摘要
通过综述国内外分支河流体系(DFS)的研究进展,总结了DFS的地貌特征和主要类型,并探讨了DFS形成和发育的控制因素。研究结果表明:(1)DFS不是新的或者特殊的河道类型,而是多种河道有规律的集合,地貌特征表现为水系网络从一点呈放射状展布,多种河型共同发育,河道几何形态变化大,沉积环境包括河道和河道间区域,沉积体系复杂;主要类型包括冲积扇、河流扇和巨型扇。(2)以DFS半径为关键指标,面积和坡度为辅助指标将DFS分为小型(冲积扇)、大型(河流扇)和巨型(巨型扇),小型DFS扇体半径小于30 km,面积小于100 km2,坡度大于1.0°;大型DFS半径为30~100 km,面积为100~1 000 km2,坡度小于1.0°;巨型DFS扇体半径大于100 km,面积大于1 000 km2,坡度小于0.5°,3种类型的分布范围有一定的交叉和重复,还需结合DFS的沉积水动力过程和沉积特征进行判别。(3)构造背景和气候是控制DFS形成与分布的最根本因素;流域面积、母岩性质直接影响DFS中沉积物供给总量、供给速率及成分和结构;地形坡度作为间接因素,与河流流量、流速等自生因素相结合,控制河道形态以及河道的分汊和决口,进而控制了DFS表面的沉积环境和沉积相分布。
Based on the research progress of distributive fluvial system(DFS),the geomorphic characteristics and main types of DFS were summarized,and the controlling factors of the formation and development of DFS were discussed.The results show that:(1)DFS is not a new or special river channel type,but a regular collection of multiple river channels.The geomorphic characteristics are shown as follows:the river network is radially distributed from one-point,various types of rivers develop together,the geometric shape of the river channel changes greatly,the sedimentary environment includes river channel and interchannel,and the sedimentary system is complex.The main types include alluvial fan,fluvial fan and megafan.(2)Based on DFS radius,area and their surface slope,DFS can be divided into three types as microDFS,macroDFS and megaDFS.The micro DFS,i.e.,alluvial fan,with a radius of less than 30 km,an area of less than 100 km2 and a slope of greater than 1.0°.The macroDFS is called fluvial fan,with radius greater than 30 km but less than 100 km,their area is greater than 100 km2 but less than 1000 km2,and slope is less than 1.0°.The megaDFS is megafan,which has a radius of greater than 100 km,an area of greater than 1000 km2 and a slope of less than 0.5°.The distribution ranges of the three types have certain overlap and repetition.It is also necessary to distinguish them by combining the hydrodynamic process and sedimentary characteristics of DFS.(3)Tectonic and climate are the most fundamental factors controlling the formation and distribution of DFS.Basin area and provenance may influence the total sediment supply and sediments composition of the depositional system.As an indirect factor,DFS slope may control the channel morphology and the bifurcation and crevasse of the channel together with channel flow and velocity,thus control the sedimentary environment and depositional facies distribution of the DFS.
作者
张昌民
张祥辉
Adrian J.Hartley
冯文杰
尹太举
尹艳树
朱锐
ZHANG Changmin;ZHANG Xianghui;ADRIAN J.Hartley;FENG Wenjie;YIN Taiju;YIN Yanshu;ZHU Rui(School of Geosciences,Yangtze University,Wuhan 430100,China;School of Geosciences,University of Aberdeen,Aberdeen AB243UE,UK)
出处
《岩性油气藏》
CAS
CSCD
北大核心
2023年第4期1-15,共15页
Lithologic Reservoirs
基金
国家自然科学基金重点项目“分支河流体系沉积模式与储层定量预测模型”(编号:42130813)资助。
关键词
分支河流体系
冲积扇
河流扇
巨型扇
辫状河
曲流河
扇体半径
distributive fluvial system
alluvial fan
fluvial fan
megafan
braided river
meandering stream
fan radius
