Indian Journal of Geo Marine Sciences Vol. 47 (12), December 2018, pp. 2353-2368 Research Article Evolution and characteristics of sedimentary systems during fault-depressed transition in Songliao Basin—Case study of the Denglouku formation in the southeast uplift region Zhan-dong Li 1,2 , Chun-xu Li 2 , Wei Li 2 , Li Li 3* , Yi-kun Liu 2 &Zheng-meng Hou 4 1 State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100010, China 2 College of Petroleum Engineering Institute, Northeast Petroleum University, Daqing 163318, China 3 Department of Earth Sciences, National Taiwan Normal University, Taipei 11677, Taiwan 4 Energy Research Institute of the Lower Saxon, Clausthal University of Technology, 38640 Goslar Germany [E-mail: 80344003S@ntnu.edu.tw] Received 30 November 2017; revised 02 May 2018 This study analyzes the sedimentary characteristics and evolution of Denglouku formation. There are 5 types of subfacies developed: alluvial fan, fan delta, braided river, braided river delta and lacustrine facies. Influenced by tectonic activity, the sedimentary facies types are different in different sedimentary periods. In the early stage of the transition period named D1 member period, the deposition is significantly controlled by the fault depression, resulting in rapid unloading of the sediments. Five large-scale divided faulted depressions and two small faulted depressions have been developed. During the late stage of the transition period named D2 member period, the unified sediment unloading area is formed, and the lake area expanded, which developed alluvial fan, fan delta, braided river, braided river delta and lacustrine deposits. Taking the community of the floodplain and lacustrine contact zone as a boundary, the western part mainly developed alluvial fan and braided river sedimentary system from the provenance highland in the western and northern, the east part mainly developed lacustrine facies massively. Among them, the fan delta front and braided delta front subfacies are the main enrichment reservoirs for oil and gas, which is the favorable subfacies of oil and gas exploration in the future. [Keywords: Songliao Basin, the southeast uplift region, Cretaceous, Denglouku formation, Sedimentary facies.] Introduction The southeast uplift region is a first-order tectonic unit in southern Songliao basin. Due to the disproportionate and generally low exploration degree, the overall understanding of the southeast uplift region has been limited. Some researchers have studied the aspects of sequence stratigraphy 1-4 , thermal evolution history, structural characteristics and reservoir and summarized many regularities 5-12 . In reality, few research reports can be touched regarding to the evolution process and characteristics of sedimentary systems in the Denglouku formation of the southeast uplift region. However, in recent years, it has been proved by the exploration practice that there are various types of reservoirs in the Denglouku formation, and more industrial oil wells and stripper wells have been developed, which indicates great exploration potential 13-17 . On the basis of previous studies, combining analyses of seismic data, core samples, logging data, and laboratory tests, the authors provide the detailed description of the characteristics of sedimentary systems and evolution process in the Denglouku formation, which are of great significance to benefit in the exploration and development of the reservoir formation in the southeast uplift region. Materials and Methods The southeast uplift region, an extremely special and important first-order tectonic unit, characterized by typical rift-depression dual structure, is located in the southern Songliao Basin, with about 3.6 × 10 4 km 2 in area. The study area 18 , composed of twelve second- order tectonic units with different scale (Fig. 1), extends in north-east trending; the southern part in this area is bounded by Jilin oil field, the western part is adjacent to the central depression, the southwest uplift is in the region of Songliao Basin, and the eastern is neighboring to the Yitong basin. The tectonic evolution of the basin went through 5 stages 19-22 , including the faulted sedimentary stage from Shahezi to Yingcheng formation, the fault-