巫山地区三类黄土沉积物的粒度特征及物源启示  

Grain size characteristics and source enlightenment of the Wushan loess in the Yangtze Three Gorges area

作　　者：朱晓雨 刘连文[1] 孟先强 ZHU Xiaoyu;LIU Lianwen;MENG Xianqiang(Ministry of Education Key Laboratory of Surficial Geochemistry,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]表生地球化学教育部重点实验室,南京大学地球科学与工程学院,南京210023 [2]湖泊与环境国家重点实验室,中国科学院南京地理与湖泊研究所,南京210008

出　　处：《地球环境学报》2019年第6期579-589,共11页Journal of Earth Environment

基　　金：国家自然科学基金项目(41991321,41690111)。

摘　　要：长江三峡地区的巫山黄土位于润湿地区,其来源及成因具有重要的古气候意义。黄土的粒度常用于指示其成因及源区,目前关于巫山黄土成因和来源还是存在许多争议,并且过去对巫山黄土粒度的研究主要集中于单一剖面,缺乏空间上的系统对比研究。基于此,对长江三峡巫山地区三个海拔梯度变化明显的黄土剖面进行系统的粒度组成分析,结果表明:顶部望天坪、中部圣泉和底部江东嘴剖面的粒度频率曲线大多表现为不对称的多峰特征。圣泉剖面以粉砂级粒径含量为主的特点说明它的风成成因,物源主要来自近缘河谷;江东嘴剖面呈现出两种完全不一样的峰型,可能由两种不同成因混合而成;位于望天坪剖面沉积物粒径要细得多,推测为远源风成物质。Background,aim,and scope The Wushan loess in the Three Gorges region of the Yangtze River is located in the wet area,and its source and genesis have important paleoclimatic significance.Previous studies have been conducted on the formation,provenance and times of Wushan loess,but the origin and provenance of Wushan loess are still controversial.Different scholars choose different locations in different regions to study Xiashu loess,which may be the main reason for the debate on its origin.The grain size composition of the sediment directly reflects the dynamic condition,sedimentary environment and transportation direction of the transport medium,which is often used as a discriminant index for the origin and origin of loess.However,in the past,studies on loess particle size of Wushan mainly focused on a single section,lacking systematic comparative studies in space,and lacking comparative studies on different sedimentary types.Based on this,this paper systematically analyzed the grain size of three loess profiles with obvious changes in elevation gradient in Wushan area of the Three Gorges of Yangtze river in China,and discussed the origin and material source of Wushan loess.Materials and methods This paper collected three loess profiles of different heights on both sides of the Yangtze river in Wushan area,they are the Jiangdongzui profile at the bottom of the east bank of the Yangtze river at an elevation of about 190.4 m,the middle Shengquan profile near Chengnanjiu wharf in Wushan county at an elevation of about 248.6 m,and the top Wangtianping peak profile at the south bank of the Yangtze river in Wushan county at an elevation of about 1413.5 m,opposite the entrance of Daning river and the Yangtze river.These sections are developed on the limestone of the Triassic,and the lithology of the sections is relatively uniform,mainly composed of brown and yellow silty sand and sandy clay,containing a small amount of calcareous nodules.Soil weathering degree is weak,no obvious ancient weathering layer.According to the

关 键 词：长江三峡地区 巫山黄土 粒度 

分 类 号：P642.131[天文地球—工程地质学] P512.2[天文地球—地质矿产勘探]