海拉尔盆地呼和湖凹陷白垩系层序地层特征及沉积演化

以层序地层学理论为指导，通过对全凹陷范围内的地震、钻井、测井、岩心以及古生物等资料的综合研究，建立了呼和湖凹陷白垩系层序地层格架。将呼和湖凹陷白垩系划分为3个一级层序(TSq1-TSq3)、5个二级层序(Ⅰ-Ⅴ)、8个三级层序(Sq1-Sq8)；并在层序格架内进行沉积相划分和沉积体系研究，确定该区主要发育冲积扇、扇三角洲、辫状河三角洲、湖底扇和湖泊沉积等沉积体系。其中冲积扇沉积体系主要分布在早期Sq1层序中；扇三角洲沉积体系主要分布在Sq2层序的南部和Sq5层序的北部；而辫状河三角洲沉积体系在Sq3、Sq4层序中尤其发育，并在Sq2层序的北部也有所发育；湖底扇沉积体系主要发育在Sq2、Sq3和Sq4层序的洼陷带；湖泊沉积体系主要发育在各层序的洼陷带。沉积体系在平面与纵向上的演化受古构造与古地貌的控制，呼和湖凹陷南部沉积砂体为较有利的勘探区域。

Sequence Stratigraphic Character and Sedimentary Evolution in Cretaceous in Huhehu Depression in Hailaer Basin

Based on the theory of sequence stratigraphy, sequence stratigraphy framework in Cretaceous in Huhehu depression was established by comprehensively research of seismic data, cores and well logging data. Cretaceous in Huhehu depression was divided into 3 first-order sequences(TSq1-TSq3), 5 second order sequences(Ⅰ-Ⅴ) and 8 third-order sequences(Sq1-Sq8). Sedimentary facies were classified, and sedimentary system was studied in sequence framework. Study area mainly developed alluvial fan, fan delta, braided delta, subaqueous fan, lacustrine sediment and so on. Alluvial fan sedimentary system mainly distributed in Sq1 sequence；Fan delta sedimentary system mainly distributed in the south of Sq2 sequence and the north of Sq5 sequence; Braided delta sedimentary system mainly distributed in Sq3 sequence and Sq4 sequence, and it was developed in the north of Sq2 sequence; subaqueous fan sedimentary system mainly distributed in the depression belt of Sq2 and Sq4 sequence; The lateral and vertical evolution of sedimentary system was controlled by palaeostructure and palaeogeomorphology, and sedimentary sand bodies in the south of Huhehu depression were the favorable exploring area.