颍河上游的地貌变迁对新石器晚期聚落分布的影响

为探讨地貌变迁与史前聚落的分布关系,分析了禹州浅井剖面的Rb/Sr比值、磁化率和粒度等环境代用指标。结果表明颍河上游地区在仰韶文化时期(磁化率均值87.7×10?8 m3/kg,Rb/Sr均值0.83)为暖湿的风化环境,在龙山文化时期气候变干(瓦店剖面的磁化率72.5×10?8 m3/kg,Rb/Sr均值0.66)。禹州马沟洞石笋δ18O序列识别了本区在11.2、9.1、5.0 kaBP存在3次气候波动,借助地貌-气候驱动理论,认为颍河上游地区新石器聚落所在阶地形成于11.2~10.6 kaBP前后。龙山文化时期(约4.6~4.0 kaBP)的干旱气候导致禹州段颍河河床不断抬升进而形成高河面时期,使得颍河上中游两岸稻作农业得以快速发展。本区的聚落分布从仰韶文化时期的地貌封闭型转变为龙山期的开放型,并形成多处大型城邑聚落,然而4 kaBP的降温和洪水过程摧毁了颍河上游平原地区多数史前聚落,本区的城邦文化逐渐衰落。

Impact of fluvial landform changes on the Neolithic settlement distribution in the upper reaches of the Yinghe River

Fluvial landform change is one of principal elements that constrained the Neolithic settlement processes and direction.In the upper reaches of the Yinghe River,paleo-environmental proxies from layers of the Qianjing Profile,Rb/Sr ratios,magnetic susceptibility and grain size distribution patterns suggest that the weather was hot-wet then in the Yangshao period(circa 7.0~5.0 kaBP),but warm-dry in the Longshan period(circa 4.6~4.1 kaBP).Also,from the stalactite of the Madonggou Cave,δ^18O record evidenced 3 climatic fluctuations at 11.2,9.1 and 5.0 kaBP respectively.In association with landform-climatic driven theory,we suggest that the first terrace of the Yinghe River on which the Neolithic inhabitation sites was formed around 11.2~10.6 kaBP.In the Longhsan period,however,the dry climate decreased runoff of the Yinghe River and aggradation was in predominance,which lifted river water level higher.The moat remains at the Wadian site showed that people started building barrages to irrigate crops especially rice-farming in the Longshan period.Simultaneously,the locales of habitats became more open than they were in the Yangshao period.However,the 4 ka cooling event and continuous floods cut the study area’s cultural vein,and the major settlements retracted to the Dengfeng basin from the Yuzhou plain.Since then the cultural form of this area had turned back to the closed type and planned to move their living space from the upper reaches of the Yinghe River to the Luoyang basin.