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长江三峡屈原镇土状堆积的成因及地质环境意义
投稿时间:2019-03-21  修订日期:2019-04-16  点此下载全文
引用本文:
DOI:10.19762/j.cnki.dizhixuebao.2019147
摘要点击次数: 116
全文下载次数: 150
作者单位E-mail
张玉芬 中国地质大学地球物理与空间信息学院 zhangyfcug@163.com 
李长安 中国地质大学地球科学学院  
孙习林 中国地质大学地球科学学院  
魏传义 中国地质大学地球科学学院  
李亚伟 中国地质大学地球科学学院  
基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目)
中文摘要:三峡地区的第四纪土状堆积物的成因研究对地质灾害(滑坡等)、灾害事件(堵江等)、水土流失和气候变化等具有重要意义。位于兵书宝剑峡下游新滩大滑坡的东侧势大岭剖面发育了一套近5m厚的灰褐色亚黏土,是一处新发现的土状堆积物。本研究在野外剖面测量和观察的基础上,通过系统的粒度分析对其成因进行了研究。结果表明:势大岭剖面上部土状堆积物(剖面中第1层)主要由<50μm的颗粒组成;>50μm的砂粒级以上颗粒平均含量13.14%;作为风尘 “基本粒组”的10-50μm的粗粉砂平均含量达50%,为众数粒组。粒度参数、频率曲线及粒度象(C-M、L-M、A-M图)等分析均显示为风积成因。势大岭剖面中、下部(剖面中第2和3层)属河流冲积成因,是由河床相与河漫滩相组成的二元结构。年代学研究及与前人河流阶地测年资料对比表明,势大岭剖面形成于中更新世末至晚更新世,上部的土状堆积物形成于距今110—60 Ka。通过与长江流域同期风积物的对比,认为势大岭剖面上部的土状堆积物属于下蜀黄土,并为下蜀黄土的西部边界。位于西陵峡西段的兵书宝剑峡是下蜀黄土与具有北方黄土特征的巫山黄土的分界,鉴于两者的区别,推测兵书宝剑峡至少在晚更新世可能在地貌上具有区域气候环境划分的意义,对此应予以关注。
中文关键词:长江三峡  土状堆积物  粒度特征  下蜀黄土
 
Sediment Formation of Quyuan Town in the Three Gorges Valley and its Implications for the Geo-environment Division
Author NameAffiliationE-mail
ZHANG Yufen Institute of Geophysics and Geomatics,China University of Geosciences,Wuhan zhangyfcug@163.com 
LI Changan School of Earth Sciences,China University of Geosciences,Wuhan  
Sun Xilin School of Earth Sciences,China University of Geosciences  
WEI Chuanyi School of Earth Sciences,China University of Geosciences  
Li Yawei School of Earth Sciences,China University of Geosciences  
Abstract:Formation of Quaternary sediment in the Three Gorges area is critical important for studying of the geological disasters, disaster events, soil erosion and climate changes. Shidaling section, nearly 5m sediment sequence deposited in eastern Xintan landslide, downstream of the Bingshubaojian Gorges, is discovered in recent geological survey. In this paper, based on the field investigation and profile measurement, combined with systematic grain size analysis, sediment formation process of the Shidaling section was studied. The results show that: 1) upper sediment of the Shidaling section is mainly composed of size fraction of < 50μm, average content of size fraction of > 50μm is 13.14% while that of size fraction of between 10 and 50μm is 50%, which is the basis grain size fraction of the aeolian sediments; 2) Grain size parameters, frequency curves and grain size distribution results (C-M、L-M and A-M figures) indicate that the upper Shidaling section is aeolian deposition while middle and lower Shidaling section is fluvial sediment, which showing a typical positive dual-texture. Chronology results and comparison with dating results of terrace reveal that the Shidaling section formed between late middle-Pleistocene and late Pleistocene, the upper section formed at 110-60 ka B.P.. Comparison with the contemporaneity sediment of the Yangtze River Basin, we propose that upper Shidaling section is Xiashu Loess, and is the western boundary of the Xiashu Loess. All those results demonstrate that the Bingshubaojian Gorges is the division of the Xiashu loess and Wushan loess, which is similar to the loess in Chinese Loess Plateau. Geomorphological speaking, the Bingshubaojian Gorges is a crucial area for division studying of regional climate and geo-environment. In the future, the section should be paid more and more attention.
keywords:The Yangtze River  Three Gorges  eolian sediment  fluvial sediment  grain size characteristic  Xiashu Loess
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