南通地区冰后期泥沙沉积量和环境变化的初步研究

南通地区位于长江三角洲北翼，其冰后期的环境变化以最大海侵时期为界，之前为海侵期，表现为海水入侵，陆地面积减少。之后海面趋于稳定，长江泥沙在河口地区持续沉积的作用下，表现为南通地区的逐渐成陆过程。利用收集的84个分布于南通地区及附近的钻孔剖面资料，将其按不同厚度的沉积相进行整理，结合前人研究成果，根据不同的数据基础运用IDW（Inverse Distance Weighted）插值对南通地区冰后期沉积厚度分布和环境变化过程分别进行了初步研究。结果表明：南通地区古河谷区是冰后期主要的泥沙沉积区，沉积物厚度、体积和重量大于北翼地区，北翼前缘沉积要大于后缘。冰后期古河谷区沉积泥沙4 8922×108 t，北翼地区沉积泥沙1 0453×108 t，二者之比约为47〖DK〗∶10，泥沙沉积强度之比约2〖DK〗∶1。从冰后期海侵初期到最大海侵时期，再到南通成陆的晚期，南通地区水域面积比例先由622%上升到95%，再缩减到331%，陆地面积比例先由378%缩减到5%，而后又上升至669%。尽管钻孔资料可以为南通地区有历史记载之前的时期提供宏观的环境变化框架，但由于钻孔资料在测年数据及沉积相的划分方面分辨率较低，在表现南通地区历史时期的环境变化方面存在不足，需要结合考古、文物等历史资料和土壤分布等自然地理信息进行更为详细的研究

PRELIMINARY STUDY ON SEDIMENT FLUX AND ENVIRONMENTAL CHANGES IN NANTONG AREA SINCE POST-GLACIAL

Nantong area located in the north wing of Changjiang delta.According to the transgression maximum in post-glacial,changes of environment in Nantong area was divided into two stages:transgression and regression stage.During transgression,water area increased and land area decreased in Nantong area.Contrary to transgression stage,formation of Nantong area was mainly in regression stages.Collected 84 boreholes nearby or in Nantong area were used to identify environment changes in the post-glacial based on different sedimentary facies with different depth.IDW(Inverse Distance Weighted) method was used to study the process of environment change of Nantong area.Results show that sediment thickness,volume and weight of paleovalley were larger than the northern flanks,and the front of northern flank was larger than the back.Sediment deposition in paleovalley was 4 892.2×108 t and 1 045.3×108 t in northern flanks since post-glacial.Ration between paleovalley and northern flank nearly 4.7∶1,and the intensity of deposition ration nearly 2∶1.Rose of water area in Nantong from 62.2% to 95% from the early transgression to transgression maximum,and then decreased to 33.1% in the late regression.On the contrary,land area was reduce from 37.8% to 5% and then rose to 66.9%.The framework of environmental changes was provided by the boreholes data before literature recorded.New boreholes,historical data,soil distribution and other natural geographical information were needed for detailed research.