Forward
Sediment Modeling
of Carbonate Platform Growth and Demise,
Hughes, Tina M.1, Toni Simo2,
John Bova3, Amy Ruf4, Fiona Whitaker5 (1)
ExxonMobil, Houston, TX (2) University of Wisconsin, Madison, WI (3) ExxonMobil,
Houston (4) ExxonMobil, Houston, (5) University of Bristol, Bristol, United
Kingdom
Interactions between tectonism, eustasy,
carbonate accumulation rate, and environmental stresses impact the nucleation,
growth and demise of carbonate platforms. A Miocene carbonate platform from the
seismic
dataset was selected to quantitatively investigate the interaction
between these parameters in controlling carbonate platform evolution using the
forward sediment
modeling
program CARD3D+. Analysis of a series of 3D
seismic
discontinuity time slices flattened on the platform base reveals that the
platform originated from seven nucleation mounds, each 400-1200m in diameter.
The mounds grew concentrically and amalgamated sequentially to form a single
isolated platform 7km in diameter and 300m thick. The platform top is a high
amplitude
seismic
reflector, marking the influx of siliciclastics and the
demise of the platform.
We simulated accumulation of sediment on
an initial surface with seven mounds which match the size, geometry, and
distribution observed in the discontinuity seismic
data. Relative sea level,
controlled by subsidence and eustacy, and carbonate accumulation rates,
controlled by production, restriction, currents and winds were varied to
provide a match to
seismic
data. Reduction of the rates of platform top
sediment production (simulating increased environmental stress) leads to
platform drowning. This suggests the demise of the platform results from the
interaction between increased accommodation, generated by tectonic subsidence
and eustasy, and environmental stresses (influx of siliciclastics). This work
has important implications for carbonate exploration where only 2D
seismic
data
are available for imaging carbonate platforms and for predicting whether a
platform has drowned or backstepped.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California