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

Abstract

The western flank of the UAE‐Oman mountain range offers a unique geodynamic setting to study the development of a cratonic rift into a mature passive margin and its subsequent flexure under orogenic load. However, the geodynamic processes driving this evolution are not fully understood. In this study, seismic and biostratigraphic data from 283 exploration wells were utilized to assess the regional subsidence and uplift history of the United Arab Emirates (UAE) and neighboring areas of the western flank of the UAE‐Oman mountain range. Three major sequences have been identified: pre‐Permian, Permian‐Turonian rifted margin, and Coniacian‐Pleistocene active margin. Backstripping of biostratigraphic data reveals Early Permian (ca. 272 Ma) and Late Jurassic (ca. 160) rift phases, that have been linked to Gondwana's early and final fragmentation. A NE‐SW‐oriented basin in central UAE suggests a Jurassic intracratonic rift that has been influenced by pre‐existing structures. Compressional phases were identified during the Late Cretaceous and in the Oligocene‐Miocene, Compressional phases were identified during the Late Cretaceous and in the Oligocene‐Miocene, coinciding with the emplacement of the Semail ophiolite and the Arabian‐Eurasian plates collision, respectively. These events caused additional subsidence and flank uplift, forming the Aruma foreland basin in the east and the Pabdeh foreland basin in the eastern and northern UAE. Crustal thickness following the rift episodes ranges from 30 to 36 km, considering a sedimentary cover thickness of 11‐14 km. These estimates are in accord with Moho depths derived from teleseismic receiver functions and gravity inversion. These findings can be used to better understand Gondwana fragmentation and the opening and closing of the Neo‐Tethys Ocean.

Discriminating Lithospheric and Asthenospheric Anisotropy Beneath Northern Oman: Sharp Contrast Observed at the Semail Gap Fault Zone

“…The study area is located at the northeastern edge of the Arabian plate (Figure 1a), composed of Neoproterozoic island arcs formed during the Pan‐African orogeny (Allen, 2007; Cozzi et al., 2012). As a result of opening of the Neotethys Ocean, the northern Oman (located in the former Gondwana terrane) experienced rifting (Ali et al., 2013; Ali & Watts, 2009; Jabir et al., 2023) and passive margin tectonics (Pillevuit et al., 1997; Ruban et al., 2007) during the Late Carboniferous. This tectonic evolution was followed by the obduction of the Semail Ophiolite in late Cretaceous (e.g., Tippit et al., 1981), and post‐obduction processes, including late Eocene extension which led to the uplift of Oman mountains (Ninkabou et al., 2021; Weidle et al., 2023).…”

“…The subsurface structure beneath the study area has undergone multiple phases of deformation during various geological periods since the Permian breakup of Pangea (e.g., Ali et al., 2013; Jabir et al., 2023; Ninkabou et al., 2021). Regional‐scale tomographic images (e.g., Pilia, Hu, et al., 2020; Pilia, Jackson, et al., 2020; Shad Manaman et al., 2011) illustrate a transition from thick to thin crust across the northern Oman from west to east.…”

“…Two major tectonic events had left their mark before the obduction of the Semail ophiolite, the extensional Neoproterozoic assembly of Gondwana followed by compressional foreland basin as a result of the Permo‐Triassic breakdown of Pangea (Ali et al., 2013; Jabir et al., 2023). Both these events are reflected in today's lithospheric architecture in northeast Arabia.…”

“…Hence, exploring seismic anisotropy can shed light on the evolutionary processes in the lithospheric mantle. Northern Oman is a continental margin that has experienced an extensive developing process of orogeny, rifting and basin formation (e.g., Ali et al., 2013; Jabir et al., 2023; Searle & Cox, 1999). There is, therefore, a strong likelihood that seismic anisotropy is present due to “fossil” fabrics preserved in the lithosphere, shearing at the base of the lithospheric plate related to present‐day plate motion and local sub‐lithospheric mantle convective flow, or a combination of these mechanisms.…”