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

Abstract

Summary The 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 broadband 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 is 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.

Subsidence and Uplift History of the UAE and the Western Flank of the UAE‐Oman Mountain Range

“…Unfortunately, the structural interpretation of the seismic reflection profiles (Figure 5) could not validate these findings due to inadequate resolution in their deeper sections. Moreover, teleseismic receiver function, and gravity and magnetic inversion studies (Ali et al., 2014; Geng et al., 2022a; Ismaiel et al., 2023) on crustal structures and basement evolution did not indicate a coincident crustal thinning in central UAE. Nevertheless, the trend of the stretching factors and the tectonic subsidence maps of the two rift events identified in this study are closely similar (Figure 13).…”

“…More recently, Ismaiel et al. (2023) determined the Moho depth beneath the UAE and the northern Oman mountain belt based on an analysis of teleseismic receiver function data. Their findings suggest a Moho depth that varies from 47 km in the mountain belt to around 30 km in the UAE's central, western, and Arabian Gulf areas.…”

“…Ismaiel et al. (2023) attributed the occurrence of thin continental crust (ca. 22 km + 8–18 km sediment fill) beneath the western UAE and foreland basin to rifting, thinning, and heating of the crust before ophiolite emplacement onto the continental rifted margin.…”

“…This implies, that when a 11-14 thick sediment cover is taken into account, a present depth to Moho of around 30-36 km (Ali et al, 2018;Geng et al, 2022a). Ismaiel et al (2023) attributed the occurrence of thin continental crust (ca. 22 km + 8-18 km sediment fill) beneath the western UAE and foreland basin to rifting, thinning, and heating of the crust before ophiolite emplacement onto the continental rifted margin.…”

Ghost Plumes Hidden Beneath Earth’s Continents

“…After parameterization, 28,413 and 6,175 nodes were contained by the P-and S-wave models, respectively. Depth variations of the Moho discontinuity from receiver functions 51,54 are incorporated in the tomographic inversions. To evaluate the opportune trade-off among the data variance, model variance and model roughness, a so-called L-curve (or trade-off curve) approach is used to determine the optimal damping and smoothing parameters required for inversions.…”