Seismic anisotropy and subduction-induced mantle fabrics beneath the Arabian and Nubian Plates adjacent to the Red Sea

• Published in: Geophysical research letters 2014-04, Vol.41 (7), p.2376-2381
• Main Authors: Elsheikh, Ahmed A., Gao, Stephen S., Liu, Kelly H., Mohamed, Abdelnasser A., Yu, Youqiang, Fat-Helbary, Raafat E.
• Format: Article
• Language: English
• Subjects: Anisotropy; Egypt; Fabrics; Lithosphere; Mantle; mantle flow; Oceanography; Orientation; Plate tectonics; Plates (tectonics); Red Sea; Saudi Arabia; seismic anisotropy; Seismology; shear-wave splitting; Splitting; Stations
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1002/2014GL059536

For most continental areas, the mechanisms leading to mantle fabrics responsible for the observed anisotropy remain ambiguous, partially due to the lack of sufficient spatial coverage of reliable seismological observations. Here we report the first joint analysis of shear‐wave splitting measurements obtained at stations on the Arabian and Nubian Plates adjacent to the Red Sea. More than 1100 pairs of high‐quality splitting parameters show dominantly N‐S fast orientations at all 47 stations and larger‐than‐normal splitting times beneath the Afro‐Arabian Dome (AAD). The uniformly N‐S fast orientations and large splitting times up to 1.5 s are inconsistent with significant contributions from the lithosphere, which is about 50–80 km thick beneath the AAD and even thinner beneath the Red Sea. The results can best be explained by simple shear between the lithosphere and the asthenosphere associated with northward subduction of the African/Arabian Plates over the past 150 Ma. Key Points Uniform N‐S fast orientations on both sides of the Red Sea The results are inconsistent with plume or fossil fabric models Anisotropy may originate from upper asthenosphere due to long‐term subduction