کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4678168 1634839 2010 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Depth dependent azimuthal anisotropy in the western US upper mantle
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
پیش نمایش صفحه اول مقاله
Depth dependent azimuthal anisotropy in the western US upper mantle
چکیده انگلیسی

We present the results of a joint inversion of long period seismic waveforms and SKS splitting measurements for 3D lateral variations of anisotropy in the upper mantle beneath the western US, incorporating recent datasets generated by the USArray deployment as well as other permanent and temporary stations in the region. We find that shallow azimuthal anisotropy closely reflects plate motion generated shear in the asthenosphere in the shallow upper mantle (70–150 km depth), whereas at depths greater than 150 km, it is dominated by northward and upward flow associated with the extension of the East Pacific Rise under the continent, constrained to the east by the western edge of the North American craton, and to the north, by the presence of the East–West trending subduction zone. In particular, the depth-integrated effects of this anisotropy explain the apparent circular pattern of SKS splitting measurements observed in Nevada without the need to invoke any local anomalous structures.

Research Highlights
► Our results reveal 3D azimuthal anisotropy patterns in the western US upper mantle.
► At shallow depths (<150 km) North-American plate motion generated shear dominates.
► At >150 km, flow associated with East Pacific rise interacts with cratonic keel and subduction zone.
► Depth dependent anisotropy explains the SKS splitting circular pattern in the WUS.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 300, Issues 3–4, 1 December 2010, Pages 385–394
نویسندگان
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