--> --> Deformation Patterns of Neoproterozoic and Earliest Cambrian Rocks at the Western Sector of the Jabal Akhdar Dome, Central Oman Mountains

AAPG Middle East Region Geoscience Technology Workshop

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Deformation Patterns of Neoproterozoic and Earliest Cambrian Rocks at the Western Sector of the Jabal Akhdar Dome, Central Oman Mountains

Abstract

This work aims to improve the understanding of Paleozoic tectonic events that affected the Neoproterozoic and Early Paleozoic rocks of the western part of the Jabal Akhdar Dome in Oman (Central Oman Mountains). This sedimentary sequence forms the oldest cover of the Arabian platform with an age ranging from the Cryogenian to the earliest Cambrian. The weakly metamorphosed rocks are truncated by an angular unconformity and re-covered by Permo- Mesozoic sedimentary rocks of the Arabian passive margin. The younger cover was only deformed under brittle conditions and shows gentle, open folding which differs in style and intensity of deformation of the more polyphase folded Neoproterozoic-Cambrian rocks. In the western part of the Jabal Akhdar Dome (in Wadi Bani Awf and Wadi Sathan), two Paleozoic folding phases/events have been identified. Evidence for an older Paleozoic deformation (D1) has been identified within black fetid limestone of the Hajir Formation. These rocks have been deformed in a ductile way, as shown by tight to close apparent cylindrical folds (F1). The structural style reconstructions show a uniform vergence to the NE of the F1 folds, overprinted by a second event (D2). This younger event has refolded the F1 fold axes in open to close folds (F2) with an amplitude of one kilometer. The F2 folds are reclined with fold axes plunging ENE-ward with about 50° and SW-ward with about 30° at the northern and southern side of the Jabal Akhdar Dome, respectively. F2 axial planes dip sub-vertically to the NNW. F2 folds have been recognized/described by previous authors while the F1 folds are a new result of this study. Towards the east, the fold amplitudes and wavelengths are reduced. In the eastern Jabal Akhdar Dome, only minor (D2) folding can be observed.