扬子浅滩MIS6阶段以来沉积地层及环境演变

发布时间：2018-04-23 06:53

  本文选题：扬子浅滩 + 沉积地层特征　； 参考：《南京大学学报(自然科学)》2017年05期

【摘要】：通过对扬子浅滩钻孔岩性、沉积结构和构造以及微体古生物组合的综合分析,划分出5个沉积单元,同时结合沉积物定年数据和邻区若干钻孔的地层对比研究,将MIS6阶段以来扬子浅滩的环境演化划分为5个阶段,先后发育河流(MIS6),浅海,近岸浅海,浅海(MIS5),河口湾(MIS3)和浅海(潮流沙席)(MIS1).研究认为MIS6阶段低海面泥沙堆积的河流高地是扬子浅滩形成的古地形基础;MIS3阶段形成的河口湾沉积为扬子浅滩提供了大量的物源,加速了扬子浅滩在地形上的崛起,10ka~6ka逐渐建立的辐聚辐散潮流场,以及强潮流的改造为扬子浅滩的形成提供了动力条件.潮流作用形成的砂质沉积概率累积曲线是以滚动总体为主的三段式,频率曲线呈双峰式,与潮流期的粗颗粒搬运堆积和歇流期的细颗粒悬浮物落淤有关.
[Abstract]:Through the comprehensive analysis of lithology, sedimentary structure and structure as well as micropaleontological assemblages of the Yangtze shoal boreholes, five sedimentary units are divided into five sedimentary units, and combined with sediment dating data and stratigraphic correlation of several boreholes in adjacent areas, The environmental evolution of Yangtze shoal since the MIS6 stage is divided into five stages, including river MIS6, shallow, inshore, shallow water, estuarine bay, and shallow sea. It is considered that the river highlands with low sea level and sediment accumulation in the MIS6 stage are the paleotopographic foundation of Yangtze shoal and the estuarine sediments formed in stage 3 provide a large amount of material source for Yangtze shoal. It accelerates the rise of Yangtze shoal topologically and gradually establishes the radiation-convergence divergence tidal current field for 10ka / 6ka, and the transformation of strong tidal current provides the dynamic conditions for the formation of Yangtze shoal. The probability accumulation curve of sandy sediment formed by tidal current is a three-segment type dominated by rolling population, and the frequency curve is bimodal, which is related to coarse particle transport and accumulation during tidal current period and fine particle suspended matter falling and silting in the period of stopping current.
【作者单位】： 南京大学地理与海洋科学学院;海岸与海岛开发教育部重点实验室;中国科学院南京地理与湖泊研究所;南京大学地球科学与工程学院;
【基金】：国家重大科学研究计划(2013CB956501) 江苏省重点基金-扬子大三角洲全新世沉积体系(BK20130056) 国家自然科学基金(40776032)
【分类号】：P736.2
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本文编号：1790906