高弯曲与低弯曲河流比较沉积学研究--以长江上、下荆江段为例

以长江上、下荆江河段为例,运用比较沉积学的方法阐述了高弯曲流河与低弯曲流河的沉积单元及沉积特征。由于河流特性、流量及河流边界条件的不同,①虽然上、下荆江都发育了大量的点坝沉积,但在形态、分布位置、成熟度、粒度分布、沉积构造、剖面结构、微地貌特征等七个方面存在明显差别;②虽然上、下荆江都发育有江心洲 (心滩 ),但是其成因、规模、演化规律及沉积结构均不同;③决口扇沉积仅仅发育在上荆江河段,且两岸发育程度几乎均等,下荆江不发育决口扇沉积;④牛轭湖沉积仅发育在下荆江,而且主要分布于下荆江北岸。

Study of Comparing Sedimentology in High-sinuosity River and Low-sinuosity River

High-sinuosity river are low-sinuosity river aye two chief meandering r ivers.Taking Jingjiang river for example,the article expounds sedimentary unit and chara cteristic of two different kinds of meandering river with comparing sedimentolog y me thod.Because of difference in river nature,flow and boundary condition,①up and down stream of Jing Jiang take the shape of point bar,but the disparities exist in shape,distributive spot,maturity,grain size,sedimentary structure,s e ction texture,micro-morphologic unit.②many river islands exist in up an d down stream of Jingjiang river,but their cause of formation,scale,evolution nat ure an d sedimentary texture are different,③crevasse splay is only formed in up strea m of Jingjiang river and development degree is within equality two banks.The dow n stream of Jingjiang river and development degree is within equality two banks.The dow n stream of Jingjiang river don't exist crevasse splay.④ox-bow lakes exist only in d own st ream of Jingjiang river and northern bank is mainly distributive spot of ox-bow lake.