Lithospheric deformation in the Canadian Appalachians: evidence from shear wave splitting
Lithospheric deformation in the Canadian Appalachians: evidence from shear wave splitting
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加拿大阿巴拉契亚山脉岩石圈变形：剪切波分裂的证据
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
L. Petrescu
中科院分区：
文献类型：
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作者：
A. Gilligan;I. Bastow;E. M. Watson;F. Darbyshire;V. Levin;W. Menke;V. Lane;David Hawthorn;A. Boyce;M. Liddell;L. Petrescu
板块尺度的变形预计将赋予岩石圈上的地震各向异性组构。
确定了快横波方向（φ）和快横波和慢横波之间的延迟时间。
通过SKS分裂的慢分裂剪切波（δt）可以帮助设置空间和时间约束
关于岩石圈变形加拿大的阿巴拉契亚山脉经历了多次
古生代的增生碰撞
劳伦提斯与冈瓦纳大陆的碰撞以及与中生代开启有关的裂谷作用
在北大西洋。然而，伸展事件在多大程度上
古老的造山运动趋势是不确定的。我们通过测量地震波来解决这个问题。
加拿大阿巴拉契亚山脉下的各向异性，计算剪切波分裂参数
新斯科舍省和新玩法新建和现有地震台站的（φ，δt）。平均δt
值为1.2 s，相对短的长度尺度（≥100 km）分裂参数变化，
缺乏与绝对板块运动方向和地幔流模型相关性，
化石岩石圈各向异性组构主导了我们的结果。最快方向平行
在地表观察到阿巴拉契亚造山趋势，而δt值指向连贯
地壳和地幔岩石圈的变形。中生代裂谷对我们的影响微乎其微
研究区域，除了芬迪湾和新斯科舍省南部的局部地区，
方向与中生代裂谷的张开方向近似平行;
>1 s需要跨越地壳和地幔的各向异性层，这意味着
芬迪湾的地震不仅仅是一次地壳构造事件。
Plate-scale deformation is expected to impart seismic anisotropic fabrics on the lithosphere.
Determination of the fast shear wave orientation (φ) and the delay time between the fast and
slow split shear waves (δt) via SKS splitting can help place spatial and temporal constraints
on lithospheric deformation. The Canadian Appalachians experienced multiple episodes of
deformation during the Phanerozoic: accretionary collisions during the Palaeozoic prior to
the collision between Laurentia and Gondwana, and rifting related to the Mesozoic opening
of the North Atlantic. However, the extent to which extensional events have overprinted
older orogenic trends is uncertain. We address this issue through measurements of seismic
anisotropy beneath the Canadian Appalachians, computing shear wave splitting parameters
(φ, δt) for new and existing seismic stations in Nova Scotia and New Brunswick. Average δt
values of 1.2 s, relatively short length scale (≥100 km) splitting parameter variations, and a
lack of correlation with absolute plate motion direction and mantle flow models, demonstrate
that fossil lithospheric anisotropic fabrics dominate our results. Most fast directions parallel
Appalachian orogenic trends observed at the surface, while δt values point towards coherent
deformation of the crust and mantle lithosphere. Mesozoic rifting had minimal impact on our
study area, except locally within the Bay of Fundy and in southern Nova Scotia, where fast
directions are subparallel to the opening direction of Mesozoic rifting; associated δt values of
>1 s require an anisotropic layer that spans both the crust and mantle, meaning the formation
of the Bay of Fundy was not merely a thin-skinned tectonic event.