Strain Partitioning between structural domains in the forearc of the Hikurangi Subduction Zone, New Zealand
Strain Partitioning between structural domains in the forearc of the Hikurangi Subduction Zone, New Zealand
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新西兰希库朗吉俯冲带弧前结构域之间的应变划分
DOI：
10.1029/91tc02363
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发表时间：
1992
期刊：
影响因子：
4.2
通讯作者：
K. Berryman
中科院分区：
文献类型：
--
作者：
S. Cashman;H. Kelsey;C. Erdman;H. Cutten;K. Berryman
太平洋板块沿着新西兰北岛东海岸的希库朗伊边缘在南纬39°50′处与澳大利亚板块倾斜汇聚。霍克斯湾地区北岛东海岸有一个广泛且年轻的暴露于地下的前弧，为记录这一倾斜会聚边缘环境中的同期前弧变形提供了机会。中尺度和巨尺度应变的地质绘图和分析表明，应变分为伸展、收缩和走滑区域。这些域是细长的并且趋势平行于边缘。前弧净缩短和横流滑移的测量表明，倾斜会聚运动通过板块界面传递。计算过去 1-2 m.y 的变形率所有六个弧前区域的结构占太平洋-澳大利亚板块汇聚所需的边缘平行运动的 50-70%，约占垂直于板块边界的板块运动的 6%。在弧前表面，这种倾斜会聚运动不是由压扭断层表现出来的，而是由成对的构造域表现出来的，这些构造域由走滑断层带和沟槽一侧伴随的收缩断层和褶皱带组成。有两个这样的横断层和收缩对，一个是在弧前的弧形边缘处逆止器日光，另一个对是相对未受干扰的前弧盆地的沟渠。弧前陆上部分相对于走滑的少量缩短表明，垂直于板块边界的缩短可能集中在近海，并且垂直于板块边界的板块运动的大部分分量可能是通过沿俯冲带巨型逆冲的滑动来调节的。
The Pacific plate obliquely converges with the Australian plate at latitude 39°50′S along the Hikurangi margin off the east coast of the North Island of New Zealand. An extensive and youthful subaerially exposed forearc on the east coast of the North Island in the Hawke's Bay area provides the opportunity to document contemporaneous forearc deformation in this obliquely convergent margin setting. Geologic mapping and analysis of strain at both mesoscale and megascale indicates that strain is partitioning into domains of extension, contraction, and strike-slip. The domains are elongate and trend parallel to the margin. Measurements of net shortening and transcurrent slip in the forearc show that the obliquely convergent motion is transferred across the plate interface. Deformation rates calculated for the past 1–2 m.y. for structures in all six forearc domains account for 50–70% of the margin-parallel motion required by Pacific-Australian plate convergence and about 6% of the plate motion perpendicular to the plate boundary. At the surface in the forearc, this obliquely convergent motion is manifest not by transpressional faults but rather by paired structural domains that consist of a strike-slip fault zone and an accompanying contractional fault-and-fold zone on the trenchward side. There are two such transcurrent faulting-and-contraction couplets, one where the backstop daylights at the arcward edge of the forearc and another couplet trenchward of a relatively undisturbed forearc basin. The small amount of shortening, relative to strike-slip, in the onshore part of the forearc suggests that shortening perpendicular to the plate boundary may be concentrated offshore and that most of the component of plate motion perpendicular to the plate boundary may be accommodated by slip along the subduction zone megathrust.