考古工作增添了新的亮点和坐标.珠窝堡遗址试掘后尚未进行年代学方面的研究,作为怀来盆地最新发现和首次试掘的旧石器遗址,其年代的确定不但有助于厘清古人类在这一地区出现的时代,而且对于建立该地区古人类行为适应、技术发展以及古环境演化的整体年代框架具有重要意义.本研究利用石英Ti-Li心ESR法对珠窝堡遗址样品进行了年龄测定,珠窝堡遗址的ESR年龄为504±76 ka,是怀来盆地内目前发现的年代最早的文化遗存.

The Huailai Basin is an important archaeological study area of the ＂Big Nihewan＂ （generalized Nihewan） Basin.It is an important area to research and explore the survival of the ancient human race,the migration and immigration of the population and the cultural exchange during the Pleistocene in North China,as well as in Northeast Asia.The discovery of the Zhuwobao site provides a significant basis for the prehistoric history of the Huailai Basin and adds new highlights to the Nihewan archaeological work.There is no geochronology data in this area until now.As the latest discovery and first excavation Paleolithic sites in Huailai Basin,the geochronological identification of Zhuwobao site will help to know the age of the ancient human beings in this region.It is of great significance to establish the overall geochronology framework of ancient human behavior adaptation,technological development and paleoenvironment evolution in the region.The Zhuwobao site（40°15′50″N,115°34′12″E） was excavated in 2014 in Huailai Basin.The location of the site is about 1.5 km away from the town of Zhuwobao Village,Huailai County,Hebei Province.It is deposited on the third terrace of the Yongding River.The depth of the profile excavated at the site of Zhuwobao exceeds 12 m,and the cultural layer was located at the underneath of the profile with a thickness of about 2.7 m.In order to determine the absolute age of the culture layer,3 samples（HL-02,HL-03 and HL-04）were collected at different depths of culture layer,and the distance from the top of profile were 8.0 m,8.6 m and 9.2 m,respectively.At the same time,in order to limit the age of the site,we collected ESR sample HL-01 in the stratum above the cultural layer and ESR sample HL-05 in the stratum under the culture layer,the distance from the top of profile were 4.3 m and 10.3 m,respectively.In order to investigate the sunlight bleaching characteristic of Ti-Li center and Al center,we selected the HL-02 sample to design the sunlight bleaching experiment,and the artificial sunlight time was 0～ 1078 h.The equivalent doses of Al and Ti-Li centers were obtained by exponential fitting,and then we discussed the bleaching kinetics of Ti-Li and Al centers of quartz before the last deposition and burial.The Ti-Li and Al center ESR signal intensities decrease rapidly with the accumulation of sunlight bleaching time.The Ti-Li center has completely reset to zero after 50 h while the Al center achieve a stable residual after 400 h.The equivalent dose of the Ti-Li and Al centers of HL-02 was 1932±179 Gy and 1942±288 Gy,respectively.The sunlight bleaching experiment results show that the sample HL-02 had received adequately sunlight bleaching before the last deposition and burial,so the Ti-Li center ESR age is reliable.Then we fitted out the equivalent dose of the other samples and calculated the ages of the samples according to the ESR dating principle.Our results indicate that the ESR age of Ti-Li center at the Zhuwobao site was 504±76 ka.The results suggest that the Zhuwobao site is the earliest cultural site of the Huailai Basin.The ESR geochronology study of the Zhuwobao site is of great significance to establish the overall geochronology framework of ancient human behavior adaptation,technological development and paleoenvironment evolution in the region.In addition,this study provides an effective for the determination of the independent age of the Middle Pleistocene site in Huailai Basin.