陆相盆地充填层序的类型--以辽西地区中生代盆地为例

辽西地区在中生代发育了各种类型的陆相盆地，形成各种类型的地层。在按层序定义识别出不同盆地、不同时间的层序基础上，根据地质作用营力（如水、风和火成作用）、沉积介质与地质环境的特点将该区盆地充填的层序划分为湖盆层序、冲积层序、沙漠层序和火山层序等类型。对于不同类型的层序不仅其层序内部组成各异而且其层序控制因素也不尽相同。湖盆层序是指在湖盆地内由沉积作用形成的一类层序，表现为随湖水面的升降变化沉积体系或体系域在时空上的变化。一个完整发育的层序可以反映出一个水侵-水退的湖水变化周期。冲积层序是指在流域盆地中以冲积沉积作用为主而形成的一类层序，其不明显地受蓄水面的控制，但受潜水面的影响和地形及侵蚀基准面的控制。沙漠层序是指在风介质的条件下以沙漠沉积为主体的一类层序。火山层序是指由于火山作用导致的火山物质（包括沉积物）在盆地内的充填所形成的层序，通常发育在断陷盆地的早期阶段，由火山岩、火山碎屑岩、凝灰岩和沉积岩所构成。在辽西地区中生代盆地和各类型层序的控制因素中，构造因素是第一位的，表现在层序界因多为构造界面，如区域角度不整合面、平行不整合面以及构造转换面等。但各类型层序的具体控制因素是有差异的。

Types of Filling Sequences in the Continental Basins-- Examples from Mesozoic Basins,Western Liaoning Province

Some kinds of continental basins were formed during the Mesozoic in the western Liaoning Province, in which the varied strata occurred. On the basis of recongnizing the sequences of different basins in different times and according to the sequence defination, the sequence types including lake basin sequence, alluvial sequence, desert sequence and volcanic sequence were given through the analysis of geological agents (such as water, wind and igneous process), sedimentary media and geological environments. The internal assemblages of different sequences are different and their controlling factors are not the same. Lake basin sequence is formed through and sedimentation, showing the changes of the sedimentary systems or system tracts in time and space with the lake level variation. A whole sequence may reflct the cycle of transgressive regressive processes of the lake. Alluvial sequence developes through alluviation in a river basin. The storing water level does not control it directly, but it is influenced by groundwater level and controlled by topography and erosional basement level. Desert sequence is a kind of sequence composed of desert sediments under condition of wind medium. Volcanic sequence composed of volcanic, pyroclastic, tuff and sedimentary rocks is formed by the filling of volcanic substances(including sediments) in a basin during the time of volcanic activities. Of the controlling factors of the sequences in the Mesozoic basins, the western Liaoning Province, the tectonics was the most dominated. Most of the sdquence boundaries were tectonic surfaces, such as regional angular uncomformaties, paralell unconformaties and tectonic transform surfaces. However, the controlling factors among different types of the sequences were different with each other.