Shelf-to-basin sediment transfer mechanisms in contrasted tectonic settings: Insights from quantitative 3D seismic stratigraphy

With ~15% of siliciclastic hydrocarbon reservoirs located in deep-water basins, a key challenge is to predict when and where sands are bypassed to deep-water areas, and how they are architecturally organized. Quantitative 3D seismic stratigraphy (QSS) aims at investigating the linkages between hydrodynamic regime along paleoshorelines, shelf-margin architecture and the development of coeval deep-water systems in a variety of tectonic and climatic settings. This approach is underpinned by state-of-the-art, full-volume 3D seismic interpretation methods that enable high-resolution seismic stratigraphic analysis. Results obtained from shelf margins developed in late syn-rift (Northern Carnarvon Basin, Australia), post-rift (Porcupine Basin, Ireland) and foreland fold and thrust belts (NW Borneo) settings will be presented. Statistical analysis of these data reveals that overall, fluvial-dominated shorelines are typically associated with: (1) slope gradients twice steeper than the wave-dominated shorelines; and (2) longer run-out turbidite systems. However, these relationships become less clear in basins where the slopes are highly affected by tectonics (i.e., ponded slopes) and/or the inherited paleotopography of the basin. Additionally, the turbidite systems developed in NW Borneo present a significant longer run-out distance because the shelf-margin clinoforms are merging with the continental margin clinoforms, thus promoting the development of architecturally more mature turbidite systems along higher and longer slopes. These results highlight that variations from fluvial- to wave-dominated systems represent first-order controls on the coeval development of deep-water systems. However, while shelf-to-basin sediment transfer mechanisms influence slope gradients, inherited paleotopography and tectonics have a direct impact on shelf-margin architecture and associated turbidite systems. By integrating advanced tools in seismic interpretation, quantitative 3D seismic stratigraphy represents a novel approach in assessing at high resolution the controls on deep-water sand delivery, and potentially predicting the type and location of reservoirs in deep-water areas based on shelf-margin architecture and depositional process regime.Open-Access Online Publication: May 29, 202