Abstract: Plate Tectonics and Sedimentary Cycles in Carbonate Rocks

M. Malek-Aslani

The three-dimensional aspects of thick carbonate sequences can be explained best as a sequence of upward-shoaling cycles. A simple upward-shoaling cycle results in the building up of the seafloor by sedimentary processes, followed by progradation. Such sedimentary cycles can explain the depositional mechanism of relatively thin (< 60 ft or 18 m) carbonate beds.

The stretched-upward shoaling cycle, which develops in response to the contemporaneous subsidence, can be used to interpret the three-dimensional geometry of thick carbonate sequences. The stretched and simple upward-shoaling cycles are the building blocks which comprise the transgressive or regressive carbonate sequences. Both simple and stretched-upward shoaling cycles can be recognized in the Mesozoic section of the Gulf Coast region.

Eustatic sea-level fluctuations which can be related to the spreading rate of lithospheric blocks in the context of plate tectonics probably are controlling factors for some major transgressive episodes. However, most of the repetitive cycles are believed to be related to the tensional and shear stresses within the upper brittle layer of the crusts as a consequence of vertical movement within lithospheric plates. This mechanism probably was operative in the sedimentary basins related to divergent, convergent, and transform motions.

AAPG Search and Discovery Article #90967©1977 GCAGS and GC Section SEPM 27th Annual Meeting, Austin, Texas