Sedimentary characteristics and evolution model of the Early-Middle Jurassic on the south of Fukang Sag in eastern Junggar Basin

The Jurassic in the eastern Junggar Basin is not only an important reservoir stratum, but also a main hydrocarbon source layer, so that it has abundant oil and gas resources. The measured section named after its location is called Ganhezi section, which is in the southern of Fukang Sag of eastern Junggar Basin. Ganhezi section consists of the successive Early-Middle Jurassic. By means of observing and describing the Ganhezi section elaborately, and according to the measured data of rock types, sedimentary structure, rock color and grain size probability accumulative curves, the author analyses the sedimentary facies of the Early-Middle Jurassic in detail. The research of sedimentary facies indicates that Badaowan Formation comprises fluvial facies, shallow lacustrine subfacies and delta front subfacies; Sangonghe Formation consists of braided river facies and shallow lacustrine subfacies; Xishanyao Formation comprises braided river facies and fluvial facies. Based on sedimentary characteristics and the variation of sedimentary facies, an evolutionary model with fluvial facies-lacustrine facies-delta facies-lacustrine facies-braided river facies-lacustrine facies-braided river facies-fluvial facies integrated is proposed. Paleocurrent measurements show that the main paleocurrent direction of Badaowan Formation and Sangonghe Formation were SSW-SW, and according to the Walther's sedimentary facies sequence law, the provenance of Badaowan Formation and Sangonghe Formation were Kelameili Mountain and the region of Boegda Mountain was subaqueous deposit. The paleocurrent direction of Xishanyao Formation was NW-NWW, which indicates that the provenance was in the east and southeast of the study area. The author speculates that the Beisantai and eastern region of Bogeda Mountain had uplifted preliminarily and the tectonic framework of the eastern Junggar Basin had a great change from Middle Jurassic. © 2015, Science Press. All right reserved.