• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Geochemistry, geophysics, geosystems >A Sequence of up to 11 Seismic Discontinuities Down to the Midmantle Beneath Southeast Asia
【24h】

A Sequence of up to 11 Seismic Discontinuities Down to the Midmantle Beneath Southeast Asia

机译：在东南亚下方的中间庭院最多11个地震不连续性的顺序

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The Earth's mantle exhibits a layered structure seismically characterized by sudden velocity changes or strong gradients. Several seismic boundaries have been identified in the mantle, and a large number of theoretical calculations and laboratory experiments have contributed to the debate on their origin. We analyze P-to-S converted phases generated at such interfaces to image the velocity structure within the sublithospheric mantle beneath Indonesia. Our study confirms the existence of various layer boundaries in the upper and lower mantle revealing up to 11 consecutive discontinuities down to ~1,700-km depth. We detect Ps phases from the Lehmann and the X discontinuities originating at ~245 and ~294 km, respectively, followed by the top of a low-velocity layer (LVL-410) at ~368 km. The transition zone discontinuities are imaged at average depths of 408 and 665 km, respectively, which indicates the absence of significant temperature anomalies. In the midmantle we find vague indications for another interface at ~970-km depth. At ~1,220 km a negative phase is observed followed by a sequence of converting structures of unknown origin at ~1,320, ~1,460, and ~1,500 km. We interpret these interfaces as compositional anomalies related to persisting fragments of subducted lithosphere. A further boundary is observed at ~1,700 km. Even though different causes exist to explain the observed seismic discontinuities including mineral phase transitions, partial melt, and chemical changes, most of them require additional mineral components. Thus, our findings provide clear evidence for significant compositional alteration of the mantle beneath Indonesia as a result of recurring subduction.
机译：地球的地幔展示了层状结构，其特征在于突然的速度变化或强梯度。在地幔中已经确定了几种地震界限，并且大量的理论计算和实验室实验促成了对其起源的辩论。我们分析在这种界面处产生的P-to-S转换相位以在印度尼西亚下面的副间散道架内的速度结构图像。我们的研究证实了上层和下地幔中各种层边界的存在，显微显示到12个连续的不连续性下降至约1,700公里深度。我们分别检测来自Lehmann的PS阶段，分别在〜245和〜294公里处的X不连续，然后在〜368公里处的低速层（LVL-410）顶部。过渡区不连续性分别以408和665公里的平均深度成像，这表明没有显着的温度异常。在Midmantle中，我们发现在〜970公里深度的另一界面的模糊迹象。在〜1,220公里处，观察到负相，然后在〜1,320，〜1,460和〜1,500公里处转换原状的一系列转化结构。我们将这些界面解释为与悬垂岩石圈的持续性碎片相关的组成异常。在〜1,700公里处观察到进一步的边界。尽管存在不同的原因来解释观察到的地震不连续性，包括矿物相转变，部分熔体和化学变化，但它们中的大多数需要额外的矿物组分。因此，我们的研究结果提供了明确的证据，以便由于经常性俯冲而导致印度尼西亚下面的地幔的显着组成改变。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号