印尼西纳土纳盆地Muda组河流体系分析

Fluvial System Analysis of Muda Formation in West Natuna Basin,Indonesia

印尼西纳土纳盆地更新世河流体系发育,以地震剖面和切片资料为基础,在盆地内K区块Muda组上部的沉积中识别出了近南北向的辫状河、东西向曲流河和高弯度分流河道三种河流类型。基于河流的切割关系,判断辫状河发育最早,曲流河次之,分流河道最晚。河流类型的演化反映了一个相对海平面上升的过程;早、中期河流方向的改变反映了相对海平面上升明显受构造作用控制。此外,中期曲流河和低弯度河流共存的现象,说明河流沉积还可能受坡度等其他因素的影响。

The fluvial systems were well developed in West Natuna basin of Indonesia. Based on analysis of seismic cross lines and couples of time slices,three fluvial types are identified in the Pleistocene Muda formation.The three types include braided rivers with a south to north flow direction,meandering river and high sinuous distributary channels with a west to east flow direction. According to the cutting relationship,it is inferred that the braided rivers formed early and the distributaries formed late; the fluvial type change reflects the relative seal-level rise,and the rise was controlled by tectonics obviously which was documented by flow direction change. Besides,the coexistence of braided and meander systems reflects the fluvial style was controlled by other factors such as slope and so on.