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Dynamics of Tethyan Carbonate Platforms

Alfonso Bosellini

Tethyan carbonate platforms are relatively short-lived depositional systems which were born, developed, died, and sometime resurrected in a tectonically active area. In contrast with pericratonic platforms, which are generally huge in size (hundreds of kilometers across) and show wide facies belts, very gentle slopes (ramps) and transitional boundaries, Tethyan carbonate platforms are smaller (tens of kilometers) and have steep slopes, generally faulted boundaries, and abrupt facies changes. It appears clear that the overall control on these two contrasting systems is the geodynamic milieu: relatively stable in the first case, where eustatic oscillations and long-term subsidence are probably the main dictators; quite dynamic and "aggressive" in the second one, where carbo ate platforms developed through the entire geodynamic spectrum (rifting, transtension, transpression, and collision) of the Wilson cycle.

Primary controls on Tethyan carbonate platforms appear to be tectonics (most important) and eustatic sea level oscillations, which determine their emplacement, growth, and decay; their overall shape and architecture are a function of these factors.

Secondary factors affecting Tethyan carbonate platform evolution are physiography, oceanographic conditions, and biology as a function of geologic time (especially across the Mesozoic-Tertiary boundary); facies and facies distribution and, to a lesser extent, their shape are controlled by these variables.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.