Crustal anisotropy beneath Pacific Ocean‐Islands from harmonic decomposition of receiver functions
Crustal anisotropy beneath Pacific Ocean‐Islands from harmonic decomposition of receiver functions
复制标题
接收函数调和分解的太平洋岛屿下方地壳各向异性
DOI：
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Jeffrey Park
中科院分区：
文献类型：
--
作者：
T. Olugboji;Jeffrey Park
海洋岛屿下地壳各向异性可归因于优先排列的矿物、裂缝或脉结构。与谐波加权叠加，来自永久海洋岛屿站的接收函数显示了地壳和下镀层中强烈而明显的各向异性参数的证据。我们分析了太平洋上11个IRIS - GSN站的数据。我们观察到双叶接收函数（RF）振幅随后方位角变化的普遍性，与“缓慢”倾斜轴各向异性一致。在大多数情况下，各向异性被安置在下镀地壳中。某代表性台站的综合模拟表明，Vp=10%、Vs=5%的各向异性强度是可能的。推断出的对称轴走向趋向于与板块运动一致，但有一些分散。在西北太平洋的KWAJ、TARA和WAKE台站，对称轴的走向与火山侵位时的板块运动方向一致。在POHA台站和离今天夏威夷热点最近的台站下面，对称轴的排列几乎与板块运动正交。我们将地壳各向异性归因于岩脉结构的优先排列，这些岩脉结构将软流圈岩浆输送到海底火山大厦。我们的研究结果表明，海洋岛屿的热柱起源必须由构造应力非均质性补充，使岩浆能够通过裂缝穿透岩石圈。岩浆输送裂缝应该垂直于最小压缩方向，这是理论模型预测的，在就位时大致与板块运动对齐。
Crustal anisotropy beneath ocean islands can be attributed to preferentially aligned minerals, cracks, or dike structures. Stacked with harmonic weighting, receiver functions from permanent ocean‐island stations display evidence of strong and distinct anisotropy parameters in the underlying crust and underplated layer. We analyze data for 11 IRIS‐GSN stations in the Pacific Ocean. We observe the prevalence of two‐lobed receiver function (RF) amplitude variations with back‐azimuth, consistent with “slow” tilted‐axis anisotropy. In most cases the anisotropy is accommodated in the underplated crust. Synthetic modeling of a representative station indicates that the strength of anisotropy of Vp=10% and Vs=5% is possible. The strike direction of the inferred symmetry axis tends to align with plate motion, with some scatter. At stations in the northwest Pacific i.e., KWAJ, TARA, and WAKE, the strike direction of the symmetry axis aligns with plate motion at the time of volcano emplacement. Beneath station POHA and the closest stations to the present‐day Hawaiian hotspot, alignment of the symmetry axis is almost orthogonal to the plate motion. We attribute the crustal anisotropy to the preferred alignment of dike structures that transported asthenospheric magma toward the seafloor volcanic edifice. Our results suggest that the thermal‐plume origin for ocean islands must be supplemented by tectonic‐stress heterogeneities that allow magma to penetrate the lithosphere via fractures. Magma‐transport fractures should align normal to the least‐compressive direction, which are predicted by theoretical models to align approximately with plate motion at the time of emplacement.
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影响因子：
3.7
作者：
M. Richards;E. Contreras‐Reyes;C. Lithgow‐Bertelloni;M. Ghiorso;L. Stixrude
通讯作者：
M. Richards;E. Contreras‐Reyes;C. Lithgow‐Bertelloni;M. Ghiorso;L. Stixrude
影响因子：
5.2
作者：
B. Heit;F. Sodoudi;X. Yuan;M. Bianchi;R. Kind
通讯作者：
B. Heit;F. Sodoudi;X. Yuan;M. Bianchi;R. Kind
加拉帕戈斯群岛下方岩石圈结构和融化开始的接收函数成像
影响因子：
5.3
作者：
Rychert C
通讯作者：
Rychert C
影响因子：
5.3
作者：
Contreras-Reyes, E.;Grevemeyer, I.;Peirce, C.
通讯作者：
Peirce, C.