Impact of eustatic amplitude variations on shelf morphology, sediment dispersal, and sequence stratigraphic interpretation: Icehouse versus greenhouse systems

The Pliocene-Pleistocene icehouse stratigraphic record is characterized by distinct sediment distribution patterns and chronostratigraphic relationships resulting from high-frequency, high-amplitude changes in sea level. These modern relationships are often used as a template for sequence stratigraphic interpretation and for predicting sediment distribution in ancient greenhouse systems, deposited at times when sea-level fluctuations are known to have been different from the most recent period of geologic time. Numerical modeling suggests that the depth of the shelf rollover, and thereby also shelf accommodation, rapidly adapts to changes in eustatic amplitude along passive, constructional sedimentary margins. Lower amplitudes and perhaps also lower frequencies during greenhouse periods would allow across-shelf delta progradation and sediment delivery to the slope and basin floor during both third-and fourth-order highstands. Care should therefore be taken when extrapolating stratigraphic models between icehouse and greenhouse systems.