西北地区侏罗系盆地典型充填序列

西北地区是指贺兰山以西的广阔地域。三叠纪末，形成了一种高差较小，以低山丘陵为主要特征的地貌，分布着一系列大小不同的陆相沉积盆地。盆地的充填序列可以理解为盆地发育的整个垂向上的沉积序列，这个序列由若干套岩性组合构成，并按一定顺序出现。沉积体系的交替反映了构造演化的阶段性、沉降和沉积的过程及两者之间的定量关系。本文选取了西北地区不同构造部位侏罗系沉积剖面进行充填学分析，划分出主要的充填序列类型及沉积模式，清楚地看到西北地区不同构造单元内的盆地在垂向沉积序列上的共性和差异。

Typical Fill Sequences in Jurassic Basins in the Northwest Region of China

The northwest region refers to the vast tracts west of the Helan Mountains in China.At the end of the Triassic,a low mountain_hill_dominated geomorphology with a relatively small elevation difference was formed.There,a series of continental sedimentary basins of varying sizes are distributed.The fill sequence of a basin may be understood as an entirely vertical depositonal sequence developed in the basin.This sequence is made up of several rock associations which appear in a certain order.The alternation of sedimentary systems displays the stages of tectonic evolution and processes of subsidence and deposition and their quantitative relationship.Jurassic sedimentary sections in different tectonic positions of the northwest region are selected in the paper to make an analysis of the fills and determine the major fill sequence types and the sedimentary model.It may been found clearly that there are both general characters and differences in the vertical depositional sequerrces of the basins in different tectonic units of the northwest region of China.