Seismic Anisotropic Layering in the Yilgarn and Superior Cratonic Lithosphere
Seismic Anisotropic Layering in the Yilgarn and Superior Cratonic Lithosphere
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DOI：
10.1029/2020jb021575
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发表时间：
2021-08
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通讯作者：
Xiaoran Chen;V. Levin;Huaiyu Yuan;M. Klaser;Yiran Li
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作者：
Xiaoran Chen;V. Levin;Huaiyu Yuan;M. Klaser;Yiran Li
克拉通岩石圈内的分层已经使用一系列技术在不同的克拉通中进行了探索和报告。然而，所有克拉通的岩石圈是否存在共同特征尚不清楚。在这项研究中，我们对西澳大利亚的伊尔加恩克拉通和北美的苏必利尔克拉通进行了比较研究，这两个克拉通在整个构造历史中从未直接接触过。为了详细描述两个克拉通的岩石圈层状，我们采用调和分解的接收函数分析来表征每个克拉通 4 个长期运行地点下方的各向异性地震结构。我们可以在两个克拉通的所有地点识别出 170 公里以上的多个独特的各向异性边界。克拉通内部和克拉通之间的各向异性边界的性质是不同的。我们的观察结果与普遍接受的克拉通岩石圈至少由两层组成的观点一致。此外，它为之前的视图添加了新的细节，并揭示了数百公里距离内各向异性特性的横向变化。各向异性的这种变化可能反映了克拉通最终组装之前的构造历史，并表明水平运动对于克拉通岩石圈的形成是必要的。
Layering within the cratonic lithosphere has been explored and reported in different cratons using a range of techniques. However, whether there exists a common feature in the lithosphere for all the cratons is not clear yet. In this study, we carry out a comparison study between the Yilgarn craton in Western Australia and the Superior craton in North America that have never been in direct contact throughout their tectonic history. To have a detailed description of the lithospheric layering in both cratons, we employ receiver function analysis with harmonic decomposition to characterize the anisotropic seismic structure beneath 4 long‐operating sites in each craton. We can identify multiple unique anisotropic boundaries above 170 km at all sites in both cratons. Properties of the anisotropic boundaries are distinct both within and across the cratons. Our observation agrees with a commonly accepted view of the cratonic lithosphere consisting of at least two layers. Moreover, it adds new details to the previous view and reveals lateral variations of the anisotropic properties over distances of a few hundreds of kilometers. Such variations in anisotropic properties likely reflect the tectonic history predating the final assembly of cratons, and suggest horizontal movements are necessary for the formation of cratonic lithosphere.