Stratigraphic architecture of a Late Cretaceous turbidite system (Puffin Formation), Vulcan Sub-basin, North-West Shelf, Australia

The stratigraphic evolution of the Cretaceous Puffin Formation was investigated through the interpretation of 2D and 3D seismic surveys, integrated with wireline, biostratigraphic and sedimentological (core) data. The study outlines the development of a prograding delta succession and linked turbidite system during the Late Cretaceous (Aptian – Maastrichtian). Clastic influx was driven by tectonic uplift of the hinterland, and sediments were transported by fluvial systems to a shelf-edge delta complex. Basinward sediment transport was achieved by an extensive network of submarine channels, transporting sediments approximately 50 km downslope. The depositional system is broadly interpreted as a multi-source sand-rich turbidite ramp directly fed by the delta complex. Channel belts form initially W trending narrow linear morphologies, before the development of an extensive W-NW trending vertically stacked channel belt complex in the Late Cretaceous. Basinward sediment gravity flow processes are dominated by coarse-grained turbidity currents characterised by relatively short (~50km) run out distances. Waning of sediment supply in the latest Cretaceous (interpreted as the result of a return to low tectonic activity and passive margin conditions) resulted in basin-wide transgression and shutting off of the Puffin delta-turbidite system.

This work presents new insight on the evolution of the Puffin Formation, and highlights the development of a significant delta-turbidite system in the Vulcan Sub-basin during the Late Cretaceous. The stratigraphic architecture and mapping of depositional elements provided in this study can be useful for future exploration in this hydrocarbon bearing formation. Additionally, this study suggests that a phase of renewed tectonic activity occurred along northern Western Australia in the Late Cretaceous, hence providing the source for the Puffin sands accumulated in the Browse and Bonaparte basins. This brings new insights into the understanding of post-rift tectonics along the margins of the North-West Shelf. Lastly, this study provides an additional analogue for the Cretaceous turbidite reservoirs of the North-West Shelf.