Slice of intraoceanic arc: Insights from the first multichannel seismic reflection profile across the South Sandwich island arc
Slice of intraoceanic arc: Insights from the first multichannel seismic reflection profile across the South Sandwich island arc
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洋内弧切片：南桑威奇岛弧第一个多道地震反射剖面的见解
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
D. Smythe
中科院分区：
文献类型：
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作者：
L. Vanneste;R. Larter;D. Smythe
我们提出了第一个多道地震（MCS）反射线，穿越南桑威奇海沟，南桑威奇岛弧，东斯科舍海弧后盆地。这条线与地震目录数据相结合，用于解释夹层板上的应变分布以及弧前结构与海沟处运行过程的关系。MCS数据揭示了一个1.2公里高的断层陡坎与20公里宽的弧形倾斜块在中前弧，这些功能表明大规模的重力塌陷，地震数据是一致的，在该地区的浅深度的沟槽正常的扩展。然而，几乎没有证据表明三明治板块内部存在分布延伸。MCS数据显示，在距离海沟仅18公里的地方有一个小的锋面楔，其厚度最大。弧后磁力数据、弧前中期伸展和锋面楔的小尺寸都与长期和持续的俯冲侵蚀相一致。地震数据表明，这种侵蚀发生在板间应力较低的环境中。
We present the first multichannel seismic (MCS) reflection line that crosses the South Sandwich Trench, South Sandwich island arc, and East Scotia Sea backarc basin. The line is used in combination with earthquake catalogue data to interpret the strain distribution across the Sandwich plate and the relationship of forearc structures to processes operating at the trench. The MCS data reveal a 1.2-km-high fault scarp associated with a 20-km-wide arcward-tilted block in the mid-forearc; these features indicate large-scale gravitational collapse, and earthquake data are consistent with trench-normal extension at shallow depth in this area. There is, however, little evidence of distributed extension within the interior of the Sandwich plate. The MCS data show a small frontal wedge that achieves its maximum thickness only 18 km from the trench. Backarc magnetic data, mid-forearc extension, and the small size of the frontal wedge are all consistent with long-term and ongoing subduction erosion. Earthquake data suggest that this erosion is taking place in an environment of low interplate stress.