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本文通过生物、粒度、重矿物、微量元素和~(14)C测年等分析,研究上更新统上段暗绿色硬土层的沉积特征和成因。根据孢粉组合和~(14)C测年资料确定该硬土层为玉木冰期末期产物。从硬土层的分布广、厚度小、底面倾斜等特点和生物、粒度、重矿物等特征分析,属河漫滩洼地沉积或河漫滩型湖沼沉积。上海东部地下30m以内有一层硬土层(Q_3~3);上海西部有两层硬土层,第一硬土层属全新统,第二硬土层属上更新统上段。
In this paper, the sedimentary characteristics and genesis of the dark green hard layer in the upper Pleistocene are studied by means of biological, granularity, heavy minerals, trace elements and ~ (14) C dating. Based on the sporopollen assemblages and ~ (14) C dating data, the hard soil layer was identified as the end of the Tamaki ice age. From the hard soil layer is widely distributed, the thickness is small, the bottom of the slope and other characteristics and biological, granularity, heavy minerals and other characteristics of the river flood plain depression or floodplain type lake lakes deposition. There is a layer of hard soil within 30m below the ground in eastern Shanghai (Q_3 ~ 3). There are two layers of hard soil in the west of Shanghai, the first hard layer belongs to Holocene, and the second hard layer belongs to Upper Pleistocene.