准噶尔盆地南缘雀儿沟剖面白垩系地层特征及沉积环境

为适应目前准噶尔盆地南缘油气勘探的需要,选取研究区典型剖面——雀儿沟剖面开展白垩系地层特征及沉积环境研究。基于野外露头观察及薄片鉴定资料,结合地层划分对比及相标志,进行地层特征分析,将白垩系划分为下统吐谷鲁群清水河组、呼图壁河组、胜金口组、连木沁组和上统东沟组。根据岩性、粒度、颜色及原生沉积构造等对沉积环境进行系统分析,划分出辫状河、冲积扇、扇三角洲和湖泊4种沉积环境。研究区下白垩统发育2套沉积旋回,其中清水河组为一个完整的湖进、湖退旋回,发育辫状河、扇三角洲和湖相沉积;呼图壁河组、胜金口组和连木沁组表现为一个完整的湖进、湖退旋回,发育扇三角洲和湖相沉积。上白垩统东沟组表现为湖进旋回,发育辫状河和冲积扇沉积。研究结果表明,准噶尔盆地南缘白垩系具有良好的石油地质条件。

Formation characteristics and sedimentary environment analysis on Cretaceous of Queergou section,Junggar basin

In response to the need of exploration activity of southern margin in Junggar basin,knowledge of sedimentary environment of Cretaceous system is needed to be obtained,we studied the Queergou section,which is the representative section in the interest region.Based on the field survey observation and thin section analysis in laboratory,combined with the areal structure, the comparison of stratigraphic division and characteristic of sedimentary facies,we analyzed the character of layer and sedimentary facies.Results from comparison and division show that it is composed of the Qingshuihe,Hutubihe,Shengjinkou,Lianmuqin and Donggou formations.According to the comprehensive analyses of lithology,color,deposition texture and sedimentary structures, four kinds of sedimentary environments are identified,they are fluvial,alluvial fan,fan delta and lake.The sedimentary evolution indicates that two sedimentary cycles of lake ingression and lake transgression ever occurred in the low Cretaceous.The first transgression began and ended in Qingshuihe age.It graded into fluvial,fan delta and lake.The second transgression began in Hutubihe age and ended in Lianmuqin age.It graded into fan delta and lake.The half-cycle of lake retreating developed in Donggou age,and it includes fluvial and alluvial fan.The preliminary analysis shows that the conditions of hydrocarbon source rocks and reservoir rocks of the Permian in the study area are rather favorable.