摘要
郯庐断裂带江苏段在白垩纪伸展活动中发育了四条北北东走向的大型正断层,自东向西分别简称F1、F2、F3和F4断层。它们控制发育了北北东向展布的东地堑、西地堑及两者之间的地垒,东地堑内部还出现了一条北北东向的F5断层。详细的野外地质调查表明,郯庐断裂带江苏段活断层广泛出现,F2、F3与F5活断层以逆冲活动为主,而F1断层北段则为逆右行平移活动。活断层擦痕反演应力场显示这些活断层是在北东东-南西西向挤压作用下活动,与现今的应力状态相似。根据活断层对第四系沉积及地貌的控制规律认为,F1、F2、F3与F5断层的最新活动时代为晚更新世,F4断层北段在第四纪以来发生过活动,F4断层南段在第四纪以来没有活动迹象。通过断距及第四系沉积特征分析认为,江苏段各断层中F2与F5断层的活动强度最大。通过详细野外地质调查及有关资料分析,本文认为F1、F2、F3及F4活断层多为白垩系地堑边界正断层直接复活成因,具有不均一分段活动的特点;而倾向多变的F5活断层则是利用东地堑边界断层的同向或反向正断层复活。关于该断裂带新构造活动规律与机制的正确认识,对理解其第四纪以来的构造演化、地震活动规律及中国东部近代动力学等问题,具有十分重要的意义。
Four NNE-striking major normal faults were developed along the Jiangsu part of the Tan-Lu Fault Zone during Cretaceous extensional activities. They are abbreviated by F1, F2, F3 and F4 faults from east to west. The normal faults controll development of the NNE trending eastern graben, western graben and a horst between the two grabens. The Fs fault occurs in the eastern graben. Detailed field investigation shows that active faults widely appear in the Jiangsu part of the Tan-Lu Fault Zone. The F2, F3 and F5 active faults mainly show thrusting while the northern segment of the F1 fault presented reverse dextral slip. Computation of fault-slip data suggests that activity of the active faults resulted from ENE-WSW compression which is consistent with present stress filed in this region. According to control of activity faults on deposition and topography, it is suggested that the latest active time for the F1 , F2, Fa and F5 faults was late Pleistocene, and that the northern part of the F4 fault is active since Quaternary whereas the southern part exhibits no Quaternary activity. Fault displacement data and Quaternary deposition suggest that the F2 and Fs faults show more strong activity. Detailed field investigation and previous data analysis indicate that the active faults in the Jiangsu part are derived mostly from direct reactivity of previous normal fault, and present the characteristics of inhomogeneous and discontinuous activities. The F5 active fault with a longer extension in the Shandong part extends into the Jiangsu part, and shows the formation mechanism of previous normal fault reactivity. The neotectonic activities and mechanism have important implications for understanding the Quaternary structural evolution, earthquake activities and geodynamics in eastern China.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2015年第8期1352-1366,共15页
Acta Geologica Sinica
基金
中国地质调查局项目(编号:1212011120104)
国家自然科学基金项目(编号:41472186)资助的成果
关键词
郯庐断裂带
江苏段
活断层
活动强度
活动时间
Tan-Lu Fault Zone
Jiangsu part
active fault~ active intensity~ active time According tocontrols of activtiy fault on depositonal framework and topography
