长江中游荆州―公安段洪水滞流沉积物特征分析  

FEATURE OF THE GREAT FLOOD SLACKWATER DEPOSITS IN THE JINGZHOU-GONG’AN SECTION OF MIDDLE REACHES OF THE YANGTZE RIVER

作　　者：周慧 吴立 朱诚[3] 李枫[2] 李林英[1] 路曙光 孙小玲 ZHOU Hui;WU Li;ZHU Cheng;LI Feng;LI Lin-ying;LU Shu-guang;SUN Xiao-ling(Provincial Key Laboratory of Earth Surface Processes and Regional Response in the Yangtze-Huaihe River Basin,School of Geography and Tourism,Anhui Normal University,Wuhu 241002;State Key Lahoratory of Lake Science and Environment,Nanjing Institute of Geography&Limnology,CAS,Nanjing 210008;School of Geography and Ocean Science,Nanjing University,Nanjing 210023)

机构地区：[1]安徽师范大学地理与旅游学院,江淮流域地表过程与区域响应安徽省重点实验室,安徽芜湖241002 [2]中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,江苏南京210008 [3]南京大学地理与海洋科学学院,江苏南京210023

出　　处：《地层学杂志》2020年第1期56-63,共8页Journal of Stratigraphy

基　　金：国家自然科学基金(41771221);中国博士后科学基金面上项目(2018M632403);黄土与第四纪地质国家重点实验室开放基金(SKLLQG1851);中国科学院数字地球重点实验室开放基金(2015LDE012)联合资助。

摘　　要：在野外考察的基础上,对长江中游荆州―公安段学堂洲、文村夹和二圣洲三处1998年洪水滞流沉积物地层剖面进行了样品采集和粒度、磁化率特征分析,结果表明:1)洪水滞流沉积物中黏土成分较少,含量波动于3.38%~15.66%之间,主要成分为粉砂和砂;文村夹中、下部砂的含量较高,分别为79.9%和80.32%,其他点组分都以粉砂为主;2)各采样点不同深度层位的粒度概率累积曲线主要呈现两段式,普遍缺乏推移质组分,学堂洲下部和二圣洲中部虽呈现三段式,但推移质的含量非常小;3)洪水滞流沉积物的粒度组成不仅受形成时的水动力条件影响,还受其所处地理位置的影响,主要体现为各采样点下部层位沉积物粒径普遍大于上层,文村夹点各层沉积物粒径大于其他两个采样点;4)三个采样点洪水滞流沉积物磁化率变化范围为67.41~299.59SI,学堂洲和文村夹两处的磁化率远高于二圣洲,各采样点地层剖面下部磁化率均高于上部,同一采样点沉积物磁化率与粒度具有一定的相关性,具体表现为粒径越大,磁化率越高。Slackwater deposits(SWD) of 1998 flood was investigated and sampled in the Xuetangzhou, Wencunjia and Ershengzhou, at the Jingzhou-Gong’an section in the middle reaches of Yangtze River. Grain-size distribution and magnetic susceptibility were comparatively analyzed for the samples collected in different deposited places. The results show that: 1) the main components of the flood slackwater deposits are sand and silt, and the clay content is less, between 3.38%~15.66%. The silt is the richest ingredient in all samples except the middle and bottom layer of the Wencunjia;2) the probability cumulative grain-size curve of different depth layers of each sample point mainly presents two segments, and the components are generally lack of the bed load. Although the bottom layer of the Xuetangzhou and the middle layer of the Ershengzhou present three segments, their bed load content is very small;3) the grain-size composition of the flood slackwater deposits is not only affected by the hydrodynamic conditions at the time of formation, but also affected by their geographic location, which is mainly reflected in that the grain-size of the sediments in the bottom layer of each sample is generally coarser than that in the upper layer, and the grain-size of the sediments in the sampling point of the Wencunjia is coarser than that of the other two sampling points;and 4) the magnetic susceptibility range of flood slackwater deposits of three sampling points is 67.41~299.59 SI and the magnetic susceptibility values of Xuetangzhou and Wencunjia are much higher than the Ershengzhou. The magnetic susceptibility values of bottom part of each sampling point were higher than the upper. There is a certain relevance between the magnetic susceptibility and the grain-size, embodied in that the coarser the grain-size, the higher the magnetic susceptibility. The results of this study could provide the reference to the Jingzhou-Gong’an section in the middle reaches of Yangtze River flood control and disaster mitigation and soil and water

关 键 词：洪水滞流沉积 粒度 磁化率 长江中游 

分 类 号：P534.63[天文地球—第四纪地质学]