Three-dimensional seismic data from the Torosa Field (Torosa 3D Survey) in the Browse Basin of the Northwest Shelf, Australia, display a series of well imaged isolated carbonate platforms that allow the documentation of platform evolution from initiation to terminal drowning. The application of seismic geomorphology allows recognition of various carbonate geomorphic elements (depositional and diagenetic) including prograding margins, slope deposits, platform interior patch reefs, and karst fabrics. A variety of techniques integrating seismic geomorphology and seismic stratigraphy have been applied to assist in visualization of these deposits. Examples of workflows and techniques including horizon slicing, optical stacking, and facies mapping, along with the integration of seismic section views (i.e., stratigraphy) and plan views (i.e., geomorphology) will be illustrated.
This presentation will focus on the lower part of the carbonate succession. The carbonate factory is initiated through nucleation on a subtle pre-existing structural high. Initially, the carbonate system is characterized by a platform characterized by linear margins associated with progradation marked by clinoform architecture in both directions, suggesting an isolated platform with no direct connection to the Australian continent. An initial ramp style platform gradually gives way to a platform bounded by progradational slope physiography. The platform margin is characterized by reefal buildup repeatedly crosscut by channels that connect the open ocean with the interior platform. Within the interior of the platform small patch reefs and occasional seaways are common. Several flooding events punctuate the platform evolution, with each drowning event immediately preceded by deposition of clusters of small patch reefs, less than 300m wide.