Kinematic analysis of the Taiwan Slate Belt
Kinematic analysis of the Taiwan Slate Belt
复制标题
台湾板岩带的运动分析
DOI：
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发表时间：
1995
期刊：
影响因子：
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通讯作者：
T. Byrne
中科院分区：
文献类型：
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作者：
Kennen S. Tillman;T. Byrne
根据台湾板岩带的褶皱和解理几何形状以及有限和增量应变历史，可以将其划分为两个构造域。这两个带大致对应了台湾的两个地形范围：雪山山脉和主干山脉。雪山山脉岩石具有直立对称褶皱和陡东南倾轴向平面压溶解理的特征。压力阴影中的同动纤维通常呈直线状，平行于解理，并向下倾斜，表明岩石经历了同轴应变历史。主干带的岩石发育向前陆倾斜的不对称褶皱，呈中等东南倾、轴向平面压力解理。同动纤维是直的，平行于XY剖面的下倾拉伸线理。然而，在XZ截面中，纤维通常显示顺时针曲率（从NE方向看），表明非同轴应变历史。我们认为，不同的应变历史至少部分是由于两个地区地层原始构造地层环境的差异。雪山山脉的地层被解释为沉积在与东倾正断层有关的半地堑中。相比之下，主干山脉的地层被认为是沉积在无断层的中国大陆边缘。研究认为，半地堑东侧的基底基底起着陡面刚性挡块作用，集中了整个雪山山脉大部分地区的纯剪切变形；剪切应变明显地局限于沉积层序底部附近和背挡附近的区域。主干山脉的非同轴应变特征被解释为区域尺度剪切带的结果，该剪切带形成于中国基底，其沉积盖层在吕宋弧下方东南逆冲。
The Taiwan Slate Belt can be subdivided into two structural domains based on fold and cleavage geometries and finite and incremental strain histories. The two belts correspond generally to two topographic ranges in Taiwan: the Hsuehshan Range and the Backbone Range. Rocks in the Hsuehshan Range are characterized by upright, symmetric folds and a steeply SE dipping, axial planar pressure solution cleavage. Synkinematic fibers in pressure shadows are typically straight, parallel to cleavage, and plunge downdip, indicating that the rocks experienced a coaxial strain history. In contrast, rocks in the Backbone Range are characterized by inclined, asymmetric folds that verge toward the foreland and display a moderately SE dipping, axial planar pressure solution cleavage. Synkinematic fibers are straight and parallel to the downdip stretching lineation in XY sections. In XZ sections, however, the fibers typically display a clockwise curvature (viewed to the NE), indicating a noncoaxial strain history. We propose that the different strain histories are due, at least in part, to differences in the original tectonostratigraphic settings of the strata in the two ranges. Strata in the Hsuehshan Range are interpreted to have been deposited in a half-graben associated with an east dipping normal fault. The strata of the Backbone Range, in contrast, are considered to have been deposited on the unfaulted Chinese continental margin. We suggest that the basement horst on the east side of the half-graben functioned as a steep-faced, rigid backstop that concentrated pure shear deformation throughout most of the Hsuehshan Range; shear strains were apparently limited to zones near the base of the sedimentary sequence and adjacent to the backstop. The noncoaxial strains characteristic of the Backbone Range are interpreted to be the result of a regional-scale shear zone that formed as Chinese basement and its sedimentary cover were underthrust southeastward beneath the Luzon Arc.