闽江下游黄岐屿遗址的光释光测年

Optically Stimulated Luminescence Chronology of the Huangqiyu Site of the Lower Min River

为了更好地理解闽江下游的连江县黄岐屿遗址的环境背景和考古年代,在已有AMS14C年代学研究的基础上,选择黄岐屿遗址的T2剖面进行年代学样品采样,在室内运用中颗粒石英的单片再生剂量法进行光释光年代学研究。结果表明:黄岐屿遗址地层的OSL埋藏年龄范围为8.5±0.5-4.4±0.2 ka,属于早-中全新世阶段的沉积/文化地层。其中2019118样品的年龄为4.4±0.2 ka,属于昙石山文化,与AMS14C年龄相当;2019117样品年龄为5.7±0.3 ka,可能存在年龄的高估;2019119样品的年龄为8.5±0.5 ka,受采样环境的影响,该地层的OSL埋藏年龄可能指示遗址底界的最大年龄。对比黄岐屿遗址所在的福州盆地地貌和环境演化过程以及区域史前人类活动发现,该遗址对应6 500-4 000 a B P的大暖期气候和相对高海面时期,该时期福州盆地发育了众多的同时期的史前遗存,区域内产生了繁荣的昙石山文化和昙石山下层文化。新石器时代末期4.2-4.0 ka气候突变的冷事件、4 000-3 000 a B P太平洋两岸热带-亚热带地区的气候环境的急剧变化以及北方吴越文化的侵入可能是造成该遗址缺失后续文化遗存的原因。

Prehistoric human cultural sites along the eastern coast of Fujian Province are important records for studying the origin and spread of the Austronesian civilization. The Huangqiyu site is the first Tanshishan culture site to be unearthed in the Min River estuary area and was excavated by scientific archeology. It has great significance for further research of the Tanshishan culture and the coupled relationship between prehistoric human activities and environmental changes in the Fujian coastal region. The chronology of archeological sites is an important foundation for prehistoric archeology. In this study, the burial age of the Huangqiyu site in Lianjiang County was analyzed using the Optically Stimulated Luminescence(OSL) dating technique on the basis of Accelerator Mass Spectrometry(AMS)14 C dating. In the field, the T2 section of the Huangqiyu site was selected for sampling, and the single-aliquot regeneration dose method of medium-grained quartz was used to assess OSL chronology in the laboratory. The results showed that the OSL burial age of the Huangqiyu site ranges from approximately 8.5 ± 0.5 to 4.4 ± 0.2 ka, corresponding to the sedimentary/cultural strata of the early Middle Holocene. The OSL age of sample 2019118, which was consistent with the AMS14 C age, was 4.4 ± 0.2 ka,corresponding roughly to the Tanshishan culture. The age of sample 2019117 was 5.4 ± 0.3 ka, which may be an overestimation because the equivalent dose of this sample showed a weakly skewed distribution with a tail at the high value end, indicating that there was a small amount of sundry particles and that the drying was insufficient.This problem may have led to a bias in the measured equivalent dose and, in turn, to overestimation of the age of the sample. The age of sample 2019119, which was affected by the sampling environment, was 8.5 ± 0.5 ka,possibly indicating the maximum age of the bottom boundary of the site. Archeological studies have found that the age indicated by the pottery features excavated from the cultural layer at the bottom of the Huangqiyu site is most likely earlier than the Tanshishan culture, or possibly that of the lower strata of the Tanshishan culture.Overall, the ages of samples 2019117 and 2019119 are different from the AMS14 C ages, but these are consistent with the archeological characteristics of the site. By comparing the geomorphological and environmental evolution process of the Fuzhou Basin, where the Huangqiyu site is located, with the regional prehistoric human activities, it was found that the site corresponds to the warm climate of 6 500-4 000 a B P and relatively a high sea level period. Many prehistoric remains were developed in the Fuzhou Basin during this period, and the prosperous Tanshishan culture and the lower Tanshishan culture emerged in the region. At the end of the Neolithic age, the abrupt cold event of 4.2-4.0 ka, the drastic change of climate and environment in the tropical and subtropical regions on both sides of the Pacific Ocean at 4 000-3 000 a B P, and the invasion of the northern WuYue culture may explain the disappearance of the follow-up culture. Because of the limited precision of the regional sea-level change curve, it is insufficient to discuss sea-land change and the coupled relationship with human activities. Relevant studies need to strengthen these aspects in the future.