准噶尔盆地三个泉地区下白垩统沉积相特征

Sedimentary facies of lower cretaceous in Sangequan area of Junggar Basin

在系统观察岩心和地层划分对比的基础上 ,从单井相分析入手 ,结合地震、测井、古生物、分析化验资料和岩相古地理条件研究成果 ,建立了准噶尔盆地三个泉地区下白垩统各时期岩相古地理格架 ,阐明了沉积环境变迁、沉积发展史、沉积演化规律和沉积演化控制因素。研究结果表明 ,受晚侏罗世构造运动的影响 ,三个泉地区低幅度隆起基本被夷平 ,湖水向南退出 ,在北高南低的古地形背景下 ,早白垩世发育炎热干旱半干旱气候条件下的河流和浅水三角洲沉积。下白垩统清水河组发育辫状河沉积 ,由于河道的频繁迁移 ,辫状河道沉积在纵向上相互切割叠置 ,形成了厚度较大、延伸距离较远的板状砂体 ,向上泛滥平原沉积增多 ;呼图壁河组以朵叶状三角洲、浅湖和滩坝沉积为特征 ;胜金口组发育滨浅湖和滩坝沉积 ;在连木沁组沉积时期 ,湖水向南迅速退出研究区 。

According to core observation and stratigraphic division and correlation, the individual-well sedimentary facies was analyzed. The numerous data of seismic, logging, paleotology and the analysis results of the lithofacies palegeographic conditions have been used to establish the frameworks of the lithofacies paleography of lower Cretaceous in Sangequan area of Junggar Basin. The sedimentation development, variation of sedimentary environment, sedimentation variation laws and control factors of sedimentation development were investigated. Under the impact of the Late Jurassic movement, the Sangequan lower uplift was raised to the ground, and the lake water recessed towards south. There developed fluvial and shallow-delta deposits accumulated under the hot and dry-semiarid climate in the early Cretaceous. Braided channel deposit was truncated and stacked in Qingshuihe Formation of the lower Cretaceous. The frequent migration of braided river course resulted in the heavy recurrent deposition of braided channel and formed tabular sand with big thickness and far extension distance. The flood plain deposits increased upward. The deposits of lobate delta, shallow lake and beach and/or bar were developed in Hutubihe Formation of the early Cretaceous. The coast shallow lake deposits and beach or bar deposit were developed in Shengjinkou Formation of the early Cretaceous. The meandering river deposit backslided from the studied area largely in the deposition period of Lianmuxing Formation in the early Cretaceous. The meandering stream was widely developed.