南图尔盖盆地几种典型地震相分析及其地质意义

Several Typical Seismic Facies in South Turgay Basin and the Geological Meaning

以地震地层学、层序地层学的理论为指导,依据地震反射参数,充分利用地震反射的内部结构、外部形态,结合振幅、频率、连续性等特点,对南图尔盖盆地下侏罗统-下白垩统10个地震层序进行地震相识别,划分出中振幅-中连续前积反射、中振幅-中连续上超反射等6种典型地震相。这些地震相在平面上具有明显差异性,纵向上具有一定继承性与阶段性,继承性表现在盆地西部物源、东部物源在各个不同时期相对稳定,持续发育,其空间分布变化不大;阶段性则表现在不同层序可分为三个组合:SQ1-SQ4时期(阶段Ⅰ)地震相类型差异大,相带变化快;SQ5-SQ8时期(阶段Ⅱ)地震相沿地堑长轴方向,呈条带状展布;SQ9-SQ10时期(阶段Ⅲ)盆地内地震相均匀分布,各地堑统一连通。

Under the guidance of seismic stratigraphy and sequence stratigraphy, according to the seismic reflection parameters, such as seismic reflection of the internal structure and external form combining with the characteristics of amplitude, frequency, continuity and so on, the seismic facies in South Turgai Basin from lower Jurassic to lower Crataceous were identified and dirided, identify nine species seismic facies, they includes foreset facies with medium amplitude and moderate continuity, onlap-filling facies with medium amplitude and moderate continui- ty, disorderly reflection with medium amplitude and moderate continuity, parallel sheet facies with strong amplitude and moderate continuity, divergent filling reflection with strong amplitude and moderate continuity, clutter reflection with medium amplitude and poor continuity. These seismic facies are obviously different on the plane and have inheritance and stage on the longitudinal, inheritance is shown on the basin provenance in different period is relatively stable, sustained development and the spatial distribution of little change; period is shown on the divided three different combinations：SQ1--SQ4 period （stage I ） ： large difference of seismic facies types and seismic facies change fast. SQ5--SQ8 period （stage II ） ： the seismic facies is along the long axis and show a zonal distribution. SQ9--SQlO period （stage III） ：the seismic facies is evenly distributed and they are continuous distribution in different grabens.