Abstract
AbstractThe Semail ophiolite, a thick thrust sheet of Late Cretaceous oceanic crust and upper mantle, was obducted onto the previously rifted Arabian continental margin in the Late Cretaceous, and now forms part of the United Arab Emirates (UAE)‐Oman mountain belt. A deep foreland basin along the west and SW margin of the mountains developed during the obduction process, as a result of flexure due to loading of the ophiolite and underlying thrust sheets. The nature of the crust beneath the deep sedimentary basins that flank the mountain belt, and the extent to which the Arabian continental crust has thickened due to the obduction process are outstanding questions. We use a combination of active‐ and passive‐source seismic data to constrain the stratigraphy, velocity structure and crustal thickness beneath the UAE‐Oman mountains and its bounding basins. Depth‐migrated multichannel seismic reflection profile data are integrated in the modeling of traveltimes from long offset reflections and refractions, which are used to resolve the crustal thickness and velocity structure along two E‐W onshore/offshore transects in the UAE. Additionally, we apply the virtual deep seismic sounding method to distant earthquake data recorded along the two transects to image crustal thickness variations. Active seismic methods define the Semail ophiolite as a high‐velocity body dipping to the east at 40°–45°. The new crustal thickness model presented in this work provides evidence that a crustal root is present beneath the Semail ophiolite, suggesting that folding and thrusting during the obduction process may have thickened the pre‐existing crust by 16 km.
Highlights
The complex structure and rocks of the United Arab Emirates (UAE)-Oman mountain belt (Figure 1) have been crucial for the understanding of fundamental questions related to ophiolite obduction and mountain building processes (e.g., Glennie et al, 1973; Searle, 2019; Searle & Cox, 1999)
The well exposed thrust sheets of oceanic crust and upper mantle of the Semail ophiolite have helped decipher the composition of oceanic lithosphere, and investigate how more dense oceanic lithosphere can be emplaced onto more buoyant continental margins (e.g., Pearce et al, 1984; Searle & Malpas, 1980)
Over the past 50 years or so, geologists have concentrated research on the Semail ophiolite, on its original tectonic setting and processes operating during its emplacement onto the UAE-Oman continental margin
Summary
The complex structure and rocks of the UAE-Oman mountain belt (Figure 1) have been crucial for the understanding of fundamental questions related to ophiolite obduction and mountain building processes (e.g., Glennie et al, 1973; Searle, 2019; Searle & Cox, 1999). The well exposed thrust sheets of oceanic crust and upper mantle of the Semail ophiolite have helped decipher the composition of oceanic lithosphere, and investigate how more dense oceanic lithosphere can be emplaced onto more buoyant continental margins (e.g., Pearce et al, 1984; Searle & Malpas, 1980). Over the past 50 years or so, geologists have concentrated research on the Semail ophiolite, on its original tectonic setting and processes operating during its emplacement onto the UAE-Oman continental margin. Mainly in the form of shallow reflection profiles, have allowed the sedimentary sequences in the foreland basins
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