地理科学 ›› 2016, Vol. 36 ›› Issue (6): 951-958.doi: 10.13249/j.cnki.sgs.2016.06.019

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青弋江上游泾县段阶地砾石层砾组结构及其沉积环境研究

胡春生1,2(), 吴立1,2, 杨立辉1,2   

  1. 1.安徽师范大学国土资源与旅游学院,安徽 芜湖 241000
    2.安徽自然灾害过程与防控研究省级实验室,安徽 芜湖 241000
  • 收稿日期:2015-07-13 修回日期:2015-10-14 出版日期:2016-10-20 发布日期:2016-10-20
  • 作者简介:

    作者简介:胡春生(1978-),男,安徽无为人,副教授,主要从事河流地貌研究。E-mail:huchsh03@163.com

  • 基金资助:
    国家自然科学基金项目(41301011,41201008)资助

Gravel Fabric and Sedimentary Environment of Terrace Gravel Layers of the Upper Qingyijiang River at Jingxian County

Chunsheng Hu1,2(), Li Wu1,2, Lihui Yang1,2   

  1. 1.College of Territorial Resources and Tourism, Anhui Normal University, Wuhu 241000, Anhui, China
    2.Anhui Key Laboratory of Natural Disaster Process and Prevetion, Wuhu 241000, Anhui, China
  • Received:2015-07-13 Revised:2015-10-14 Online:2016-10-20 Published:2016-10-20
  • Supported by:
    National Nature Science Foundation of China(41301011,41201008)

摘要:

通过对青弋江上游泾县段阶地砾石层进行砾组分析,讨论阶地砾石层的沉积环境及其对青弋江发育的启示。结果表明:砾径以中砾和粗砾为主,砾石沉积时水动力条件较强,流速基本为2 m/s左右,最大可达到3.5 m/s,特别是T3砾石层形成时期;砾向在T3和T2砾石层形成时期分别为南南西(SSW)和南西西(SWW)方向,古流向变化不大,呈自南而北的基本流向;砾态以次圆和圆为主,其总含量超过70%,较高的磨圆度暗示砾石经历了较远距离的搬运;砾性主要有石英砂岩、砂岩、脉石英和石英岩,其总含量达到90%以上,且砾石物源区变化不显著;T2砾石层和T1砾石层是典型的河流沉积,而T3砾石层可能是河流沉积和泥石流沉积叠加作用的产物,并且T3砾石层的沉积特征对于分析古青弋江的发育有一定的启示作用。

关键词: 青弋江, 阶地, 砾石层, 砾组分析, 泾县

Abstract:

Through the analysis of the gravel fabric of terrace gravel layers to the upper Qingyijiang River at Jingxian County, this article tries to discuss the sedimentary environments of terrace gravel layers and its indicative effect on the development of the Qingyijiang River at Jingxian County. The Qingyijiang River Basin is located in southern of Anhui Province, issuing from the northern fringe of Huangshan Mountain, is an important tributary of lower reaches of the Yangtze River. Field investigation focuses on a natural outcrop along the upper reaches of the Qingyijiang River at Jingxian County, where a well-preserved sequence of three gravel layers of river terraces is present. These gravel layers are generally 4-6 m in thickness, overlying by about 2-5 m red clay. The results show that: 1) The gravels are mainly medium and coarse in diameter, and the hydrodynamic conditions are strong in the formation periods of terrace gravel layers when the mean velocity of river is about 2 m/s while the maximum velocity can be up to 3.5 m/s, especially in the formation periods of T3 terrace gravel layer; 2) The gravel orientations in T3 terrace gravel layer and T2 terrace gravel layer are 191° and 250°, pointing to the SSW direction and SWW direction, respectively. The paleocurrent of the Qingyijiang River at Jingxian County shows little change from the formation period of T3 terrace gravel layer to that of T2 terrace gravel layer, being similar to the present current which flows from south to north; 3) The gravels are mainly sub-round or round in shape, and the total content of such gravels is more than 70% in each terrace gravel layer. The roundness of terrace gravel layers is good, implying that these gravels should be transported over a long distance from its provenances; 4) The terrace gravel layers contain mainly quartz sandstone, sandstone, vein quartz and quartzite, and the total content of such gravels is up to 90% in each terrace gravel layer, showing that the change of the provenances is not significant; 5) The gravel layers of T2 terrace and T1 terrace are typical fluvial sediments, while the gravel layer of T3 terrace might be a product of the superimposition between the debris flow deposit and river deposit, and the sedimentary characteristics of the T3 terrace gravel layer might potentially has some indicating functions on the analysis of the development of the Qingyijiang River to some extent.

Key words: the Qingyijiang River, river terrace, gravel layer, gravel fabric analysis, Jingxian County

中图分类号: 

  • P931.1