准噶尔盆地西北缘侏罗系展布与层序地层格架特征

Distribution and sequence stratigraphic framework of the Jurassic strata on the northwestern margin of the Junggar Basin

准噶尔盆地侏罗系层序级别的划分,受西北缘主断裂构造活动的影响,主断裂下盘侏罗系地层较厚,而在断裂带上盘较薄,部分地区缺失。根据研究区内的钻井、测井和地震资料,应用层序地层学理论与研究方法将准噶尔盆地西北缘侏罗系划分出2个构造层序(JTS1,JTS2)、7个层序(I—VII)和10个体系域。煤的发育在层序划分中具有重要的意义。准噶尔盆地西北缘侏罗系层序地层的控制因素包括构造运动、物源供应、湖平面升降、气候条件,其中构造运动和湖平面升降是控制层序发育的主要因素。

The sequences in Junggar basin were influenced by the major fault on the northwestern margin. The Jurassic is relatively thick in the footwall of the major fault, but is relatively thin or even absent in the hanging wall. However, based on available drilling, log, and seismic data in the study area, this paper recognized 2 struc-tural sequences （JTS1 ,JTS2 ） , 7 sequences （I-Ⅶ） , and 10 system tracts in the Jurassic by employing classical sequence stratigraphy theory and approaches. It suggests that the occurrence of coal layers bears important significance in sequence demarcation and that the controlling factors for the Jurassic sequence stratigraphy on the northwestern margin of Junggar basin include tectonic movement, sediment supply, lake level rise and fall, and climate. Among them, the tectonic movement and lake level rise and fall are considered the most important.