郯庐断裂带中段电性结构及其地学意义研究

摘要

Tancheng-Lujiang fault zone is an important strike-slip fault system in eastern China continent,and has significant status to study the forming,evolution and current structure of China continent. The magnetotelluric(MT) sounding profile from Alashanzuoqi to Rizhao city Shandong province crossed the middle part of Tancheng-Lujiang fault zone at Juxian of Shandong province,where its strike angle is about NE20 degrees as shown by strike analysis. The resistivity model of 2D MT inversion shows that the width of Tancheng-Lujiang fault zone is about 30 km at where the profile crossed it,the main part of Tancheng-Lujiang fault zone consists of two deep and steep faults,the western one dips to west steeply with a dip angle about 70 degrees obliquity and its penetration depth is about 60 km; the eastern one dips to east with a dip angle 60～80 degrees and its penetration depth is 80～100 km. Both of these two faults incised the crust,but limited in lithosphere. The crust is resistive from the eastern edge of Tancheng-Lujiang fault zone to Rizhao city,which is very different to the west of the fault zone,this fact indicates that Tancheng-Lujiang fault zone is the boundary between North China block and Jiao-Liao-Korea block.%郯庐断裂带是中国大陆东部一个重要的左行走滑断裂系,对于研究中国大陆的形成演化与构造格局有着十分重要的意义.阿拉善左旗一山东日照超宽频带大地电磁测深剖面在山东莒县附近穿越了郯庐断裂带中段,电性主轴分析结果表明断裂带附近构造走向大致为北东20°;反演电阻率模型表明剖面穿越处郯庐断裂带的宽度约为30 km.断裂带主体是两条切割深度大、陡倾的断裂,西侧断裂切割深度约为60 km,向西倾斜,断面陡立,倾角约为70°,东侧断裂切割深度大于80 km,但小于100 km,界面东倾,陡立,倾角约为60°～80°;这两条断裂都切穿了地壳,但未切穿岩石圈.郯庐断裂带东缘至削面终端日照,整个地壳为高阻,与断裂带西侧地壳的电性结构差异明显,这表明郯庐断裂带是华北地块与胶辽朝地块的边界断裂.