摘要
详细的野外和室内宏观及微观构造分析和有限应变测量结果表明，自中生代以来，本区至少经历了两期变形，即早期的收缩应变及后期的伸展应变。收缩应变主要表现为滑脱一逆冲推覆作用，具有显著的构造层次性，自中、下构造层次至上构造层次依次表现为：基底与盖层之间以角门石及长石碎斑为主的糜棱岩为特征的韧性滑脱剪切带、盖层中长岭子组内的韧脆性滑脱剪切带及上都盖层中的寒武系、石炭系等过冲于佛罗系之上的逆冲推覆构造；在该构造变形过程中伴随有强烈的岩浆活动，表明当时的区域热流值较高。伸展应变及同时发生的基底隆升作用，主要表现为基底和盖层中的韧性正剪切带及大量的正断层，基底中大量的ＮＮＥ向张性白垩纪花岗斑岩脉及区域性的ＮＮＥ向白垩纪盆地的形成都和本期构造活动相关。辽南地壳基底中大量的沿糜棱面理发育的长英质岩脉表明剪切变形过程中具有局部熔融作用的发生。对长英质岩脉经流体包裹体成分测试表明主要成分为分子水。在野外对长英质脉体的研究表明至少有两期：形成与滑脱作用有关的长英质脉体为含钾长石少、斜长石多、白色；而和伸展应变有关的长英质脉体钾长石含量明显增大，呈红色。两种长英质脉的褶皱变形反映了各自的变形机制。剪切作用过程中发生的动态局部熔融作用，?
Detailed macro and micro-scale structure analyses and finite strain measurements have revealed that there are significant differences in the structure characters in crustal deformation between pre-and post-Mesozoic. Due to the superimposition and reconstruction of later deformation, the pre-Mesozoic structures can only be seen with difficulty in the Archean basement. Since Mesozoic, the area of interest has experienced at least two stages of deformation: the early contraction and late extension. Contraction:Decollement-thrusting caused three levels of structural deformation from lower to up: 1. the ductile shear zone represented by mylonite zone developed between metamorphic basement and sedimentary cover3 2. the ductile and brittle shear zone developed within the Changlingzi Formation being a relatively weak zone in the cover3 and 3. the thrust zone shown by the overthrusting of the Cambrian and Carboniferous strata onto the Jurassic stratum. The middle and lower level structures such as stretching lineation, shear folds, A-type folds,asymmetric rotational porphyroclast and S-C fabric both on macro and micro-scale were resulted from the westward decollment. In addition, regional magmatism accompanied this stage tectonic movement suggested that the regional heat flux was relatively high.Extension: This stage deformation occurred at about 118 -- 103Ma accompanying the uplifting of metamorphic basement. It is mainly characterized by ductile normal shear zones and a great number of brittle normal faults developed both in the basement and in the cover.The formation of NNE trending tensile Cretaceous granitoid veins and regional NNE striking Cretaceous basins such as Pulandian Basin, Beihai Basin and Xiongyue Basin had close relation with this deformation, suggesting that the inner and neighbouring areas of the basement were at the tensional environment owing to the uplifting of basement. The development of a great number of felsic veins parallel to the foliation of mylonite in the basement indicates that dynamic part
出处
《高校地质学报》
CAS
CSCD
1996年第2期155-165,共11页
Geological Journal of China Universities
关键词
韧性剪切带
金州隆起
辽南
流体作用
构造变形
Southern Liaoning, ductile shear zone, dynamic partial melting. uplifting,Jinzhou uplifting region.
