GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 16-11
Presentation Time: 11:10 AM

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


HARRIS, Ashley1, COVAULT, Jacob A.2, MADOF, Andrew1, BAUMGARDNER, Sarah3, SUN, Tao3, SYLVESTER, Zoltán2 and GRANJEON, Didier4, (1)Chevron, Energy Technology Company, 1500 Louisiana Street, Houston, TX 77002, (2)Bureau of Economic Geology, University of Texas at Austin, Austin, TX 78713, (3)Energy Technology Company, Chevron Corporation USA, 1500 Louisiana St., Houston, TX 77002, (4)Institut Français du Pétrole, Rueil Malmaison, 92506, AshleyHarris@chevron.com

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.