地质通报2013，Vol.32Issue(2)：408-423,16.
辽西医巫闾山地区韧性剪切带的应变与运动学涡度
Strain and kinematic vorticity analysis of the ductile shear zone in Yiwulüshan area, western Liaoning Province
摘要
Abstract
The Yiwulushan metamorphic core complex was formed by two stages of extension that occurred in Middle-Late Jurassic and Early Cretaceous respectively. Finite strain measurement shows that the Flinn exponent of the earlier extension (Middle-Late Jurassic) and the later extension(Early Cretaceous) are 0.50～6.06 (2.78 on average) and 0.21～2.39 (1.23 on average) respectively. The kinematic vorticity 3. estimated by Polar Mohr Circle diagram of earlier extension is 0.00-0.82 (0.56 on average), whereas the later extension's Wk is 0.5-0.93 (0.75 on average). The Wk of the extensional crenulation cleavage (C') estimated by C' method ranges from 0.31 to 0.72. The analysis of finite strain and kinematic vorticity suggests that the two stages of extension in Yiwulushan area were asymmetrical, and the strain type of Middle-Late Jurassic deformation is pure dominated general shearing with elongation at earlier extension and plane strain at later extension. Plane strain with equally simple and pure shearing at earlier extension and pure dominated at later extension constitute the strain type of Early Cretaceous deformation. A comparison of the deformation conditions and paleo-stresses of two stages of extension indicates that the earlier extension is characterized by higher deformation temperature, lower differential stress and higher strain rate, whereas the later extension is characterized by lower temperature, higher differential stress and lower strain rate. All these characteristics, combined with the modes of occurrence and deformation features of syn-extensional dikes, plutons and their wall rocks, suggest that decompressed melting occurred in the middle and lower crust under an approximately horizontal extension in Yiwulushan area in Middle-Late Jurassic period; after a short compression at the end of Late Jurassic, the area underwent an approximately horizontal extension in early Early Cretaceous and then the deformation turned into perpendicular uplift, and finally led to the formation of metamorphic core complex.关键词
医巫闾山/伸展变形/应变分析/运动学涡度/变质核杂岩Key words
Yiwuliishan/ extensional deformation/ strain analysis/ kinematic vorticity/ metamorphic core complex分类
天文与地球科学引用本文复制引用
李刚,刘正宏,李永飞,刘俊来,徐仲元,李世超..辽西医巫闾山地区韧性剪切带的应变与运动学涡度[J].地质通报,2013,32(2):408-423,16.基金项目
中国地质调查局项目《古亚洲洋构造体制与滨太平洋构造体制叠加转变的综合调查和研究》(编号:1212011085473)、《兴蒙造山带基本构造格局综合调查和研究》(编号:1212011085476)和国家自然科学基金《内蒙古大青山高级变质岩部分熔融与流变机制研究》(批准号:40972135)与吉林大学研究生创新基金《辽西医巫闻山变质核杂岩形成与岩浆活动》(编号:20121067) （编号:1212011085473）
