河北康保兴隆遗址的光释光测年研究

兴隆遗址是长城以北裕民文化分期研究的重要遗址。作为坝上高原迄今为止发现的出土遗物最丰富、沿用时间长达数千年的遗址, 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, 而且对研究中国北方旧-新石器时代过渡、农业起源及其环境背景等问题具有重要意义。兴隆遗址发掘后, 虽然其新石器文化层已通过¹⁴C方法进行了测年, 但其旧-新石器时代过渡期的文化层尚未进行年代学方面的研究。本研究在地层结构划分基础上, 对兴隆遗址的TG01探沟的G5剖面(42°N, 115°E; 海拔高度为1398m; 剖面研究深度为106~361cm)进行采样, 共采集有11个沉积物样品, 提取出粗颗粒(90~125μm)和细颗粒(4~11μm)两个粒级的石英, 利用光释光(OSL)测年技术中的单片再生剂量法(SAR), 对兴隆遗址探沟的不同文化层位进行年代测定, 建立了兴隆遗址的整体年代框架。通过对两种粒级的石英的释光年代比较, 得出细颗粒石英的所测年龄高于粗颗粒石英, 高出年龄约为600~2000年左右, 这可能是沉积过程的不完全晒退导致的。且基于粗颗粒石英的光释光年龄与¹⁴C年龄之间良好的一致性, 认为粗颗粒石英的光释光年龄更加可信; 并首次确定了兴隆遗址旧-新石器时代过渡期文化层的光释光年龄为距今13.4±1.8~10.7±0.9ka(以粗颗粒石英样品的年代为准)。

Optically stimulated luminescence dating of the Xinglong site in Kangbao,Hebei Province

The Xinglong site is significant for the staging study of the Yumin culture in the north of the Great Wall, which is located in the southeast of Xinglong Village, Zhaoyanghe Town, Kangbao County, Zhangjiakou City, Hebei Province. In the Xinglong site of the Bashang Plateau, ancient humans have been lived for thousands of years and left the most abundant relics. The determination of its age will not only help to clarify the time when the ancient humans appeared in this area, but also benefit for studying the issues such as the transition from the Paleolithic to the Neolithic, the agricultural origin and its environmental background in North China. Although the age of the Neolithic culture layer has been determined by the 14C dating method since the excavation of the Xinglong site, the chronology framework of the cultural layer in the Paleolithic-Neolithic transition period has not been studied. In this study, a pedo-stratigraphic sequence was established in the TG01-G5 moat gully section(42°N, 115°E; elevation for 1398 m; at 106~361 cm depth below the present ground surface)of the Xinglong site and a total of eleven deposits(L1~L11)were collected for optically stimulated luminescence dating. The coarse-grained(90~125 μm)and fine-grained(4~11 μm)quartz particles were extracted and the single-aliquot regenerative-dose(SAR)protocol was applied to date the different cultural levels and determine the overall chronology framework of the TG01-G5 in the Xinglong site. Conventional tests of the SAR protocol and the luminescence characteristics indicate that the OSL signal of quartz samples is dominated by the fast component and this protocol is suitable for dating the Xinglong site. In these eleven samples, fine-grained quartz OSL ages(3.0±0.1~15.6±0.7 ka)were overestimated by ca. 0.6~2.0 ka compared with ages of coarser fractions(2.5±0.2~13.4±1.8 ka), possibly due to incomplete bleaching at deposition. We believe that the coarse-grained quartz OSL ages are more reliable, which show good agreement with the 14C ages. For the first time, the OSL age of the Paleolithic-Neolithic transition period in the Xinglong site was determined as 13.4±1.8~10.7±0.9 ka based on the coarse-grained quartz samples.