Lithofacies of Volcanic Rocks from Zhongguai Swell to District-5 and District-8 in Northwestern Margin of Junggar Basin
The core observation,slices appraisal,well-logging and logging data analysis are conducted for study of volcanic lithologies of Carboniferous and Permian from Zhongguai swell to District-5 and District-8 in northwestern margin of Junggar basin,combining with seismic data interpretation.On the basis of single well facies and section facies analyses,the plane distribution map of lithofacies of Carboniferous and sub-group of Jiamuhe formation of Permian is plotted.The Carboniferous in this area is dominated by volcanic rocks,with some andesites in the northeast,central and southwest;tuff in vast east area and the south,volcanic-sedimentary rocks in the southwest,these multi-rocks in the northwest,and volcanic breccia and basalt scattered near the west.The sub-group of Jiamuhe is also divided into two sections,from bottom to top,the rocks has some continuity with Carboniferous,but the lithofacies of upper section shows increase of andesite and volcanic-sedimentary rocks,and decrease of basalt and tuff,which may owing to volcanic activity tending to diminish and cease.