准噶尔盆地彩南地区石树沟群地震层序划分与层序地层学解释

Division of Seismic Sequences and Interpretation on Sequence Stratigraphy of Shishugou Group, Cainan Area

从地震资料入手,根据某些古凸起部位石树沟群内部存在的削截、上超、下超等不整合反射,将彩南地区石树沟群划分为3个地震层序。通过区域追踪以及钻井和露头资料的综合分析,发现这3个地震层序分别与头屯河组、齐古组和喀拉扎组3个岩石地层单元相对应。头屯河组顶界的不整合系构造抬升剥蚀所形成,属构造成因,齐古组顶界的不整合系丘形侧积作用所形成,属沉积成因。地震相分析表明这3个层序（组）为3期物源来自北北东向克拉美丽山的洪积扇沉积,其地层发育和沉积相特征受构造、物源和古气候3大因素的控制。在地震资料所揭示出的石树沟群内部和顶界不整合面附近及某些丘形、透镜形沉积体中,存在多种可能的地层圈闭。

On the basis of seismic data, three seismic sequences are divided from Shishugou Group, Cainan Area. After correlating and tracing the reflection of sequence boundaries, combining it with the analysis of the outcrop and well logs, it is found that the three seismic sequences cor-respond to three stratigraphic formations, respectively: Toutunhe, Qigu and Kalaza formations. At some places of uplifts, the bottom of Qigu Formation is a structural unconformity. The three sequences (formations) represent three times deposition of alluvial fans which flowed from Kelameili Mountain in NNE direction. Their stratigraphic development and depositional character were controlled by three main factors: structural movement, source and paleoclimate. In Shishugou Group, some potential stratigraphic traps may exist nearby the unconformities and within some mound and lens-shaped depositional bodies revealed by the seismic data.