Moho topography and crustal properties in the UAE and northern Oman mountain belt from teleseismic receiver functions

Abstract

SUMMARYThe United Arab Emirates (UAE)-Oman mountain belt exposes a large intact ophiolite thrust sheet that was obducted onto a rifted continental margin during the Late Cretaceous. Crustal properties of the mountain belt and the foreland region are important to better understand the mechanism of crustal deformation during the obduction process. In this study, we analysed P-wave receiver functions across the UAE and northern Oman mountain belt to determine the Moho depths, crustal properties and velocity structure beneath 53 broad-band seismic stations. Crustal thickness varies from 30.0 km in the western UAE to 46.6 km in the UAE-Oman mountain belt. The deeper Moho depth beneath the UAE-Oman mountain belt is the outcome of crustal thickening and flexure of the lithosphere during the obduction process. The eastern flank of the UAE-Oman mountain belt has relatively high-Vp/Vs ratios of 1.76–1.89. On the contrary, comparatively low-Vp/Vs ratios (1.61–1.67) are estimated in the western flank. Moreover, relatively low-Vp/Vs ratios (1.61–1.70) are observed in the foreland basin and western UAE. The high-Vp/Vs ratios and thick crust are indication of a thick ophiolite thrust sheet, while low-Vp/Vs ratios suggest that the crust is more felsic/intermediate in nature. The Vs-depth profiles in the mountain belt reveal a low-Vs zone beneath a remarkably high-Vs top layer. There is no such high-Vs top layer in the foreland area and western UAE. The high-Vs layer is correlated to a ∼10–15-km thick sequence of Semail crust and mantle ophiolite. Common Conversion Point imaging across the UAE-Oman mountain belt imaged the Moho boundary, which agrees with H-k stacking results, and intra-crustal discontinuities.