Geodetic strain and the deformational history of the North Island of New Zealand during the late Cainozoic
Geodetic strain and the deformational history of the North Island of New Zealand during the late Cainozoic
复制标题
新西兰北岛晚新生代大地应变与变形历史
DOI：
10.1098/rsta.1987.0009
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
R. Walcott
中科院分区：
文献类型：
--
作者：
R. Walcott
新西兰北岛东海岸下的俯冲带从东到西包括锋楔、弧前盆地、形成弧的隆起基底和中央火山区。根据海底扩张数据重建新生代板块边界区需要弧前盆地在过去 20 Ma 内旋转 60°，这已被古地磁偏角研究证实。根据大地测量数据对剪切应变的估计表明，弧前盆地今天正在旋转，并且它在垂直于板块边界区域趋势的方向上延伸。延伸显然是通过正常断层实现的。对俯冲带沉积物数量的估计超过了前楔的体积：过量沉积物造成的底侵被认为是弧前盆地晚第四纪隆起的原因。因此，东海岸深处可能发生低温高压变质作用，而中部火山区可能发生高温低压变质作用。因此，新西兰北岛很可能是正在形成的成对变质带的所在地。
The subduction zone under the east coast of the North Island of New Zealand comprises, from east to west, a frontal wedge, a fore-arc basin, uplifted basement forming the arc and the Central Volcanic Region. Reconstructions of the plate boundary zone for the Cainozoic from seafloor spreading data require the fore-arc basin to have rotated through 60° in the last 20 Ma which is confirmed by palaeomagnetic declination studies. Estimates of shear strain from geodetic data show that the fore-arc basin is rotating today and that it is under extension in the direction normal to the trend of the plate boundary zone. The extension is apparently achieved by normal faulting. Estimates of the amount of sediments accreted to the subduction zone exceed the volume of the frontal wedge: underplating by the excess sediments is suggested to be the cause of late Quaternary uplift of the fore-arc basin. Low-temperature—high-pressure metamorphism may therefore be occurring at depth on the east coast and high-temperature—low-pressure metamorphism is probable in the Central Volcanic Region. The North Island of New Zealand is therefore a likely setting for a paired metamorphic belt in the making.