Tectono-Stratigraphic Models for Phanerozoic Carbonate Platforms
The traditional morphological classification of carbonate platforms utilises margin geometry to designate examples as rimmed shelves or ramps. It is less successful at describing overall platform morphology and evolution and provides little explanation for temporal and spatial platform evolution. Bosence (2005) used the morphology and stratigraphy of Cenozoic examples to categorise platforms into one of 8 types based on their basinal and tectonic setting. The study postulated that in the Cenozoic, basinal and tectonic processes exerted a 1st order control on platform occurrence, overall 3-D morphology, large-scale stratigraphic features and depositional sequences. A major advantage of this classification is that it can be applied to understand details of less well exposed or seismically imaged platforms, enabling them to be characterised in terms of tectono-sedimentary processes.
The original scheme has been modified to account for changes to carbonate platforms during their lifespan and extended through the Phanerozoic. To aid classification the scheme now records different developmental stages of a carbonate platform (time-slices). Additionally, new classes have been added to account for variations in structural types, sedimentary basin types, tectonic processes and activity rates that may have influenced the evolution of a platform.
To test the robustness of this new scheme, a compilation and review of well-known outcropping and subsurface examples is being undertaken. The resulting dataset is a searchable, process-based, semi-quantitative database of Phanerozoic carbonate platforms. The database contains over 200 examples that can be interrogated to establish: (i) whether the 8 types from the Cenozoic study were present during the Mesozoic and Palaeozoic (ii) if new types can be identified from the geological record or (iii) if time specific models controlled by biological or oceanographic evolution are required to characterise platforms from the ancient past.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009