Crustal model of the Bransfield Rift, West Antarctica, from detailed OBS refraction experiments
Crustal model of the Bransfield Rift, West Antarctica, from detailed OBS refraction experiments
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南极洲西部布兰斯菲尔德裂谷的地壳模型，来自详细的 OBS 折射实验
DOI：
10.1111/j.1365-246x.1997.tb05665.x
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发表时间：
1997
影响因子：
2.8
通讯作者：
H. Shimamura
中科院分区：
文献类型：
--
作者：
M. Grad;H. Shiobara;T. Janik;A. Guterch;H. Shimamura
总结
1990/1991年南极夏季，利用灵敏的海底地震仪在西南极布兰斯菲尔德海峡成功地进行了第一次详细的深地震折射研究。实验的重点是布兰斯菲尔德裂谷轴心之下的深层地壳结构。DSS-20地震剖面正好位于布兰斯菲尔德海槽，这被怀疑是一个年轻的裂谷系统。沿着剖面，以50-70 km的间距部署了5个天基信息系统。沿着310公里的纵剖面发射了51发子弹。本文给出了第一次介绍的结果。通过使用二维射线追踪技术对观测到的旅行时间和振幅进行建模，获得了地壳结构的详细模型。最上面的（沉积的？）覆盖层的速度为2.0-5.5 km s-1，深度可达8 km。在此之下，观测到一个速度为6.4-6.8 km s−1的复合体。在剖面中部14-32公里深度范围内发现了一个Vp= 7.3-7.7 km s-1的高速天体。这些不均匀性可以解释为弧后扩张和大陆地壳拉伸的一个阶段，与欺骗布里奇曼火山线相吻合。沿剖面沿着30-32 km深度观测到莫霍面特有的8.1 km s-1速度。
SUMMARY
The first detailed deep seismic refraction study in the Bransfield Strait, West Antarctica, using sensitive OBSs (ocean bottom seismographs) was carried out successfully during the Antarctic summer of 1990/1991. The experiment focused on the deep crustal structure beneath the axis of the Bransfield Rift. Seismic profile DSS-20 was located exactly in the Bransfield Trough, which is suspected to be a young rift system. Along the profile, five OBSs were deployed at spacings of 50-70 km. 51 shots were fired along the 310 km profile. This paper gives the first presentation of the results. A detailed model of the crustal structure was obtained by modelling the observed traveltimes and amplitudes using a 2-D ray-tracing technique. The uppermost (sedimentary?) cover, with velocities of 2.0-5.5 km s−1, reaches a depth of up to 8 km. Below this, a complex with velocities of 6.4-6.8 km s−1 is observed. The presence of a high-velocity body, with Vp= 7.3-7.7 km s−1, was detected in the 14-32 km depth range in the central part of the profile. These inhomogeneities can be interpreted as a stage of back-arc spreading and stretching of the continental crust, coinciding with the Deception-Bridgeman volcanic line. Velocities of 8.1 km s−1, characteristic of the Moho, are observed along the profile at a depth of 30-32 km.