AAPG Middle East Region Geoscience Technology Workshop

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Meso-Cenozoic Structural Evolution of North Oman Subsurface: The Example of Lekhwair Area


We highlight the role of Triassic-Jurassic extension and late Cretaceous compression during Mesozoic-Cenozoic (Alpine) structuring of the North Oman subsurface. The syn/post-Mesozoic regional structural evolution is traditionally documented as a succession of two stages of deformation. The Alpine 1 phase, late Cretaceous in age, occurred in association with two distinct episodes of ophiolite obduction (Semail and Masirah ophiolites). It is characterised by strike-slip to extensional deformation in the North Oman foreland basin. The Alpine 2 phase, is Oligo-Miocene in age. It is related to the continental collision driving the Zagros orogeny. Alpine 2 deformation was transpressional to compressional. Interpretation of good quality 3D seismic imagery in the Lekhwair High area enabled the distinction of two earlier phases. Early Mesozoic extension occurred concomitantly with the regional Triassic to Jurassic rifting, developing Jurassic-age normal faults. Late Cretaceous compression occurred prior to the main Alpine 1 phase and triggered the inversion of the earlier Jurassic-seated normal faults as well as the initiation of compressional folds in the Cretaceous overburden. These early phases have often been overlooked as part of the North Oman history although they are at the origin of structures hosting major local and regional hydrocarbon accumulations.