现代浅水湖盆三角洲沉积砂体形态特征——以洞庭湖和鄱阳湖为例

Sandbody Shape of Modern Shallow Lake Basin Delta Sediments——By Taking Dongting Lake and Poyang Lake for Example

以Google Earth提供的卫星照片平台为基础,对现代洞庭湖和鄱阳湖河口沉积进行了描述,分析了砂体发育特征。洞庭湖东、西湖区环境差异明显,发育5处规模较大三角洲,三角洲特征各异,其中西洞庭三角洲沉积砂体最为发育。潘阳湖基本东西分隔,以西部湖区沉积为主,特别是赣江三角洲砂体面积占整个湖区面积的7成以上。两湖中现代浅水三角洲砂体有两种展布形式,一种是连片展布砂体,主要发育于西洞庭和西潘阳湖中,尤以赣江三角洲最为典型,而另一种以枝状孤立砂体为特征,以东洞庭草尾-蒿竹河三角洲和潘阳湖西河三角洲为代表。前者三角洲平原发育,砂体连片分布,主体成因为分流砂坝。后者枝状、条带状分布,不具备广阔的平原相带,主体是天然堤沉积。通过对其成因分析认为其形成主要受控于河道推进过程中的沉积稳定程度,而这可能与河流的沉积物构成及水量相关。

The deposition of river mouths in modern Dongting Lake and Poyang Lake were described based on satellite images provided by Google Earth,and the characteristics of sandstone development were analyzed.There existed great differences in the deposit between West and East Dongting Lake and 5 bigger deltas were developed,their characteristics were different,sandbodies were greatly grown in the west Dongting Dalta.Poyang Lake was separated from the east to west and the deposit was dominated in the west,and the Ganjiang Delta took the 70 percent of the total sandstone deposit.There were two kinds of distributive types of modern shallow delta sand-bodies,one was the continuous sandstone,which was mainly grown in the West Dongting Lake and West Poyang Lake,Ganjiang Delta was a typical one;and the other was isolated lace belt sandstone,represented by the Caowei-Haozhu Delta in Tongting Lake and Xihe Delta in Poyang Lake.The continuous sand-bodies are composed of mouth bar sandstone and wide delta plain.The isolated sand-bodies are composed of levee sandstone and a narrow delta plain.The formation of sand-bodies is controlled by the stabilization during river propagation,it possibly related with the grain size of sediments and water content.