Alexander Robert Blanchette , Simon Klemperer, Walter D Mooney, Hani M Zahran

We analyzed P-wave receiver functions from seismic stations covering most of Saudi Arabia to map the thickness of the crust across the Arabian plate. We present an update of crustal-thickness estimates and fill in data gaps for the western shield and the rifted margin at the Red Sea, as well as the eastern Arabian platform. Our application of a conventional H-k stacking algorithm included careful attention to stacking weights, two forms of sedimentary corrections for stations located on the Arabian platform, and additional processing for noisy stations. Average crustal thickness (i.e. depth to Moho below surface) beneath the Red Sea coastal plain (the rift margin) is 29 km, beneath the volcanic harrats is 35 km, the shield (excluding harrats) is 37 km, and the platform is 38 km. Crustal thinning appears not to extend east of the rift escarpment, suggesting uniform extension, that is no broader at depth than at the surface. In contrast to some previous claims that the platform crust is thicker than the shield, we find no statistically significant difference between whole crustal thickness of the Arabian shield and platform. However, the average sub-sedimentary crustal thickness (i.e., the crystalline crust) of stations on the platform is 34 km, 3 km thinner that the crust of the shield. Individual station Vp/Vs wavespeed ratios are highly variable for the Arabian plate, ranging from 1.60 to 1.97 and averaging 1.75, with a standard deviation of 0.07. There are no statistically significant differences between Vp/Vs ratios of the different geologic regions of Arabia. Similar Vp/Vs ratios, coupled with similar crustal thicknesses for harrats and shield, imply that Cenozoic magmatism has contributed negligibly to crustal growth.