中国东部第三系典型断陷盆地幕式构造旋回及层序地层特征

Episodic tectonic cycles and sequence pattern of the Tertiary rifted basins of East China

应用盆地充填记录、盆地构造特征和盆地沉降史等信息,揭示了中国东部第三纪典型断陷盆地的幕式构造演化过程。幕式构造演化是断陷盆地层序形成和演化的关键因素,不同序次的构造幕控制不同序次的层序地层单元的形成和演化。中国东部古近系裂陷期经历了4个发育阶段,相应形成了4个二级层序。其中,强烈裂陷沉降幕发育深湖盆型层序,初始和晚期裂陷幕发育浅湖和河流-浅湖型层序。而新近系拗陷期可划分为2个阶段,形成2个二级层序,以河流和三角洲-浅湖型层序为特征。受裂陷幕控制的二级层序在中国东部各断陷盆地中具有很好的可对比性,但受低级幕式伸展事件控制的三级层序在不同盆地中具有明显的差异性。

The episodic rifting processes of the Tertiary representative rifted basins in East China were revealed on the basis of the basin filling records, tectonic framework and subsidence history. The episodic tectonic change controlled the formation and evolution of sequence in the rifted basin. The formation and evolution of different stratigraphic units in different sequences were controlled dominantly by the different scales of tectonic episodes. The Eogene rifted basins in East China experianced four rifting episodes, and four secondary sequences were formed correspondingly. In intensively rifting subsidence episodes, some deep lacustrine basin sequences were usually observed, while the shallow lacustrine and fluvial basin sequences commonly formed during the initial and final rifting episodes. The depression stage in the Neozoic included two episodes, and two secondary sequences were correspondingly formed. There mainly observed the fluvial and delta-shallow lacustrine sequences. The secondary sequences of rifted basins in East China controlled by rifting episodes had good correlation, and the third sequences controlled by the low episodic extended events had distinct diversity.