亚干变质核杂岩的运动学涡度与剪切作用类型  

KINEMATIC VORTICITY NUMBER AND SHEAR TYPE RELATED TO THE YAGAN METAMORPHIC CORE COMPLEX ON SINO MONGOLIAN BORDER

作　　者：郑亚东[1] 

机构地区：[1]北京大学地质学系,北京100871

出　　处：《地质科学》1999年第3期273-280,共8页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金

摘　　要：运用极摩尔圆法、张量分析法和应力取向分析法对内蒙亚干变质核杂岩的剪切作用类型进行了定量分析。相关韧性剪切带的运动学涡度值为 ０．５３—０．８７， 表明相关的剪切作用为减薄型一般剪切。其间的差异，表明主期以简单剪切为主，递进变形过程中， 纯剪切组分增加， 这很可能与因晚期脆性断层引起的位移分解作用有关。同向伸展褶劈理的取向与剪切带边界的夹角既不等于两流脊间的夹角，也不等于其值之半，但可据以确定主应力方向。Kinematic analyses are made in the shear zone in the Yagan metamorphic core complex using techniques of the polar Mohr construction, the deformation tensor and the orientation of the major principal stress( σ 1). The kinematic vorticity numbers related to the shear zone range from 0.53—0.87. The contemporary kinematic vorticity number is 0.87 and the late one is 0.53. The difference shows the shear zone was thinned and changed from simple shear-dominated to pure shear-dominated shear zone during its progressive deformation and implies a more pure shear component involved in the late shear stage, which probably was related to displacement-field partitioning caused by displacements on the brittle normal faults. The angle between the synthetic ecc and the shear zone is neither the angle between the two flow apophyses nor half of it. The orientation of the major principal stress( σ 1) inferred from the synthetic ecc, however, may be used to calculate the angle between the two flow apophyses and the associated kinematic vorticity number.

关 键 词：极磨尔圆 应力取向 变质核杂岩 运动学涡度 

分 类 号：P588.36[天文地球—岩石学] P588.3[天文地球—地质学]