郯庐断裂带南段晚期韧性剪切带涡度分析及其构造意义  

Vorticity Analysis of the Late Ductile Shear Zone in the Southern Segment of the Tancheng—Lujiang Fault Zone and Its Tectonic Significances

作　　者：王勇生[1] 朱光[1] 宋传中[1] 刘国生[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,230009

出　　处：《地质论评》2006年第5期591-600,共10页Geological Review

基　　金：国家自然科学基金资助项目(编号40272094)的成果。

摘　　要：天然剪切带通常都是简单剪切和纯剪切叠加的一般剪切的产物。通过测量韧性剪切带的运动学涡度，可以很好地解决剪切带变形过程中究竟是简单剪切占优势还是纯剪切占优势的问题。本次研究中利用石英C轴组构与主应变比值的方法以及石英C轴组构与斜列颗粒形态的方法，测量了郯庐断裂带南段晚期韧性剪切带的运动学涡度。获得的运动学涡度主要介于0．80～0．95之间，明显大于0．75且小于1，指示郯庐晚期左旋走滑韧性剪切带的变形以简单剪切为主的同时，还存在一个纯剪切分量。根据本次研究获得的涡度值、断层产状以及断裂带的运动学特征综合分析，可以认为郯庐晚期韧性剪切带是一个具有压扭性质的走滑构造。并且，本次工作中获得的运动学涡度支持伊佐奈崎板块与欧亚板块的边界为典型的汇聚型板块边界的现有成果。Fault zone is produced by general shear activities comprising simple shear and pure shear. Vorticity analysis can solve the problems that whether simple shear or pure shear takes an advantage in deformation of a shear zone. This paper used two approaches such as quartz C-axis fabrics and strain ratios, oblique grain shapes and quartz C-axis fabrics to measure kinematic vorticity numbers of the late ductile shear zone in southern segment of the Tancheng--Lujiang （Tan-Lu） fault zone. The kinematic vorticity numbers are between 0.80 and 0. 95 and bigger than 0. 75 and smaller than 1. 0, which suggests that the deformation within the Tancheng- Lujiang later ductile shear zone is not a strict simple shear but includes a component of pure shear. According to the kinematic vorticity numbers, kinematic nature and attitude of the Tancheng--Lujiang fault zone, it is concluded that the Tancheng-Lujiang later ductile shear zone is a strike-slip structure with transpression. It agrees with that the boundary between Izanagi plate and Eurasia plate is convergent plate boundary from the kinematic vorticity numbers.

关 键 词：郯庐断裂带 晚期韧性剪切带 运动学涡度 压扭 

分 类 号：P542.3[天文地球—构造地质学]