EQUIFINALITY IN DEEP-WATER SAND DELIVERY: INSIGHTS FROM 3-D STRATIGRAPHIC FORWARD MODELS

Eustasy constitutes a key control on continental-shelf accommodation. In order to test the effects of eustatic variation on deep-water sediment delivery rates, we ran two models; one using the New Jersey Margin derived eustatic curve, and the other a base case with no imposed change in eustatic level. We found that the change in eustatic curves resulted in a 0.9% difference in cumulative deep water sand volumes between models. In the eustatic model, maximum deep-water sand accumulation occurred during short-term sea-level falls, but peak sand delivery did not correspond well with the magnitude of the sea-level fall and the timing of peak deep-water sand delivery during falls was highly variable. Further examination of the relationship between rates of relative sea level and deep-water sand delivery show a poor correlation (r² < 0.1). Large and small amplitudes of sea-level change produced identical magnitudes of deep-water sand delivery. Deep-water sand delivery events of similar magnitude were also observed in the no-eustatic-variation model, thus accounting for the relative invariance to eustatic curve. Overall, this study suggest that the magnitude and timing of peak deep-water sand delivery during sea-level falls may be unpredictable and that autogenic and allogenic processes may be indistinguishable in the geologic record.