内蒙古塔木素地区NNE向韧性剪切带发现及变形时代分析

Discovery of the NNE Ductile Shear Zone and its Deformation Age Analysis of Tamusu Area,Inner Mongolia

塔木素地区NNE向韧性剪切带位于塔里木板块东缘与华北板块西北缘板块碰撞拼接边界,呈NNE向展布,长约9 km,宽150～2 500 m。褶皱的糜棱面理、拉伸线理、旋转残斑、书斜构造、"云母鱼"等构造均指示其为右行逆冲走滑剪切。形成温度为300℃～500℃,围压为250～400 MPa,变形变质作用相当于绿片岩相,差应力(σ)为93.7～116.5 MPa。应变速率(ε)为10-17 s-1(300℃)和10-13 s-1(500℃)。主体变形时间在(256.0±1.3)Ma之后,三叠纪之前,为华力西(海西)运动末期产物。

NNE-trending ductile shear zone of Ta mu su is located at the boundary between on the eastern side of Talimu and on the west-north side of north China blocks collision- amalgamation zone.It extents in a nearly NNE direction with a length of 9 km and a width of 150~2500 m.Structural Styles,including folded mylonitic foliation,mineral lineation, rotational porphyroclast,＂domino＂structure and ＂mica fish＂,indicate a dextral thrusting strike-slip. This ductile shear zone might occur at a metamorphic grade of green-schist facies, temperature at 300-500~C and pressure at 250-400MPa, The Values of differential structural stresses（~） are estimated at 93.7~116.5 MPa,Strain rate（e） is 10＂17 sl（300~C） and 10-13 s^（500^C）.The main ductile shear zone deformation time formed between（256.0：~l.3） Ma and the Triassic by comprehensive evaluation,was formed by the late Variscan （Hercynian） movement.