Sequence Stratigraphy and Sedimentary System Analysis of Nantun Group in Huhehu Depression in Hailaer Basin

Key words: 
• Huhehu Depression

Abstract: Based on the theory of sequence stratigraphy, sequence stratigraphy framework of Nantun group in Huhehu Depression is established in this paper by comprehensively research of cores, logging data and seismic data. Nantu group in Huhehu Depression is divided into 2 3rdorder sequences:SQ1 sequence is equal to the first stage of Nantu group, and SQ2 is equal to the second stage of Nantun group. Neither sequences develops completely, which is composed of low stand system, transgressive system tract and high stand system. According to the characteristics of divide sequence development of target strate in researched area, and based on the division and comparison of sequence formation unit, this paper studies on sedimentary types and system, determined that fan delta, braided river delta, sublacustrine, lake and so on are very development. SQ1 sequence mainly develops braided river delta in the north of basin, and fan delta in the south of basin. SQ1 sequence mainly develops braided river delta in gentle slope belt, and fan delta in steep slope in local area. Compared with SQ1 sequence, SQ2 develops swamp facies. Comprehensive analysis of sedimentary characteristics and evolution law, this paper points out that sedimentary sand bodies in the south of Huhehu Depression is the favourable exploring area.