Sediment structure at the equatorial mid-atlantic ridge constrained by seafloor admittance using data from the PI-LAB experiment
Sediment structure at the equatorial mid-atlantic ridge constrained by seafloor admittance using data from the PI-LAB experiment
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使用 PI-LAB 实验数据，受海底导纳约束的赤道大西洋中脊沉积物结构
DOI：
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发表时间：
2019
影响因子：
1.4
通讯作者：
J. Kendall
中科院分区：
文献类型：
--
作者：
U. Saikia;C. Rychert;N. Harmon;J. Kendall
良好约束的海洋沉积物特征（沉积物厚度和剪切波速度）不仅对于地质时间尺度上的气候研究很重要，而且对于纠正和解释其在用于研究更深结构的地震数据中的存在也很重要。我们使用来自 PI-LAB（岩石圈软流圈边界被动成像）实验的数据，该实验由 39 个宽带海底地震仪组成，部署在赤道大西洋中脊附近的链断裂带，覆盖 0-80 Myr 旧海底。我们计算了 18 个站的微震产生的瑞利波频率在 0.1 到 0.2 Hz 之间的海底压力与垂直位移之间的导纳，这些站的数据质量很好，可以确定沉积物厚度和剪切波速度。我们发现沉积物厚度随着海底年龄的增加而增加的总体趋势，正如预期的那样，沉积物厚度范围为 10-450 m，剪切波速度范围为 0.05-0.34 km/s。我们发现山脊两侧的沉积物厚度几乎均匀变化，这表明两侧经历了类似的沉积过程。我们的结果与基于钻探岩心和活动源实验的全球沉积物模型非常一致，但在年龄超过 25 My 的海底的几个站点上厚度薄达 50 m。在我们同时具有 Ps 和导纳估计值的 15 个站点中发现了厚度和剪切速度的导纳和 Ps 估计值之间 95% 置信区域的重叠。这表明这两种方法都能准确估计沉积物厚度。此外，我们的导纳结果将沉积物特征的横向分辨率扩展到之前 Ps 无法解析的站点。
Well-constrained marine sediment characteristics (sediment thickness and shear wave velocity) are important not only for the study of climate over geologic times scales but also for correcting and accounting for its presence in seismic data used to investigate deeper structures. We use data from the PI-LAB (Passive Imaging of the Lithosphere Asthenosphere Boundary) experiment, which consisted of 39 broadband ocean bottom seismometers deployed at the Equatorial Mid-Atlantic Ridge near the Chain fracture zone covering 0–80 Myr old seafloor. We compute admittance between the pressure to the vertical displacement at the seafloor at frequencies between 0.1 and 0.2 Hz for microseism-generated Rayleigh waves for 18 stations where data quality is good to determine the sediment thickness and shear wave velocity. We find a general trend of increasing sediment thickness with the seafloor ages, as expected with sediment thicknesses that range from 10–450 m and, shear wave velocities that range from 0.05–0.34 km/s. We find sediment thickness varies almost uniformly across both sides of the ridge, and it indicates that both sides experienced a similar sedimentation process. Our results are in good agreement with the global sediment model that is based on drilling cores and active source experiments, but thinner by up to 50 m at several stations on seafloor older than 25 My. Overlap of the 95% confidence regions between admittance and Ps estimates for thickness and shear velocity is found at 15 stations where we have both Ps and admittance estimates. It suggests that both methods yield accurate estimates for sediment thickness. In addition, our admittance result extends the lateral resolution of sediment characteristics to stations that were not previously resolved by Ps.
DOI：
10.1029/2018jb016548
发表时间：
2019-02
期刊：
Journal of Geophysical Research: Solid Earth
影响因子：
--
作者：
A. Doran;G. Laske
通讯作者：
A. Doran;G. Laske
影响因子：
3.5
作者：
Straume, E. O.;Gaina, C.;Hopper, J. R.
通讯作者：
Hopper, J. R.