Towards a New Genetic Classification of Carbonate Platforms Based on Their Basinal and Tectonic Settings in the Cenozoic

Dan Bosence
Royal Holloway University of London, Egham, Surrey, England

The existing classifications of carbonate platforms into ramps and rimmed shelves have value in describing platform margin morphology at any one time. However they are less successful at categorising the entire morphology and stratigraphy of carbonate platforms. A reassessment of Cenozoic carbonate platforms indicates that their basinal and tectonic setting can be used to erect a first-order, genetic classification of carbonate platforms. The basinal and tectonic setting of carbonate platforms is shown to control their occurrence, the overall 3-D platform morphology, the large-scale stratigraphic features and depositional sequences. Climate, ocean chemistry and biological evolution control grain types, facies and some elements of platform margins but not the larger-scale features. From a review of well-exposed outcropping and seismically imaged Cenozoic platforms, it is proposed that eight types can currently be recognised and characterised based on their basinal and tectonic setting: Fault-Block, Salt Diapir, Subsiding Margin, Offshore Bank, Volcanic Pedestal, Thrust-Top, Delta-Top and Foreland Margin carbonate platforms. These eight types are described using information from Cenozoic platforms worldwide and the controls on their development are discussed. Many platform types (e.g. Subsiding Margin, Offshore Bank, Salt Diapir, Thrust-Top and Foreland Margin) are typical of particular classes of sedimentary basins, others (e.g. Fault-block, Volcanic Pedestal and Delta-Top) are more widespread in their occurrence and occur in a range of basin types. The value of this classification is that it is genetic rather than morphological; the platform models can be used as templates to characterise the details of less well exposed, or seismically imaged platforms.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005