Electronic Resource
Azimuthal Seismic Anisotropy of 70‐Ma Pacific‐Plate Upper Mantle
| العنوان: | Azimuthal Seismic Anisotropy of 70‐Ma Pacific‐Plate Upper Mantle |
|---|---|
| المؤلفون: | Mark, H. F., Lizarralde, D., Collins, J. A., Miller, N. C., Hirth, G., Gaherty, J. B., Evans, R. L. |
| المصدر: | Wiley |
| بيانات النشر: | American Geophysical Union (AGU) 2022-02-15T20:08:19Z 2022-02-15T20:08:19Z 2019-01-28 |
| نوع الوثيقة: | Electronic Resource |
| مستخلص: | Plate formation and evolution processes are predicted to generate upper mantle seismic anisotropy and negative vertical velocity gradients in oceanic lithosphere. However, predictions for upper mantle seismic velocity structure do not fully agree with the results of seismic experiments. The strength of anisotropy observed in the upper mantle varies widely. Further, many refraction studies observe a fast direction of anisotropy rotated several degrees with respect to the paleospreading direction, suggesting that upper mantle anisotropy records processes other than 2-D corner flow and plate-driven shear near mid-ocean ridges. We measure 6.0 ± 0.3% anisotropy at the Moho in 70-Ma lithosphere in the central Pacific with a fast direction parallel to paleospreading, consistent with mineral alignment by 2-D mantle flow near a mid-ocean ridge. We also find an increase in the strength of anisotropy with depth, with vertical velocity gradients estimated at 0.02 km/s/km in the fast direction and 0 km/s/km in the slow direction. The increase in anisotropy with depth can be explained by mechanisms for producing anisotropy other than intrinsic effects from mineral fabric, such as aligned cracks or other structures. This measurement of seismic anisotropy and gradients reflects the effects of both plate formation and evolution processes on seismic velocity structure in mature oceanic lithosphere, and can serve as a reference for future studies to investigate the processes involved in lithospheric formation and evolution. |
| مصطلحات الفهرس: | Article, http://purl.org/eprint/type/JournalArticle |
| URL: | Journal of Geophysical Research: Solid Earth |
| الاتاحة: | Open access content. Open access content Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. |
| ملاحظة: | application/pdf English |
| Other Numbers: | MYG oai:dspace.mit.edu:1721.1/140387 2169-9313 2169-9356 Mark, H. F., Lizarralde, D., Collins, J. A., Miller, N. C., Hirth, G., Gaherty, J. B., & Evans, R. L. (2019). Azimuthal seismic anisotropy of 70-Ma Pacific-plate upper mantle. Journal of Geophysical Research: Solid Earth, 124, 1889– 1909. 1342474323 |
| المصدر المساهم: | MASSACHUSETTS INST OF TECHNOL LIBRS From OAIster®, provided by the OCLC Cooperative. |
| رقم الانضمام: | edsoai.on1342474323 |
| قاعدة البيانات: | OAIster |
| الوصف غير متاح. |