• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of geodynamics >Crustal structure of the southeastern Iceland-Faeroe Ridge (IFR) from wide aperture seismic data
【24h】

Crustal structure of the southeastern Iceland-Faeroe Ridge (IFR) from wide aperture seismic data

机译：从大口径地震数据看冰岛东南部-法罗岭（IFR）的地壳结构

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 aseismic Iceland-Faeroe-Ridge (IFR) is of central importance in reconstructing the opening of the North Atlantic Ocean. To investigate the crustal structure of the IFR at its southeastern part we conducted a wide aperture seismic survey across the IFR from the Iceland Basin to the Norway Basin. Seismic energy was generated by two 60-litre sleeve guns and recorded by 42 ocean-bottom seismometers (OBS). Kinematic and dynamic forward modeling by two-point ray tracing was applied to develop a 2D velocity-depth model. The accuracy of the model obtained is better than 5% for both velocity and depth of interfaces. We find a Mono depth of 23 km below the crest of the ridge that decreases to about 15 km at either end of the line. The upper part of the crust exhibits P-wave velocities between 5.7 and 6.3 km/s that increase towards the Norway Basin. The lower crust is more homogeneous with v_p ranging from 6.6 to 7.0 km/s. Upper and lower parts of the crust are separated by a first order discontinuity. Amplitudes (P_mP) and arrival times (P_n) of wide-angle phases indicate upper-mantle velocities of 7.9 km/s. Furthermore we analyzed PS-converted phases for upper crustal depth levels and find a v_p/v_s ratio of 1.73 +-0.04 equal to a Poisson's ratio of 0.25 with no significant lateral variations along the seismic line. On the crest of the ridge we identified a basalt layer embedded within the sedimentary sequence that was also penetrated by deep sea drilling and dated to 43 +- 3.3 million years. Below the basalt layer we observed a low-velocity layer that is identified as Mesozoic sediment that was also observed to either end of the basalt. We conclude that the southeastern part of the IFR is composed of stretched continental crust and thus part of Paleo-Europe rather than oceanic crust formed by the Iceland hot spot. This conclusion is supported by the distribution of magnetic anomalies that allow identifying the passive continental margin approximately 100 km to the NW of our seismic line.
机译：抗震的冰岛－法罗河脊（IFR）在重建北大西洋的开放中至关重要。为了调查IFR东南部的地壳结构，我们对从冰岛盆地到挪威盆地的整个IFR进行了大孔径地震勘探。地震能量是由两把60升套筒炮产生的，并由42个海底地震仪（OBS）记录。通过两点射线追踪进行运动学和动态正向建模，以开发二维速度-深度模型。对于界面的速度和深度，所获得模型的精度均优于5％。我们发现，在山脊峰顶下方23 km的Mono深度在该线的两端减小到大约15 km。地壳上部的波速在5.7至6.3 km / s之间，向挪威海盆增加。下地壳更均匀，v_p范围为6.6至7.0 km / s。地壳的上部和下部由一阶不连续点隔开。广角相位的振幅（P_mP）和到达时间（P_n）表示上地幔速度为7.9 km / s。此外，我们分析了PS转换相的上地壳深度水平，发现v_p / v_s比为1.73 + -0.04，等于泊松比为0.25，沿地震线没有明显的横向变化。在山脊的顶部，我们发现了一个沉积在沉积层序中的玄武岩层，该层也被深海钻探所穿透，其年代可追溯到43±330万年。在玄武岩层下方，我们观察到一个低速层，该层被认为是中生代沉积物，在玄武岩的任一端也都观察到了。我们得出的结论是，IFR的东南部分是由伸展的大陆壳组成，因此是古欧洲的一部分，而不是由冰岛热点形成的洋壳。磁异常的分布支持了这一结论，磁异常可以识别距我们地震线西北约100 km的被动大陆边缘。

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