海拉尔盆地呼和湖凹陷南屯组层序地层与沉积体系分析

以层序地层学理论为指导，充分利用岩心、测井、地震等资料，依据层序界面反射特征，建立了海拉尔盆地呼和湖凹陷南屯组层序地层格架，将南屯组划分为两个三级层序:层序Sq1相当于南屯组一段，层序Sq2相当于南屯组二段。每个层序发育完整，分别由低水位体系域、水进体系域和高水位体系域组成。针对研究区目的层段所划分层序发育的特点，在层序地层单元划分和对比基础上，对层序格架内的沉积相类型和沉积体系分布规律进行了研究，确定研究区主要发育扇三角洲、辫状河三角洲、湖底扇、湖泊等沉积体系。Sq1层序在凹陷北部发育辫状河三角洲沉积体系, 而在南部发育扇三角洲沉积体系。Sq2层序缓坡带发育辫状河三角洲沉积体系,陡坡带发育扇三角洲沉积体系，湖盆周围发育沼泽相。综合分析各层序沉积特征及演化规律，指出了呼和湖凹陷南部沉积砂体为较有利的勘探区域。

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

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.