【摘要】 为探究史前先民遗址沉积物粒度特征对古人生存环境的意义,采用激光粒度分析方法对长山遗址三个剖面的174个剖面样品进行了粒度分析.结果表明:含文化层剖面和自然剖面的沉积物均以砂为主,分选较差,偏度为正偏,峰度多为尖窄峰.运用标准偏差法将自然剖面沉积物分为组分1(2～15μm)、组分2(15～150μm)、组分3(150～700μm),组分3与东辽河中游河漫滩剖面粗粒组分粒径大小一致,说明组分3主要来源于东辽河,其含量可间接指示近7 800a以来夏季风的强弱,具体可分为4个阶段:7 800～5 000a(BP)期间,东亚夏季风强度较强;5 000～2 100a(BP)期间,夏季风强度整体较弱,但在3 800～3 100a(BP)期间强度增大;2 100～900a(BP)期间,夏季风强度增强;900～500a(BP)期间,夏季风减弱.长山遗址文化层存在于3 500～3 200a(BP)期间,揭示长山史前先民在夏季风强度较强时期创造了东辽河文明.更多还原

【Abstract】 The study of sediment grain-size in the prehistoric ancestral sites is of great significance to explore the ancient peoples living environment.In this paper,a total of 174 samples were tested by Microtrac S3500 laser particle size analyzer.These samples were from three profiles:the prehistoric ancestors cultural profile in Changshan site,the natural profile which were not affected by the human activities,and the profile in floodplain of East Liaohe Rivers middle reaches.Then combining with the AMS14 C ages the material sources and grain-size characteristics of the profile containing cultural layer and natural profile were analyzed.Next the ‘Grain-size class vs.standard deviationmethod were applied to extract the sensitive grain-size component in the sediment to further reveal the paleoenvironment significance.The results show that both the natural profile and the profile with culture layer are mainly composed of sand.The profiles have bad sorting,positive skewness,and pointed narrow kurtosis.The natural profile sediments can be divided into component 1(2～15μm)component 2(15～150μm)and component 3(150～700μm)by standard deviation.Comparing component 3 with coarse-grained component in the floodplain profile of the middle reaches of the East Liaohe River it can be seen that the grain-size of the two components are same,and component 3 was mainly from the East Liaohe River.So the percentage of component 3 can be used to infer ancient precipitation and indirectly indicate the strength of the summer monsoon.The variations of East Asian Summer Monsoon since nearly 7 800 a(BP)can be divided into the following four periods:during7 800～5 000 a(BP)period the East Asian Summer Monsoon were strong;from 5 000 to 2 100 a(BP),the overall intensity of East Asian Summer Monsoon is weak,but it increased during the period of3 800～3 100 a(BP);during 2 100～900 a(BP)period the summer monsoon strength increased again;and the summer monsoon strength decreased from 900 a(BP)to 500 a(BP).The Changshan site cultural layer existed during the 3 500～3 200 a(BP)period when the intensity of summer monsoon was strong,which revealed that the prehistoric ancestors in Changshan site created the East Liaohe River civilization in the period of strong East Asian Summer Monsoon.更多还原