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Investigating the velocity structure beneath the Southern and Central Atlantic; Implications for evolution of oceanic crust and lithosphere

机译：研究南大西洋和中大西洋下方的速度结构；对大洋地壳和岩石圈演化的影响

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Presented here is the shear velocity structure of the crust and upper mantle beneath\udthe central and southern Atlantic Ocean from inversion of high resolution group velocity\udtomography. The path average group velocities from Rayleigh waves were picked\udusing multi filter technique and phase match filtering for 14,000 paths. They were then\udcombined within a tomographic inversion, to obtain the regional variations of velocity\udstructure at a range of short to intermediate periods (14 s - 100 s). These group velocities\udhave depth sensitivities from the surface to approximately 90 km depth, constraining\udthe focus to velocity variations within the crust and mantle lithosphere. Tomographic\udresults highlight short wavelength variations at periods sensitive to shallow\uddepths, implying the possibility for a more complex velocity structure than currently\udexpected for the oceanic region. The results show a clear relationship between increasing\udgroup velocities and increasing sea floor age. Group models are then inverted to\udobtain the shear velocity structure with respect to depth. The shear velocity model\udhighlights slow velocities beneath the ridge, interpreted as the upwelling of asthenosphere\udbetween depths between 30 km and 50 km. Models of crustal and lithospheric\udthickness are extrapolated from the data. These models suggest the evolution of the\udAtlantic Ocean is more complex than the simple mathematical cooling models. It is\udsuggested that the main control on crustal thickness is tectonic processes associated\udwith the slow spreading rate and not controlled by to the mantle potential temperature.\udAdditionally, results are presented which incorporate 2 azimuthal anisotropy in\udthe tomographic inversions. At the longest periods test show that the recovered anisotropy\udis an artefact of the inversion process, and cannot be interpreted in terms of\udmantle flow. At the shortest periods there is a possible relationship between the fast\uddirection and the stress field.
机译：这里展示的是高分辨率群速度\渗流层析成像反演中大西洋南部和南部以下地壳和上地幔的剪切速度结构。使用多重滤波技术和相位匹配滤波对来自瑞利波的路径平均群速度进行了\ 14,000条路径的拾取。然后将它们\在断层图像反演中进行组合，以获取在短期到中期（14 s-100 s）范围内速度\ udstructure的区域变化。这些群速度\具有从地表到大约90 km深度的深度敏感性，从而限制了\ u003cWed \ u003b \ u003b \ u003b \ u003b \ u003b聚焦于地壳和地幔岩石圈内的速度变化。断层摄影\结果表明，在对浅\ uddepth敏感的时期，波长变化很短，这意味着速度结构可能比目前对海洋地区的预期更为复杂。结果表明，增加\ udgroup速度与增加海床年龄之间存在明显的关系。然后将组模型进行倒置，以\\获得关于深度的剪切速度结构。剪切速度模型\突出显示了山脊下方的缓慢速度，这被解释为软流圈的上升运动\在介于30 km和50 km之间的深度之间。从数据推断出地壳和岩石圈\厚度模型。这些模型表明，大西洋的发展比简单的数学冷却模型更为复杂。有人认为，对地壳厚度的主要控制是与缓慢扩散有关的构造过程，而不是受地幔势温度控制。\此外，提出了在层析成像反演中纳入2个方位各向异性的结果。在最长的时期内，测试表明，所恢复的各向异性\\是反演过程的假象，并且不能用\\ mantleman流动来解释。在最短的时间内，快速\方向和应力场之间可能存在关系。

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    McCarthy, Emily Suzanne;

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  • 年度 2015
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  • 正文语种 {"code":"en","name":"English","id":9}
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