--> Abstract: Models of Cretaceous Carbonate Platform Sequences, by R. W. Scott; #91012 (1992).

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ABSTRACT: Models of Cretaceous Carbonate Platform Sequences

SCOTT, R. W., Amoco Production Co., Tulsa, OK

Cretaceous carbonate platforms developed in a wide range of tectonic settings from passive margins, compressional margins, rift basins, and foreland basins. The combined effects of subsidence and eustatic change controlled the accommodation space between base level and the depositional interface. Climate and paleogeographic position controlled the supply of both carbonate and intercalated terrigenous sediment.

Clues to the controls of carbonate platform sequences are in the architecture of the component stratal surfaces. Important elements are types of stratal surfaces, the relation between stratal surfaces, and the size of the resulting architectural units. Key stratal surfaces are regional erosional or drowning surfaces, transgressive surfaces, maximum flooding surfaces, and internal depositional surfaces. The useful relationships are types of terminations, angle of incidence, and shapes of surfaces and units between surfaces.

Progradation characterizes passive margin carbonate platforms. The thickness of the sequences and rates of progradation are controlled by local intrabasinal tectonics. Sequence boundaries are regionally extensive drowning unconformities. The maximum flooding interval may be either a downlap surface that corresponds with the sequence boundary or a transition from deeper facies to shoaling-up facies. These sequences consist mainly of transgressive and highstand systems tracts. Widespread evaporite intrashelf basins are part of the transgressive systems tracts.

Sediment accumulation rates of the prograding shelf margins generally are faster than in the forereef basin or the carbonate platform. Slowest rates are upon the platforms where numerous hiatuses punctuate the interbedded marl and limestone parasequences that comprise shoaling-up cycles. These cycles are controlled either by short-term sea level changes or by climate.

 

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)