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首页> 外文期刊>Journal of geodynamics >Deformation from the convergence of oceanic lithosphere into Yap trench and its implications for early-stage subduction
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Deformation from the convergence of oceanic lithosphere into Yap trench and its implications for early-stage subduction

机译：海洋岩石圈汇聚到雅浦海沟的变形及其对早期俯冲的影响

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摘要

The surface expression generated by convergence of two oceanic plates and sinking of the older lithosphere into the mantle is one of the most spectacular features of our planet, and yet very little is understood about the onset of this dynamic process. This is largely due to the lack of modern-day analogues where causal relationships among various subduction parameters can be investigated. Here we report a rare example in the western Pacific where variations in style of deformation and state of stress are observed on a young trench-arc system as a result of subduction of the Oligocene Caroline plate beneath the Philippine Sea plate along the Yap Trench. The unique features of this system include a short trench-arc distance (～50 km), narrow trench (<50 km), and the presence of the Caroline Ridge, a region of massive volcanic outflow formed on the subducting Caroline plate, which is divided into two by the Sorol Trough trending WNW-ESE. While the timing of collision is uncertain and the possible rejuvenation of an old subduction zone can not be ruled out, the convergence apparently changed to subduction when the Caroline plate reached the mechanically weak part of the overriding plate. The style of deformation changes at approximately 9°N, which corresponds to the southern border of the Sorol Trough. To the north, the area is generally characterized by extensional features on the arc and slab with a large half graben (100 km x 50 km) on the plate entering the subduction zone. To the south, compression is the dominant mode of deformation on the arc and slab. The average depth of the subducting plate to the north lies 500 m higher than to the south, and this height appears to be maintained by broad flexural bending applied by the Yap and southern Mariana Trenches. Although the convergence rate is higher to the north of Sorol Trough than the south, the gravity anomalies show that the slab has advanced deeper into the asthenosphere to the south, which is interpreted as evidence that subduction started later to the north than south. The study also reveals that during the initial early stage of subduction a broad flexure may develop on the slab, but with further convergence, the deformation is localized and the slab is deflected at the maximum bending point.
机译：由两个大洋板块汇聚以及较旧的岩石圈沉入地幔而产生的表面表情是我们星球最引人注目的特征之一，但对于这种动态过程的开始知之甚少。这主要是由于缺乏现代的类似物，在这种情况下可以研究各种俯冲参数之间的因果关系。在这里，我们报告了一个西太平洋地区的罕见例子，由于沿雅浦海沟沿菲律宾海板下方的渐新世卡罗琳板块俯冲，在年轻的海沟弧系统上观察到了变形样式和应力状态的变化。该系统的独特之处包括：短的弧形弧距离（〜50 km），窄的弧形沟槽（<50 km）以及加罗琳岭（Caroline Ridge）的存在，加罗琳俯冲板块上形成了大规模的火山喷流。由Sorol槽趋势WNW-ESE分为两部分。虽然碰撞的时机不确定，不能排除旧俯冲带可能恢复新生的可能性，但当卡罗琳板到达上覆板的机械薄弱部分时，收敛显然变成了俯冲。变形样式在大约9°N处变化，这对应于Sorol槽的南部边界。在北部，该区域的特征通常是弧形和平板的延伸特征，进入俯冲带的板块上有一个大的半抓斗（100 km x 50 km）。在南方，压缩是弧形和平板变形的主要方式。俯冲板块向北的平均深度比向南的平均深度高500 m，并且该高度似乎由邑和南马里亚纳海沟施加的大范围弯曲弯曲得以维持。尽管Sorol槽北部的收敛速度比南部高，但重力异常表明板块已向南延伸到软流圈的更深处，这被解释为俯冲开始于北部比南部晚的证据。研究还表明，在俯冲初期，平板可能会出现较大的挠曲，但是随着进一步的收敛，变形会局部化，平板会在最大弯曲点发生挠曲。

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  • 来源
    《Journal of geodynamics》 |2004年第1期|p.83-102|共20页
  • 作者

    Sang-Mook Lee;

  • 作者单位

    Marine Resources Laboratory, Korea Ocean Research and Development Institute, Ansan, PO Box 29, Seoul 425-600, South Korea;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 天文学、地球科学;
  • 关键词

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