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

Olga I. Shelukhina*, Mohamed A.K. El-Ghali, Iftikhar Ahmed Abbasi, Junaid Ahmed Khan, Mohamed Kh Khalifa, Sankaran Rajendran, Abdulrazak Al-Sayigh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)4254-4279
Number of pages26
JournalGeological Journal
Volume56
Issue number8
DOIs
Publication statusPublished - Aug 2021
Externally publishedYes

Keywords

  • ancient
  • Andam Group
  • Barik Formation
  • fine-grained
  • hybrid-energy delta
  • Oman

ASJC Scopus subject areas

  • Geology

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