塔木察格盆地塔南凹陷下白垩统层序结构特征及控制因素分析

Analysis of Sequence Structure and Its Controlling Factors in Lower Cretaceous in Tanan Depression,Tamuchage Basin

应用层序地层学原理对塔南凹陷下白垩统地层进行了划分和对比,建立了等时的层序地层格架,分析了不同级别层序界面的特征。对层序结构特征的研究表明,不同沉积期的层序类型、沉积体系的空间展布和配置关系有明显区别。SQ1层序为初始裂谷期湖泊层序,发育冲积扇、滨浅湖等沉积组合;SQ2层序为裂谷高峰早期湖泊层序,发育冲积扇、扇三角洲、滨浅湖等沉积组合;SQ3层序为裂谷高峰中晚期湖泊层序,发育扇三角洲、湖底扇、浅湖、深湖等沉积组合;SQ4层序为裂谷后期过渡层序,发育半深湖—深湖,大型长轴三角洲、滨浅湖等沉积组合。不同层序发育期各层序的结构特征决定着特定沉积相带的展布,沉积体系域的沉积相构成也有变化。

Based on the principle of sequence stratigraphic methodologies, the sequence in Lower Cretaceous in Tanan depression is classified and correlated in detail, the strata framework of sequence is defined and established, and the characteristic of sequence boundary of different grade is analyzed. The study of the structure of the sequence and sedimentary system shows the type of sequence and the spatial distributions and sedimentary system vary significantly in different depositional stage. SQ1 is formed in initial rift lacustrine basins, in which the sedimentary systems as alluvial fan, Shore-shallow lacustrine is developed. SQ2 is formed in early maximum rift lacustrine basins, in which the sedimentary system as fan delta, suhlacustrine fan and Shore-shallow lacustrine is developed. SQ3 is formed in middle and later maximum rift lacustrine basin, in which the sedimentary system as fan delta, sub-lacustrine fan and deep-shallow lacustrine is developed, SQ4 is formed in post rift lacustrine basin, in which the sedimentary system as longitudinal delta, shore-shallow lacustrine, shallow lacustrine and semi-deep lake is developed. In different sedimental stage, the distribution of different sequence control the special distribution of sedimentary facies, and the variation of architecture of sedimentary facies of system tracts.