Upper mantle structure under western Saudi Arabia from Rayleigh wave tomography and the origin of Cenozoic uplift and volcanism on the Arabian Shield

Journal Article · Fri Nov 09 04:00:00 EST 2007 · Geochemistry, Geophysics, Geosystems , vol. 9, N/A, July 25, 2008, Q07020

OSTI ID:946929

Park, Y; Nyblade, A; Rodgers, A; Al-Amri, A

The shear velocity structure of the shallow upper mantle beneath the Arabian Shield has been modeled by inverting new Rayleigh wave phase velocity measurements between 45 and 140 s together with previously published Rayleigh wave group velocity measurement between 10 and 45 s. For measuring phase velocities, we applied a modified array method that minimizes the distortion of raypaths by lateral heterogeneity. The new shear velocity model shows a broad low velocity region in the lithospheric mantle across the Shield and a low velocity region at depths {ge} 150 km localized along the Red Sea coast and Makkah-Madinah-Nafud (MMN) volcanic line. The velocity reduction in the upper mantle corresponds to a temperature anomaly of {approx}250-330 K. These finding, in particular the region of continuous low velocities along the Red Sea and MMN volcanic line, do not support interpretations for the origin of the Cenozoic plateau uplift and volcanism on the Shield invoking two separate plumes. When combined with images of the 410 and 660 km discontinuities beneath the southern part of the Arabian Shield, body wave tomographic models, a S-wave polarization analysis, and SKS splitting results, our new model supports an interpretation invoking a thermal upwelling of warm mantle rock originating in the lower mantle under Africa that crosses through the transition zone beneath Ethiopia and moves to the north and northwest under the eastern margin of the Red Sea and the Arabian Shield. In this interpretation, the difference in mean elevation between the Platform and Shield can be attributed to isostatic uplift caused by heating of the lithospheric mantle under the Shield, with significantly higher region along the Red Sea possibly resulting from a combination of lithosphere thinning and dynamic uplift.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 946929
• Report Number(s): UCRL-JRNL-236685
• Journal Information: Geochemistry, Geophysics, Geosystems , vol. 9, N/A, July 25, 2008, Q07020, Journal Name: Geochemistry, Geophysics, Geosystems , vol. 9, N/A, July 25, 2008, Q07020 Vol. 9
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
HEATING
ORIGIN
PHASE VELOCITY
PLUMES
POLARIZATION
RAYLEIGH WAVES
RED SEA
SHEAR
SHIELDS
TOMOGRAPHY
UPWELLING
VELOCITY
VOLCANISM