洪山剖面是太原盆地东南边缘一湖积台地上的第四纪中晚期沉积剖面 ,该剖面中的湖相层典型特征是 :质地均一的灰绿、黄绿色粉砂粘土层与含碳酸钙结晶体的沉积层呈互层分布。利用地层连续追踪及铀系测年法分析 ,剖面中的湖相层是在 S5古土壤发育晚期至 S1 古土壤发育早期这一时间段内沉积而成的 ,剖面当时所处的位置正位于太原古湖盆的湖岸地带 ,沉积环境受着气候干湿变化的强烈影响。当气候湿润时 ,湖面升高 ,湖盆扩大 ,剖面点被湖水淹没 ,接受着湖相粉砂粘土层的沉积 ;干旱时 ,湖盆变化则相反 ,剖面点出露气下 ,并因地下水毛管作用的结果在沉积层表面产生碳酸钙结晶体。该剖面的研究结果同时还表明 :由第四纪气候的干湿变化对太原盆地这样大的湖盆 ,只能产生数米的湖面升降波动 ;与构造因素引起的湖盆变化相比 ,这种波动是小幅度的 The Hongshan section is the mid-late Quaternary sedimentary section on a lake platform in the southeastern margin of the Taiyuan basin. The lake facies in the section are characterized by a homogeneous gray-green, yellowish-green silt clay layer and a carbonate- Deposits are interbedded. Based on the continuous stratigraphic tracing and uranium dating, the lake facies in the profile was deposited during the period from the later development of the S5 paleosol to the early development of the Palaeozoic. The section was located in Taiyuan The ancient lakeshore lakeshore, sedimentary environment is strongly affected by changes in the climate of wet and dry. When the climate is humid, the surface of the lake rises and the lake basin expands. The section point is submerged by the lake and receives the deposition of the lacustrine silty clay layer. When the lake is dry, the lake basin changes in the opposite direction, As a result, calcium carbonate crystals are produced on the surface of the deposited layer. The results of the section also show that: from the Quaternary climate of the wet and dry changes on the Taiyuan Basin, such a large lake basin, can only produce a few meters of fluctuations in the lake; compared with structural changes caused by the lake, this Fluctuation is small