松辽盆地北部姚家组底界面特征及其动力学背景

以松辽盆地北部地震资料精细构造解释和钻井资料分析为基础，对其姚家组底界面特征展开了详细的研究。结果表明：在该界面之下的地层内发育了4组近NNE走向长距离延伸的微幅褶皱带，并且这4组褶皱带的隆起幅度由东向西逐渐减小；沿该界面发育了东薄西厚的红色古土壤层；古生物资料也显示界面上下有明显的物种组合突变现象。地球物理、沉积、古生物等证据揭示，姚家组底界面是发育在盆地裂后热沉降期内的一个具有挤压背景的区域性角度不整合面。磁性地层、古生物和同位素年龄均显示该界面的发育时代为晚白垩纪(距今约88.5Ma)，与中生代期间欧亚板块与太平洋板块间一次重大的板块构造运动学重组事件一致。由此推断，松辽盆地北部姚家组底界面是晚白垩纪板块构造重组事件在松辽盆地内的响应界面，至此开始，松辽盆地进入了构造反转演化阶段。

Characteristics and dynamic background of bottom boundary in Yaojia Formation of the northern Songliao Basin

On the basis of the interpretation and analysis of the seismic and drilling data of the northern Songliao Basin, the characteristics of the bottom boundary of Yaojia Formation (T11 boundary) were described and studied. Four groups of large-scale broad low-relief NNE fold belts below the T11 boundary were distinguished. The uplift amplitude caused by the four groups of fold-thrust belts decreased from east to west. The thickness of red palaeosoil beds developed in the T11 boundary also slowly gets thiner from east to west. The palaeontologic data suggested that there were several age-specific biomarkers on the upper and low surfaces of this boundary. The data of geophysics, sedimentology and palaeontology indicated that the T11 boundary was a regional angular unconformity formed in a compression regime during the post-rift thermal subsidence phase of Songliao Basin. The data from stratigraphy, palaeontology and isotopic dating ages revealed that the T11 boundary was formed during the period of the late Cretaceous (about 88.5Ma before present). This age is consistent with the time of a great reorganization between Pacific plate and Eurasian plate in the Mesozoic time. Therefore, the T11 boundary in the northern Songliao Basin was the responding surface to interaction between the Pacific plate and Eurasian plate in the Late Mesozoic. Since then, Songliao Basin had gotten into tectonic inversion evolution phase.