太湖地区多剖面地层学分析与良渚期环境事件

Analysis of stratigraphy on multi-profiles in the Taihu Lake region and paleoenvironmental events in the Liangzhu culture epoch

太湖地区多剖面地层学分析和环境考古研究表明:本区良渚期为全新世大暖期中气候逐渐向干凉转变的时期,但大部分时间里仍略比今天暖湿。良渚期末气候走入低谷并剧烈波动,良渚期侵蚀面反映一次较长时间的海面下降过程,气候剧烈波动的转型期与海面下降至低海面过程相一致。此时本区洪积层、埋藏遗址及遗址地层中文化间歇层等发育皆反映古洪水泛滥事件的存在;而良渚期侵蚀面上的铁锰结核聚集现象及现没于水下的众多良渚期开挖的古井等遗迹还反映出这一时期也曾发生过气候干燥事件。分析认为良渚文化繁荣发展期陆地面积扩大,气候略好于今天;而良渚文化衰亡期则处于4300～3800aB.P.间的水、旱灾丛生的低海面气候异常期。

The Shahe profile in Dongling, Liyang, the Caoxieshan site in Weiting, Suzhou and Maqiao site in Maqiao town, Shanghai are chosen as the major research objects on stratigraphy, from which we analyze and study the paleo-corroding surface, deposit char- acteristics, sporo pollens, chemical elements, 14C dating and climate transformation curve transformed by chemical composition from the stratum of the Maqiao site in Shanghai, combined with the analysis of the regional paleoenvironment and environmental archaeolo- gy as well as the research results of the temporal and spatial distribution of archaeological sites since the Neolithic Age in the Taihu Lake region. The research results indicate that the climate of Liangzhu epoch in the Taihu Lake region increasingly changed towards col- der and drier than that of its former time in Holocene Megathermal period, however, much more time of it was still warmer and wetter than today. In the end of Liangzhu ep- och, the climate was at the lowest position and showed rapid and violent fluctuation, which matched well a long time course of seaqevel falling that was reflected by the paleo- corroding surface of Liangzhu epoch. The flood accumulation layers, the buried ancient trees, the buried archaeological sites and cultural interruption, etc. prove the existence of the ancient floods; the iron manganese concretion and the ancient wells under water such as the Taihu Lake, Chenghu Lake and the Taishidian in Zhouzhuang etc. today reflect on the dry periods or drought events. The background of Liangzhu cultural development was that the sea-level in the Taihu Lake region was slowly failing, the area of fresh-water lakes and marshes were increasingly decreasing, which made the land increasingly exposed; in the meantime, the climate was slightly better than that of today. In 4300-3800aB. P. , the low sea-level, the abnormal climate as well as the frequently occurred floods and droughts were the environmental background of Liangzhu culture towards the decline and fall. We think that the direct reason for the decline and fall of Liangzhu culture is more complicated than we have imagined ever, however, the frequently occurring floods and droughts as well as the abnormal climate should be seriously fatal hit for Liangzhu people living on the paddy growing, fishing and hunting.