华南武功山地区韧性剪切带的纳米尺度测量研究

Nano-Scaled Study on the Ductile Shear Zone in Wugongshan,South China

在华南加里东造山带中段区域构造调查和中法合作研究的基础上,对武功山地区从新元古代到中生代的韧性板劈理带、逆冲断层带、挤压片理带和拉伸构造带等多种构造类型的变形带,就其超微观纳米粒子结构和动力薄膜进行了扫描电镜（SEM）测量和新的探讨。上述4类韧性剪切带的表层高应变域ab、ac组构面上均发现纳米粒子,颗粒直径一般为50~90nm,并因研磨滚动而形成磨粒（grindinggrains）。由纳米粒、纳米线和纳米层构成一套纳米微线理、面理和组构系统,与宏观的线理和面理平行一致,还可见到完好的超微S-C面理和优选方位的纳米级应力矿物。韧性剪切的所谓静态摩擦,实际上是纳米界限层以微弱摩擦力推进滑移量（slippage）形成的平滑运动,这种平滑运动是纳米级单体和复体磨粒滚动滑移所致。本文从上述几方面揭示了韧性剪切带中纳米粒子存在的普遍性 纳米结构与显微构造的可比性 韧性剪切滑移机理的特殊性。最后,以区内韧性剪切带在地壳浅构造位异常发育的特点,从一个方面讨论华南加里东构造带在系统动力学行为上的时间滞后性。

Based on the Sino-France cooperated regional tectonics investigation of the middle part of the Caledonian orogenic belt in South China, SEM studies on nano-sized particles and dynamic thin-shell or films in different kind of ductile shear zones from Neoproterozoic to Mesozoic （ductile cleavage zone, thrust fault zone, extrusion schistose zone, tensile structural zone） in Wugongshan were carried out. Nano-sized particles（50-90 nm）, grinded and rolled into grinding grains, were found in the ab and ac fabric planes of the high strain zone on the surface of the four types of ductile shear zones. The nano-sized particles, lines and layers composed a system of nano-sized lineation, foliation and fabrication, which parallels to the visual lineation and foliation. Ultra micro S-C foliation and preferred nano-sized stress mineral were also found. In addition, the so-called ＂ static friction＂ is actually the smooth movement, which is formed by slippage pushed by slight friction of nano-sized particle layers, and caused by the grinding and rolling of the nano-sized particle and composed particle. We discovered that the nano-sized particle layers are widely distributed in ductile shear zone, the nano-sized textures is comparable to the micro-sized textures, and the mechanism of ductile shear movement is special. Then, we discussed the system dynamics on the time delay of the Caledonian orogenic belt in South China, since the ductile shear zones were abnormal developed in the superficial structural position of this area.