断陷湖盆沉积作用的基本方程及其应用

The basic equation of sedimentation and its application in rift lake basin

湖盆沉积作用受气候、构造、沉积物供给条件、海平面升降变化等因素控制 ,将水深变化 (水深加深为正值 ,水深变浅为负值 )与盆地基底的沉降幅度 (上升为负值 ,下降为正值 )、绝对湖平面垂直变化 (上升为正值 ,下降为负值 )和沉积物厚度的关系浓缩为一个简单的沉积作用基本方程 ,其中各参数取某时间段内的变化值。结合对该基本方程及其各参数含义的讨论 ,综合解释湖盆层序界面的形成机制和湖退、湖进作用的原理。气候变化、构造抬升、断陷盆地中差异沉降运动等因素是控制层序界面形成的三大成因机制 ;根据湖退现象的作用机制 ,湖盆中也存在正常湖退和强制湖退两种类型 ,沉积物过量充填引起湖盆发生正常湖退作用 ,相对湖平面下降导致湖盆发生强制性湖退作用。图 4参

Sedimentation of lake basin is controlled by the following factors: climate, structure, sediment supply, sea level change and so on. Change of water depth and subsidence amount of the lake basin basement, change of the absolute lake level and sedimentary thickness are considered into a simple equation (called as the basic equation of sedimentation), and every parameter stands for the change value during the period of Δ t . Combining with the discussion of the sedimentary basic equation and the signification of every parameter, the forming mechanism of sequence boundary and the principles of lake regression and lake transgression were interpreted. The formation of the sequence boundary was controlled by climate changing, structural lifting and differential vibratory movement which are the three forming mechanisms of the sequence boundary. Based on the forming mechanisms, the lake regression can be further divided into two types: normal lake regression and forced lake regression. The normal lake regression was caused by excessive filling of sediment, and forced lake regression by falling of relative lake level.