SEPM Strata

accommodation succession

The sedimentary section is composed of complex sets of sedimentary geometries and a complex plethora of different sedimentary facies that have changed their character through time. To help describe and interpret the complexity of the sedimentary section Neal and Abrue 2009 have proposed using a framework for this hierarchy of sedimentary units observed in the stratigraphic section that is based entirely on the geometric relationship of the strata involved. This framework of geometries is assumed to be the result of the repeated fill of accommodation by successions of sedimentary strata. This accommodation and the successions of strata filling it have been named "accommodation successions" by Neal and Abrue 2009. Existing hierarchal frameworks have been modified to describe the depositional units resulting from accommodation successions of varying magnitude and duration, across a depositional profile that are interpreted to be the combined products of changes in rates of base level & rates of sediment accumulation, resulting in successive stratal geometries that:

Prograde and aggrade (PA)
Retrograde (R)
Aggrade to prograde to degrade (APD)

The characteristic geometries of accommodation successions can be used to interpret and differentiate the various systems tracts and sequences listed elsewhere on this site.
In the attached diagram accommodation successions are interpreted to be equivalent to:

These geometric successions are used to guide interpretation of conceptual models using sea level, sedimentation and or/age duration.

References

Neal, J., and Abreu, V., 2009, Sequence stratigraphy hierarchy and the accommodation succession method, Geology, v. 37, p. 779-782