Facies architecture and depositional model for a fine-grained hybrid-energy delta: An example from the Upper Cambrian to Lower Ordovician Barik Formation, Central Oman
AuthorShelukhina, Olga I.
El-Ghali, Mohamed A.K.
Abbasi, Iftikhar Ahmed
Khan, Junaid Ahmed
Khalifa, Mohamed Kh
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Recognizing ancient deltas' depositional architecture is challenging due to the complex interplay of the fluvial, waves, and tidal processes. The integration of field-based sedimentological and trace fossils studies of the Late Cambrian-Early Ordovician Barik Formation in Central Oman allowed better identification of different lithofacies architectures and depositional process signatures. The Barik Formation is a major tight-gas reservoir in the Oman Sedimentary Basins, where it is over 800-m thick. The only outcrop analogue is in the Qarn Mahatta Humaid area, where ca. 50-m thickness of the formation is exposed and extends laterally over 5 km. This study revealed the presence of four lithofacies associations, including (a) mouth bar/shoreface, (b) tidal flat, (c) tidal channel, and (d) delta distributary channels using 12 logged sections. The depositional features identified in the field include tidal, wave/storm, and fluvial. The tidal signatures are represented by mud-drapes, large-scale reactivation surfaces, sigmoidal cross-bedding, and climbing and flaser bedding, predominantly in the mixed mud-sand tidal flats of the lower delta plain and delta distributary channels of the upper to lower delta plains. The wave/storm signatures are represented by wave ripples and small-scale hummocky cross-stratification in the mouth bar/shoreface of the delta front platform. The fluvial and subaerial signatures are represented by the occurrence of the scour surfaces with lag deposits of channel-fill and the development of desiccation mud-cracks. The Barik Formation delta sandstones form amalgamated sheet-like bodies prograding to the north-northeast and deposited along a ramp-type low relief basin. This prograding delta represents a highstand system tract. This study presents an example of the ancient fine-grained hybrid-energy prograding delta, where fluvial processes operated beside the tidal and wave/storm processes over a broad and low relief shelf in a vegetation-free system.
- Earth Science Cluster [70 items ]