Abstract The Canadian High Arctic preserves a long and complex tectonic history, including craton formation, multiple periods of orogenesis, extension and basin formation, and the development of a passive continental margin. We investigate the possible preservation of deformational structures throughout the High Arctic subcontinental lithosphere using measurements of seismic anisotropy from shear wave splitting at 11 seismograph stations across the region, including a N-S transect along Ellesmere Island. The majority of measurements indicate a fast-polarisation orientation that parallels tectonic trends and boundaries, suggesting that lithospheric deformation is the dominant source of seismic anisotropy in the High Arctic; however, a sub-lithospheric contribution cannot be ruled out. Beneath Resolute in the central Canadian Arctic, distinct back-azimuthal variations in splitting parameters can be explained by two anisotropic layers. The upper layer is oriented E–W and correlates with tectonic trends and the inferred lithospheric deformation history of the region. The lower layer has a ∼NNE–SSW orientation and may arise from present-day convective mantle flow beneath locally-thinned continental lithosphere. In addition to inferences of anisotropic structure beneath the Canadian High Arctic, measurements from the far north of our study region suggest the presence of an anisotropic zone in the lowermost mantle beneath northwest Alaska.

中文翻译：

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加拿大北极地区的地震各向异性：来自横波分裂的证据

摘要 加拿大高北极地区保留了漫长而复杂的构造历史，包括克拉通形成、多期造山、伸展和盆地形成以及被动大陆边缘的发育。我们使用该地区 11 个地震台站的剪切波分裂的地震各向异性测量值来调查整个北极次大陆岩石圈变形结构的可能保存，包括沿埃尔斯米尔岛的 NS 横断面。大多数测量结果表明与构造趋势和边界平行的快速极化方向，表明岩石圈变形是高北极地区地震各向异性的主要来源；然而，不能排除次岩石圈的贡献。在加拿大北极中部的 Resolute 之下，分裂参数的不同后方位变化可以用两个各向异性层来解释。上层为东西向，与该地区的构造趋势和推断的岩石圈变形历史相关。下层具有~NNE-SSW 方向，可能来自局部变薄的大陆岩石圈下方的现今对流地幔流。除了对加拿大北极地区下方各向异性结构的推论外，来自我们研究区域最北端的测量结果表明，阿拉斯加西北部最下地幔中存在各向异性带。下层具有~NNE-SSW 方向，可能来自局部变薄的大陆岩石圈下方的现今对流地幔流。除了对加拿大北极地区下方各向异性结构的推论外，来自我们研究区域最北端的测量结果表明，阿拉斯加西北部最下地幔中存在各向异性带。下层具有~NNE-SSW 方向，可能来自局部变薄的大陆岩石圈下方的现今对流地幔流。除了对加拿大北极地区下方各向异性结构的推论外，来自我们研究区域最北端的测量结果表明，阿拉斯加西北部最下地幔中存在各向异性带。