今天是2018年01月17日

辽吉裂谷带北缘连山关韧性剪切带的构造属性和运动学分析

DOI:10.3799/dqkx.2017.140

作者:常瑞虹,李伟民,刘永江,梁琛岳,李婧,张丽,刘昕悦,范文亮

联系地址:吉林大学地球科学学院,吉林长春 130061

摘要:韧性剪切带在岩石圈地壳中广泛存在,蕴含应力、应变和温压等环境参数,是构造解析、流变学和成因机制研究的重要对象.辽吉裂谷带位于辽宁东部-吉林南部,是华北克拉通重要的古元古代活动带之一.连山关岩体地处辽吉裂谷带北缘,经历复杂变质变形作用,岩体南缘发育NWW向右行走滑韧性剪切带.糜棱岩显微结构观测分析揭示,剪切带内糜棱岩以S、SL构造岩为主,总体呈压扁型应变.运动学涡度值为0.91~0.97,均大于0.75,指示简单剪切为主的变形特征.糜棱岩中云母显示塑性拉长,石英动态重结晶明显,以膨凸重结晶作用为主.EBSD分析结果表明,石英发育中低温菱面组构,对应变形温度450~550℃,暗示糜棱岩形成于低绿片岩相-低角闪岩相.结合前人研究成果,我们认为连山关韧性剪切带可能起源于早元古代晚期.连山关岩体先后经历早期隆起造成的伸展-滑脱作用和晚期与上覆辽河群共同经历的南北向挤压,从而在岩体南缘形成陡倾的右行韧性剪切带.

关键字:连山关岩体;韧性剪切带;有限应变分析组构分析;运动学;辽吉裂谷带;构造.

Structural Properties and Kinematic Analysis of Lianshanguan Ductile Shear Zone in Northern Liao-Ji Rift Zone,Northeastern North China Craton

Author:Chang Ruihong, Li Weimin, Liu Yongjiang, Liang Chenyue, Li Jing, Zhang Li, Liu Xinyue, Fan Wenliang

Author Address:College of Earth Sciences, Jilin University, Changchun 130061, China

Abstract:The ductile shear zone is widely discovered in the lithospheric crust, and it contains abundance environmental parameters such as stress, strain temperature and pressure, hence it is an important object for the study of structural analysis, rheology and genetic mechanism. The Liao-Ji rift zone is one of the ancient primitive activities of the North China craton, located in the east of Liaoning Province and North of Jilin Province. The Lianshanguan granitic body, exposed in the Northern margin of Liao-Ji rift zone, experienced complex metamorphic deformation. The mylonitic in the ductile shear zone have obvious dextral strike-slip characteristics with an NWW strike. The observation and analysis of the microstructure of mylonitic reveals that the taconite developed in shear zone is S-SL type, representing a flattening strain. Kinematics vorticity of 0.91-0.97, which are greater than 0.75, indicates that the shearing is formed in the general shear dominated simple shear. In addition, The quartz dynamic recrystallization is obvious, while the mica shows plastic elongation. The quartz c-axis EBSD analysis shows that the quartz fabric is characterized by the middle to low temperature rhomb slip system, corresponding deformation temperature of 450-550℃, consistent with a greenschist-low amphibolite facies condition. Based on the previous studies, the forming age of the ductile shear deformation is considered to be the late Early Proterozoic. In conclusion, the Lianshanguan granitic body suffered an initial uplift stage, resulting extension-stretching-decollement within the Liaohe Formation surrounding the granitic body. Subsequently, the studied area was suffered a S-N directing compression, and led to the dextral strike-slip ductile shearing.

Keyword:Lianshanguan granitic body; ductile shear zone; finite strain analysis; fabric analysis; kinematic; Liao-Ji rift zone; tectonics.

 

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作者简介:常瑞虹(1992-),女,硕士,构造地质学.ORCID:0000-0002-1326-3622.E-mail: 1901386894@qq.com

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