Tectonic Controls on Carbonate Platform and Slope Depositional Systems through the Phanerozoic

It has long been known that the location of carbonate platforms may relate to an underlying structural or tectonic control. Tectonic processes are found to be a first-order control on overall platform morphology, margin and slope systems and stratigraphic geometries; whilst changes in carbonate factory, due to environment and biological evolution, are important controls of grain types, facies and pore systems.

This contribution explores, for the first time, the tectonic controls on Phanerozoic carbonate platforms through an investigation of platforms; their margins and slopes in different structural/topographic settings. A new searchable relational database contains information on 320 well-studied carbonate platform systems. This database classifies platforms developed on the following structural and topographic elements; Tilted Fault-Blocks, Horst Blocks, Thrust-tops, Folds, Volcanic Pedestals, Delta-tops, Salt Diapirs and Inherited Topography and within different basin types. Tectonic processes, geological age and carbonate factory are also considered. Petroleum systems data for a set of subsurface platforms (111) comprises field size, hydrocarbon column height, volume and net-gross values.

This review of Phanerozoic platforms indicates that geotectonics, as well as 1st-order eustasy play an important role on platform abundance. Regional plate tectonic episodes control occurrence of different structural classes of platforms. Whilst euphotic carbonate platforms dominate, microbial factories peak in the Palaeozoic and following extinction events, whilst pelagic platforms develop in post-Jurassic times. Cool-water platforms are largely restricted to passive margin, intracratonic and foreland basins. The review shows that physical accommodation is more important than carbonate factory type in controlling platform abundance. Length - width data shows that most platforms are equant but that Tilted Fault-block and Thrust-top platforms are more elongate and that elongate platforms are commonest in Foreland Basins. The thickest platforms occur on Fault-blocks, Volcanic Pedestals and over Inherited Topographies in Passive Margin, Mature Ocean and Rift-Back Arc basins.

Hydrocarbon field abundance follows the above trends with a dominance of reservoirs in platforms on Fault-blocks and over Inherited Topography and that field size relates to structural platform types.
 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California