本文選題：揚子淺灘 + 沉積地層特征�。� 參考：《南京大學學報(自然科學)》2017年05期

【摘要】：通過對揚子淺灘鉆孔巖性、沉積結構和構造以及微體古生物組合的綜合分析,劃分出5個沉積單元,同時結合沉積物定年數據和鄰區(qū)若干鉆孔的地層對比研究,將MIS6階段以來揚子淺灘的環(huán)境演化劃分為5個階段,先后發(fā)育河流(MIS6),淺海,近岸淺海,淺海(MIS5),河口灣(MIS3)和淺海(潮流沙席)(MIS1).研究認為MIS6階段低海面泥沙堆積的河流高地是揚子淺灘形成的古地形基礎;MIS3階段形成的河口灣沉積為揚子淺灘提供了大量的物源,加速了揚子淺灘在地形上的崛起,10ka~6ka逐漸建立的輻聚輻散潮流場,以及強潮流的改造為揚子淺灘的形成提供了動力條件.潮流作用形成的砂質沉積概率累積曲線是以滾動總體為主的三段式,頻率曲線呈雙峰式,與潮流期的粗顆粒搬運堆積和歇流期的細顆粒懸浮物落淤有關.
[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.
【作者單位】： 南京大學地理與海洋科學學院;海岸與海島開發(fā)教育部重點實驗室;中國科學院南京地理與湖泊研究所;南京大學地球科學與工程學院;
【基金】：國家重大科學研究計劃(2013CB956501) 江蘇省重點基金-揚子大三角洲全新世沉積體系(BK20130056) 國家自然科學基金(40776032)
【分類號】：P736.2
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本文編號：1790906