陆相断陷盆地层序成因初探

层序成因初步分析表明，陆相断陷盆地的层序形成机制不是海（湖）平面变化，而是幕式构造沉降作用。二级构造旋回控制层序的发育，三级、四级旋回分别是准层序组；大多数准层序形成的主导控制因素、构造沉降新增沉积空间与同期供给或充填盆地的沉积物体积之间的对比关系，决定了准层序、准层序组和体系域的类型和特征。作为划分陆相断陷盆地各级层序的主要界面，如不整合面、沉积间断面等，其形成与构造作用有关。层序成因分析同时还揭示陆相断陷盆地的湖平面变化与海平面变化不同步及没有可比性。

GENESIS OF STRATIGRAPHIC SEQUENCE IN CONTINENTAL RIFT BASINS

A preliminary genesis analysis about a stratigraphic sequence showed that the development of sequence in confinental rift basins is just controlled by episode tectonic subsidence,and not sea/lake-level changes. The second order tectonic cycles control the development of sequences while the third and the forth order tectonic cycles are the main control factors of the development of parasequence sets and most parasequences respectively. The ratio between the new space added by tectonic subsidence and the volume of supplied or filled corresponding sediment determines the type and the characteristics of parasequences , parasequence sets and depositional systems tracts. The development of the main sequence surfaces,such as the unconformity and hiatus ,for dividing different order sequences in continental rift basins,is related to tectonic events. Moreover,the analysis of sequence genesis has also revealed that lake-level changes are not synchronized with or correlative with sea-level fluctuations.