--> Basin Scale Typing of Deepwater Sediments, Dattilo, Paolo, #90100 (2009)

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Basin Scale Typing of Deepwater Sediments

Dattilo, Paolo1

1E&P/Geosciences Technology, Total S.A., Pau, France.

General deep water depositional models are fundamental to understand the evolution of a gravity flow and the global distribution of the depositional elements between slope and basin floor. Practical experience suggests however that it is not a good practice to export the architecture of a deep water system across different settings. The massive increase in the last 20 years of the deep water E&P activity and the consequent spread of outcrop studies in various settings provide some foundation to attempt a generalisation. After a first review, the number of key setting types appears quite small, and it could be limited to 3: Passive margins, Intracratonic basins and Confined troughs. Although very different between them, so much that they are barely comparable, the same system type in various part of the world tends to show a good set of similar features. The key building elements of a deep water system, like canyons, channel-levee systems or basin floor fan appear to be present in all settings. But relative proportions, distribution and sizes vary enormously. For example, the passive margins systems are essentially made of channel-levee elements, but these elements may have a very limited expression in confined foredeep basins. Basin floor elements of Intracratonic basins could be at a walking distance from their feeding deltas, while it may take several hours for a vessel in the Gulf of Mexico to cover the distance. Examples throughout the world will be presented to illustrate the main distinctive features. Confined systems, like foredeeps, are characterised by relatively minor canyon and channel-levee development, widespread unconfined lobes, and ubiquitous chaotic sediments. Most of the channel-fill elements are smaller and less complex than in the large passive margins. Dominant sandy facies in Confined basins is represented by even, parallel beds with “Bouma sequences”. In Passive margins, large channel - levees elements dominate the panorama down to the abyssal plain and contain highly complex channel-fill bodies. Sheet systems are occasionally developed, in particular in coincidence with major tectonic events. Intracratonic basins are essentially lacking of significant preserved channel-fill features, and they lay very close to their feeding deltas. They are essentially made up of unconfined lobe systems at the toe-set of prograding clinoforms. They may display evidences of flood sedimentation and local hint of wave reworking.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil