Late Cambrian-Early Ordovician Hybrid-Energy Deltaic System of the Peri-Gondwana Terranes: An Example from the Barik Formation of the Haushi-Huqf Region, Oman

The Barik Formation corresponds to the uppermost part of the Andam Group (Haima Supergroup) and is well exposed in the Huqf region of central Oman. It is a complex, deep, tight gas reservoir in Oman’s interior Salt Basin and has been previously interpreted as braid delta deposits. This study illustrates a detailed outcrop-based stratigraphic and facies analysis of the Barik formation in the Huqf region. It offers new insights into the spatial and temporal distribution of the depositional facies and provides more information to enhance the depositional environment interpretation of the Barik Formation in the outcrop. The results revealed a complex depositional system indicated by various lithofacies, which have been grouped to represent four facies associations, including (i) mouth bar/shoreface, (ii) tidal flat, (iii) tidal channel, and (vi) delta distributary channels. The mud drapes, large-scale reactivation surfaces, sigmoidal cross-bedding, climbing ripples, and flaser bedding indicate tidal flats and delta distributary channels of the lower delta plains. Wave and storm facies, including wave ripples and small-scale hummocky cross-stratification, represent a mouth bar/shoreface of the delta front depositional setting. The presence of basal scouring surfaces with lag deposits at channel bases and desiccation cracks of red mudstones indicated fluvial and subaerial facies. This study serves as an analogue for the ancient hybrid energy prograding delta over a broad and low relief shelf in a vegetation-free system, where the deposition is controlled by an interplay of multi-related tidal, wave/storm, and fluvial processes.