کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6429206 1634755 2014 15 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Origin of azimuthal seismic anisotropy in oceanic plates and mantle
ترجمه فارسی عنوان
منشاء بی نظمی لرزه ای آزیموتال در صفحات اقیانوسی و گوشته
کلمات کلیدی
بی نظمی لرزه ای، گرمازدگی شبکه ترجیحا جهت گیری، لیتوسفر اقیانوسی، آستنوسفر، لایه های مرزی ترمو شیمیایی،
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات علوم زمین و سیاره ای (عمومی)
چکیده انگلیسی


- Mantle flow models match newly imaged azimuthal anisotropy in the upper mantle.
- Age dependence of oceanic plate misfits explained by half-space cooling.
- Mechanical lithosphere overlies simple asthenospheric shearing layer.

Seismic anisotropy is ubiquitous in the Earth's mantle but strongest in its thermo-mechanical boundary layers. Azimuthal anisotropy in the oceanic lithosphere and asthenosphere can be imaged by surface waves and should be particularly straightforward to relate to well-understood plate kinematics and large-scale mantle flow. However, previous studies have come to mixed conclusions as to the depth extent of the applicability of paleo-spreading and mantle flow models of anisotropy, and no simple, globally valid, relationships exist. Here, we show that lattice preferred orientation (LPO) inferred from mantle flow computations produces a plausible global background model for asthenospheric anisotropy underneath oceanic lithosphere. The same is not true for absolute plate motion (APM) models. A ∼200km thick layer where the flow model LPO matches observations from tomography lies just below the ∼1200°C isotherm of a half-space cooling model, indicating strong temperature-dependence of the processes that control the development of azimuthal anisotropy. We infer that the depth extent of shear, and hence the thickness of a relatively strong oceanic lithosphere, can be mapped this way. These findings for the background model, and ocean-basin specific deviations from the half-space cooling pattern, are found in all of the three recent and independent tomographic models considered. Further exploration of deviations from the background model may be useful for general studies of oceanic plate formation and dynamics as well as regional-scale tectonic analyses.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Earth and Planetary Science Letters - Volume 401, 1 September 2014, Pages 236-250
نویسندگان
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