CICLO DE SEMINÁRIOS DO LABSIS – 7º SEMINÁRIO

Título: The Lithospheric Shear-Wave Velocity Structure of Saudi Arabia

Autor: Zheng Tang

Data: 29 de setembro de 2016 – Horário: 15:30h
Local: Auditório do Departamento de Geofísica (2º pavimento do Prédio REUNI)

Resumo: The lithospheric shear-wave velocity structure of Saudi Arabia has been investigated by conducting H-κ stacking analysis and jointly inverting teleseismic P-receiver functions and fundamental-mode Rayleigh wave group velocities at 56 broadband stations deployed by the Saudi Geological Survey (SGS). The study region, the Arabian plate, is traditionally divided into the western Arabian shield and the eastern Arabian platform: The Arabian shield itself is a complicated mélange of crustal material, composed of several Proterozoic terrains separated by ophiolite-bearing suture zones and dotted by outcropping Cenozoic volcanic rocks locally known as Harrats; The Arabian platform is primarily covered by 8 to 10 km of Paleozoic, Mesozoic and Cenozoic sedimentary rocks. Our results reveal high Vp/Vs ratios at a Cenozoic volcanic area – Harrat Lunayyir, which are interpreted as resulting from solidified magma intrusions from old magmatic episodes in the shield. Our results also indicate slow velocities and large upper mantle lid temperatures below the southern and northern tips of the Arabian shield, when compared with values obtained for the central shield. We argue that our inferred patterns of lid velocity and temperature result from heating by thermal conduction from the Afar plume (and, possibly, the Jordan plume), and that volcanism in western Arabia may result from small-scale adiabatic ascent of magma diapirs.