孙吴-嘉荫盆地中新生代构造特征及演化

Structural features and evolution of the Sunwu-Jiayin basin from Mesozoic to Cenozoic

针对东北亚中新生代盆地构造演化具有复杂性和特殊性,依据对各种地质资料的综合解释与分析,剖析了孙吴-嘉荫盆地中新生代断裂特征,建立了一条横穿整个盆地的地震-地质区域大剖面,由此分析了盆地演化史.结果表明:孙吴-嘉荫盆地在宁远村组沉积时期,全盆地属于受北北东向伸展断裂控制的断陷盆地.淘淇河组沉积早期,盆地出现东西部的分异,东部表现为早期控陷断裂反转逆冲活动,此后进入了拗陷发育阶段,而此时西部仍为持续的断陷阶段;至淘淇河组沉积晚期,西部开始抬升剥蚀,东部为持续拗陷阶段.晚白垩世时盆地整体进入断陷后热沉降阶段;晚白垩世末盆地再次遭受挤压,形成典型的"下正上逆"正反转构造.新生代盆地进入挤压改造期,形成一系列以北西西向为主的具有压扭性质的右行走滑断裂.

Aimed at studying the complexity of tectonic evolution of the Mesozoic-Cenozoic ba- sins in Northeast Asia in particular. Base on comprehensive interpretation and analyses of the geological and geophysical data, and constructed regional geological section across the basin, the Mesozoic and Cenozoic fault systems of the Sunwu-Jiayin basin were studied and the evolu- tion of the basin discussed. The results show that the whole Sunwu-Jiayin basin is a faulted ba- sin controlled by early Cretaceous NNE extensional faults that occurred during the deposition period of the Ningyuancun formation. The Jiayin region, which is located in the eastern part of the study area, was uplifted and suffered erosion during the early stage of the deposition period of the Taoqihe formation, while the Sunwu region in the western part remained to be a faulted basin. The Jiayin region evolved as a depression, whereas the Sunwu region was uplift and subjected to erosion during the late stage of the deposition period of the Taoqihe formation. Then the whole basin entered the depression phase due to the thermal subsidence after rifting,and received a wide deposition during the late Cretaceous. The basin suffered compression a- gain at the end of the late Cretaceous, causing reactivation and reversion of the early faults. Since the Cenozoic, the compression stress has all along been existing in the study area, and a set of NWW-trending right-lateral transpressional strike-slip faults were thereby formed.