渤海的地质演化与断裂活动

本文将渤海的地质演化分为:前中生代、中生代和新生代三大时期,并论述各个时期的构造特征和地层分布。渤海的断裂系统主要有北北东—北东、近东西和北西向三组,每组断裂既有其各自的发生、发展规率,同时彼此之间又有一定的关联。

GEOLOGIC EVOLUTION AND FAULTING OF THE BOHAI SEA

Geologic evolution of the Bohai Sea has experienced three stages: Pre-Mesozoic, Mesozoic and Cenozoic. The Pre-Mesozoic basement can be divided into five tectonic units: Shanhaiguan-Yingkou Uplift, Yanshan Depression, West Shandong Uplift, East Shandong Uplift and Fuzhou Depression. Each unit consists of different complex of the Archeozoic, Proterozoic and PaleozoiO rocks. Structural lines are mainly in E-W direction. In the Mesozoic, the Bohai Sea area was in compression stress field and the structural framework is characteristic of NNE-NE faults and folds with volcanic, pyroclastic and sedimentary rocks formed. In the Cenozoic, the Bohai Sea area became an .oil-gas basin. Various superimposed sedimentary formations and tectonic phases occurred in this basin. The last transgression happened in the Early Holocene. And since then Bohai Sea has become a semi-closed gulf. Fault activities dominate in the Bohai tectonic movement, mainly in NNE-NE, near E-W and NW directions. The near E-W faults came the earliest, and the NNE-NE the latest but the best developed.