The Hawasina Nappes: stratigraphy, palaeogeography and structural evolution of a fragment of the south-Tethyan passive continental margin

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Abstract
Lithostratigraphic and biostratigraphic revision of the Hawasina Nappes in the eastern and central Oman Mountains, including the redefinition of the Hamrat Duru Group and the definition of the three new groups, the Al Aridh, Kawr and Umar Groups, has led to a new interpretation of the palaeogeographic and structural evolution of the south-Tethyan continental margin. Margin history began in the Late Permian with a phase of extension and rifting, accompanied by considerable magmatic activity, and led to the development of the Hamrat Duru Basin separating the Arabian Platform to the south from the Baid Platform to the north. In the Middle to Late Triassic renewed extension led to rifting, again accompanied by important magmatic activity, with the break-up of the Baid Platform, and the development of the Al Aridh Trough, the Misfah Horst and the Umar Basin. These Permian and Triassic tectonic units together constituted the Hawasina Basin. A third phase of extension during the Late Tithonian—Berriasian caused a general foundering of the continental margin. The development of the Hawasina Basin terminated in the Santonian, when compression initiated the first stage of obduction that closed the basin. Ongoing obduction, during the Campanian, led to thrusting of the Hawasina and the Samail ophiolite nappes onto the Arabian Platform by gravitational mechanisms.