Facies and integrated sequence stratigraphy of an Epeiric Carbonate Ramp Succession: Dhruma Formation, Sultanate of Oman

Abstract

As an example of an epeiric carbonate ramp depositional system, the worldclass outcrops of the Middle Jurassic Dhruma Formation were studied in the Oman Mountains (Sultanate of Oman). An integrated approach was followed: facies analyses were combined with quantitative sequence-stratigraphic methods as well as bio-and chemostratigraphy. Depositional environments range from peritidal to lagoonal and 'shoal-like' environments. A conspicuous four-level hierarchy of cyclicity was identified. This is substantiated by facies trends and specific cycle indicators such as various types of discontinuity surfaces, biofacies changes, and a suite of quantitative-and semi-quantitative sequencestratigraphic methods like facies stacking pattern plots, facies percentage, bedthickness and bio-component diversity plots, as well as diagrams representing the environmental range and facies belt width per high-frequency sequence. Potential reservoir facies are present in the form of peloidal and oolitic grainstones; potential baffle/seal facies as vastly extensive mudstones and marls. A transition from peritidal to low-energy lagoonal deposits to increasingly highenergy deposits can be observed towards the top of the Dhruma Formation representing a landward shift of the depositional environment. This study may be useful as outcrop analogue for the hydrocarbon-bearing parts of the Dhruma in the subsurface of the Arabian Plate and for similar epeiric carbonates elsewhere.

Cyclicity and hierarchy in sequence stratigraphy: an integrated approach

“…Since the recurrence of sequences does not establish a random pattern, the consequent upward trend is also an important criterion to be observed (e.g., Schlaich and Aigner 2017). Upward trends of stacking patterns occur due to short-term modulation by long-term processes in changes in the A/S ratio (accordion effect).…”

Sedimentology and stratigraphic architecture of a fluvial to shallow-marine succession: The Jurassic Dhruma Formation, Saudi Arabia

“…The Arabian plate, which formed part of the northeastern margin of the Gondwana supercontinent, experienced diastrophic tectonic events throughout much of its geological history (Haq et al, 1988;Haq and Al-Qahtani, 2005;Faqira et al, 2009;Stewart, 2016). In the Permian, it was located at approximately 25° south of the paleoequator, before it progressively shifted northwards during the Triassic and Jurassic (Scotese, 2001;Ziegler, 2001;Schlaich and Aigner, 2017) to occupy a position close to the equator during the Mesozoic (Stampfli and Borel, 2002;Golonka, 2007;Seton et al, 2012;Stewart et al, 2016). This shift of position was accompanied by events that influenced the geology of the Arabian Plate.…”

The Dynamics of the Developing Calcarenite Member of Pamutuan Formation In Cintaratu Area, Pangandaran, West Java

“…A description of the outcrop intends to identify major features, such as bedding plane, gradation, sedimentary structure, fossils and geometry [7], [8]. Microscopic observation on texture, composition (percentage of fragmented and/or non-fragmented shells, the percentage of micrite and terrigenous material, grain size composition), allochem type, diagenetic and microfossils content provide guidance on finding carbonate facies, index energy, sequence stratigraphy and depositional environment [9]- [11]. Field investigation and microscopic observation have been applied to facies and depositional interpretation of ancient carbonate several basins in Asia [8]- [10], [12], [13], including Indonesia [14].…”