摘要： 下侏罗统三工河组是准噶尔盆地南部地区(南缘和腹部)的主要生产层段,但物源、沉积相类型、沉积体系分布演化及控制因素一直存在争议。综合运用露头、录井、岩心、测井及地震资料等,研究三工河组四级层序格架下物源、沉积体系类型、分布演化及控制因素。结果表明: 物源变化、古地貌演化、构造和古气候条件共同控制了准噶尔盆地南缘及腹部早侏罗世沉积环境格局及充填过程。准噶尔盆地早侏罗世处于相对稳定的构造环境,古气候相对湿润。准噶尔盆地南缘东段及腹部形成了宽缓的大面积汇水区,发育来自西部扎伊尔山、哈拉阿拉特山、东部克拉美丽山的毯式浅水辫状河三角洲,来自天山造山带的毯式浅水扇三角洲和毯式浅水辫状河三角洲2种沉积环境,可划分为5大沉积体系; 准噶尔盆地南缘西段为小而陡的汇水区,南侧发育来自天山的吉尔伯特式浅水扇三角洲,北侧发育来自扎伊尔山的吉尔伯特式浅水辫状河三角洲2种沉积环境,可划分为2大沉积体系; 受古气候、沉积基准面和沉积作用的控制,三工河组二段1砂组为低位体系域,沉积基准面低,三角洲向湖延伸较远,砂体分布最广,向湖粒度变细; 三工河组二段2砂组为湖侵体系域,三工河组一段为高位体系域,三角洲分布范围次之; 三工河组三段为高位体系域的早期沉积,以湖相沉积为主。

关键词: 沉积体系, 控制因素, 毯式浅水三角洲, 吉尔伯特式浅水三角洲, 三工河组, 准噶尔盆地

Abstract: The Sangonghe Formation is the main production unit of the southern Junggar Basin,but the provenance,sedimentary facies,and their controlling factors remain poorly resolved. In this paper,the 4th sequence-stratigraphic framework of the Sangonghe Formation was investigated based on outcrops,well logging,cores,and seismic data. The results suggest that the provenance change,the palaeogeomorphic evolution,the tectonic and palaeoclimate conditions controlled sedimentary patterns and filling process in the southern Junggar Basin during the Early Jurassic. The Junggar Basin formed under a relatively stable tectonic environment and relatively humid palaeoclimate in the Early Jurassic. There are two sedimentary facies and five sedimentary systems in the central and the eastern of the southern Junggar that was a wide and gentle catchment area in Early Jurassic. One facies is shoal-water baided-river delta,which is divided into four sedimentary systems,respectively,from the Zaire Mountain to the west of Junggar Basin,Halarat Mountain to the northwest of Junggar Basin,Kelamili Mountain to the east of Junggar Basin and Tanshan Mountain to the south of Junggar Basin. The other facies is shoal-water fan delta from the Tianshan Mountain to the south of Junggar Basin. There are two sedimentary facies and two sedimentary systems in the western of the southern Junggar Basin that was a small and sharp catchment area in the Early Jurassic. One faices is Gilbertian shallow-water fan delta from the Tianshan Mountain to the south of Junggar Basin,and the other is shoal-water braided-river delta from the Zaire Mountain to the western Junggar Basin. Controlled by palaeoclimate and depositional base level,the interval 1 of Member 2 of Lower Jurassic Sanggonghe Formation is a lowstand system tract,and the depositional base level is low. The deltas extended further forward,and resulted in sandbodies distributed widely and fining forward. The interval 2 of Member 2 of Lower Jurassic Sanggonghe Formation is a transgressive system tract,and the Member 1 of Lower Jurassic Sanggonghe Formation is a highstand system tract. The range of their deltas distributed smaller than those of the submember 2. Shore-shallow lacustrine deposits were dominant in the Member 1,which were the early sediment of a highstand system tract.

Key words: depositional system, controlling factor, shoal-water profile delta, Gilbertian shallow-water delta, Sangonghe Formation, Junggar Basin

中图分类号: 

• P531