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通过玉溪遗址T0403探方11个古洪积层粒度参数分析,发现该遗址古洪积层的特征是:①遗址古洪积层粒度频率曲线为单峰正偏,分选差,概率累积曲线为典型三段式,且推移质组分>40%;②洪积层角闪石、磷灰石等不稳定矿物含量高于现代洪水层,表明古洪积层主要为近源沉积。联系到古洪积层形成期(6.3~7.5 ka B.P.)属于全新世大暖期的高温波动期,干湿波动是造成玉溪地区洪水频发的主要原因,同时根据遗址文化地层出土的器物判断,古洪积层沉积粒度特征变化与新石器人类的农业生产活动有关。
Through the analysis of eleven ancient flood accumulated particle size parameters of T0403 exploration site in Yuxi site, the characteristics of ancient flood accumulation in this site are: ① The ancient flood accumulation granularity frequency curve of the site is single peak forward deviation with poor sorting, the probability cumulative curve is Typical three-stage type, and the plutonic component> 40%; (2) The content of unstable minerals such as hornblende, apatite in the alluvial layer is higher than that in the modern flood layer, indicating that the paleo-buildup is mainly near-sourced sediments. It is concluded that the paleo-buildup formation (6.3-7.5 ka BP) belongs to the period of high temperature fluctuation during the Holocene Megathermal. Fluctuations in wet and dry conditions are the main causes of frequent floods in Yuxi area. According to the utensils unearthed from the cultural strata of the site, Changes in grain-size characteristics of paleo-buildup sediments are related to agricultural production activities of Neolithic humans.