佳-伊断裂带韧性变形特征

佳木斯-伊通 ( 佳-伊) 断裂带是郯-庐断裂带北段的西支，控制着佳-伊地堑内各盆地的展布。笔者在佳-伊断裂带中部舒兰水曲柳地区发现一条近 NNE 向的韧性剪切带。结合显微构造分析认为，该剪切带主要由初糜棱岩-糜棱岩组成，具有左行走滑的特征。对研究区内韧性剪切带中的糜棱岩进行有限应变测量 ( Fry 法) ，认为该剪切带应变类型为伸展应变，岩石类型表现为 L/LS 型构造岩; 对糜棱岩样品进行石英 C 轴 EBSD 分析，同样指示佳-伊断裂带中段具有左行走滑的构造特征，石英组构以中低温菱面为主，滑移系为 {101} ＜110 ＞ 。结合前人研究资料，推测佳-伊断裂带中段左行走滑时间为早白垩世中、晚期，形成机制与西太平洋伊泽纳崎板块由 NWW 转变为 NNW 向欧亚大陆的高速俯冲有关。

Characteristics of ductile deformation of Jiamusi-Yitong fault

The Jiamusi-Yitong falut was the western branch of northern extension of Tan-Lu fault, which con- trolled the distributions of many basins within Jia-Yi graben. The authous found a ductile-brittle shear zone with trend of NNE in Shuiquliu of Shulan area. Combining the microstructure study, the authors consider that the shear zone was consisted of protomylonite-mylonite and displayed sinistral strike-slip shear characteristics. With the meas- urement of finite-strain determination （ Fry measurement）, the strain type of the study area was considered to be ex- tension strain. EBSD （ electron back scatter diffraction） measurement also indicated the study area had undergone a sinistral strike-slip shear zone and quartz fabrics were mainly low-middle temperature prism-glide fabrics with slip system of 100011 〈 110 〉. To sum up, Shuiquliu shear zone had experienced a sinistral strike-slip shearing in middle-late Early Cretaceous, which was related to moving direction changing from NWW to NNW of the western Pacific Izanagi plate obliquely subducting under the Eurasia plate.