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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

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

Authors :
Olga I. Shelukhina
Mohamed A.K. El-Ghali
Junaid Ahmed Khan
Abdul Razak Al-Sayigh
Mohamed Kh. Khalifa
Iftikhar Ahmed Abbasi
Sankaran Rajendran
Source :
Geological Journal. 56:4254-4279
Publication Year :
2021
Publisher :
Wiley, 2021.

Abstract

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. This work is supported by His Majesty's Trust Fund Grant # SR/SCI/ETHS/15/01 to Sultan Qaboos University (SQU)

Details

ISSN :
10991034 and 00721050
Volume :
56
Database :
OpenAIRE
Journal :
Geological Journal
Accession number :
edsair.doi.dedup.....6bce7d1f9350e0549e8d4875825a9548
Full Text :
https://doi.org/10.1002/gj.4157