辽东凸起北段新生代隆升时间的确定:来自裂变径迹的证据

对取自辽东凸起北段凸起带和陡坡带的6个岩芯样品进行了磷灰石裂变径迹(AFT)测试并分析了裂变径迹特征,选定其中2个样品在约束条件下进行热史模拟。结果表明,辽东凸起北段新生代经历了距今50 Ma±孔店组沉积期末及距今24 Ma±的东营组沉积期末的2次构造隆升。通过对辽东湾坳陷东西部的沉积结构和控凹断裂对比可知,辽东湾坳陷一系列NE向隆起具有相似的发育机制。结合渤海湾盆地区域构造背景,推断辽东湾坳陷辽东凸起的形成是古近纪地幔热活动引起的伸展作用在孔店组沉积期末的构造响应,形式为拆离性质的翘倾断块;而辽东凸起的第二次抬升是受东营组沉积期末发生的区域性构造抬升运动影响的结果。

Determination of uplifting ages during Cenozoic in northern Liaodong Uplift:evidence from fission track dating

The apatite fission track test of six core samples collected from uplift zone and steep slope zone of the northern Liaodong Uplift is performed． The characteristics of fission track and two typical samples' thermal his- torical simulation under the constraint conditions indicate that the northern Liaodong Uplift has two uplifting stages including the end of Kongdian stage (50 Ma ± ) and the end of Dongying stage (24 Ma ± ) in the Cenozoic． The comparison about the sedimentary structures and the main faults controlling the evolution of sags between the eastern and the western depressions reveals that the developmental mechanism of a series of NE trending uplifts in Liaodong Bay Depression is tremendously similar for each other． Combined with the regional tectonic background of the Bohai Bay Basin，the formation of the Liaodong Uplifts in Liaodong Bay Depression can be considered as a tectonic re- sponse at the end of Kongdian stage in the form of tilted fault blocks with the property of detachment in Liaodong Bay because of the extensional regime caused by the Paleogene geo- thermal activity in mantle． And the second up- lifting of the Liaodong Uplift is actually triggered by regional tectonic uplifting movement of the Bohai Bay Basin at the end of the Dongying stage．