2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 59-12
Presentation Time: 4:00 PM

CRUSTAL AND UPPER MANTLE STRUCTURES OF THE RED SEA AND ARABIAN SHIELD REGIONS


ABSTRACT WITHDRAWN

, amsamri@ksu.edu.sa

The Arabian Peninsula is an area characterized by poor seismic activities. While the Arabian Shield and Arabian Platform are aseismic, the area is ringed with regional seismic sources in the tectonically active areas of Iran and Turkey to the northeast, the Red Sea Rift bordering the Shield to the southwest, and the Dead Sea Transform fault zone to the north. Red Sea is considered one of only a few places in the world undergoing active continental rifting and formation of new oceanic lithosphere. We determined the seismic velocity structure of the crust and upper mantle of the Arabian Shield and Red Sea using a variety of analysis techniques on broadband seismic waveform data recorded by KACST and SGS seismographic Networks.

Teleseismic P- and S-wave travel time tomography provided an image of upper mantle compressional and shear velocities related to thermal variations. Regional Pn tomography delineated compressional velocity structure of the shallow mantle. Modeling of Teleseismic P-wave receiver functions estimated crustal and upper mantle discontinuity structure. Finally, Measurements of teleseismic shear-wave splitting estimated upper mantle anisotropy.

Generally speaking, new results for the lithosphere suggest that the mantle lithosphere is thin and the LVZ is significant near the Red Sea, where rifting is active. The mantle lid thickens away from the Red Sea in the Arabian interior. Furthermore our results indicate the presence of polarization anisotropy in the lithospheric upper mantle, in the vicinity, as well as farther away from the Red Sea. Our modeling suggests vSV > vSH in the southern part of the Red Sea, consistent with vertical flow, and vSH > vSVin the northern part of the Red Sea and the continental interior, as is commonly reported in the continents. We would suggest that low velocity beneath the Gulf of Aqabah and southern Arabian Shield and Red Sea at depths below 200 km are related to mantle upwelling and seafloor spreading. Low velocities beneath the northern Arabian Shield below 200 km may be related to volcanism. The low velocity feature near the eastern edge of the Arabian Shield and western edge of the Arabian Platform could be related to mantle flow effects near the interface of lithosphere of different thickness.