Use of Sedimentary simulations for dating sequence boundaries and measuring ••.
303
16.5- 15.5 Ma. The beginning of this time period was marked by a drop in sea level which is followed by a marked rise and the beginning of another fall. The same
rates of subsidence were maintained, and the shallow water benthic as well as pelagic showed a decline in accumulation rate.
15.5-14 (13.8) Ma. The sea level rose initially but remained constant in the later
part of this period, aggradation and progradation continued with minor onlap
of the shelf margin. The same rates for subsidence were maintained, while the
rate of accumulation of shallow water benthic as well as pelagic carbonate continued to steadily decline.
14 (13.8)-12.5 Ma. Sea-level falls caused the basin margin to prograde. The same
rates for subsidence and carbonate depositional rates were maintained. No onlap of the shelf margin occurred.
12.5-10.5 Ma. The sea level remained constant before falling drastically at the
end of this sequence. The basin margin showed progradation. The same rates for
subsidence and benthic carbonate accumulation rates were maintained. The pelagic rate dropped to 0.008 m/ka. The 10.5 Ma surface is marked by an erosional
surface.
10.5-6.5 Ma. The sea level continued to fall below the shelf margin and to maintain the match between the seismic and the simulation, the subsidence rate was
increased to -0.03 m/ka at the end of this time period. The same rate of carbonate accumulation was maintained to fill the offshore basin and maintain the correct amount of progradation of the carbonate margin.
6.5-5.5 Ma. The sea level fell a little during this interval and extended the ramplike shallow progradation. The higher rate of subsidence and similar low rate of
carbonate accumulation was maintained to match the previous interval, the simulation was more difficult to match to the seismic because rates of carbonate accumulation were now difficult to tune to produce the correct geometric response.
5.5-4{3.8) Ma. There was a small, gradual rise in sea level. The same rate of subsidence was maintained and the rate of carbonate accumulation remained the
same as in the previous sequence interval. A highly eroded surface was prescribed for the end of this period. This produced a good match in the thickness
for the onlap and aggradational geometries seen on the seismic.
4{3.8)-0 Ma. The thickness or the final basin fill of the shelf was obtained by
keeping the rate of subsidence constant while increasing the rates of pelagic and
benthic carbonate accumulation. The pelagic accumulation rate was increased
to 0.08 m/ka while the shallow water benthic rates returned to the initial high
values.
303
16.5- 15.5 Ma. The beginning of this time period was marked by a drop in sea level which is followed by a marked rise and the beginning of another fall. The same
rates of subsidence were maintained, and the shallow water benthic as well as pelagic showed a decline in accumulation rate.
15.5-14 (13.8) Ma. The sea level rose initially but remained constant in the later
part of this period, aggradation and progradation continued with minor onlap
of the shelf margin. The same rates for subsidence were maintained, while the
rate of accumulation of shallow water benthic as well as pelagic carbonate continued to steadily decline.
14 (13.8)-12.5 Ma. Sea-level falls caused the basin margin to prograde. The same
rates for subsidence and carbonate depositional rates were maintained. No onlap of the shelf margin occurred.
12.5-10.5 Ma. The sea level remained constant before falling drastically at the
end of this sequence. The basin margin showed progradation. The same rates for
subsidence and benthic carbonate accumulation rates were maintained. The pelagic rate dropped to 0.008 m/ka. The 10.5 Ma surface is marked by an erosional
surface.
10.5-6.5 Ma. The sea level continued to fall below the shelf margin and to maintain the match between the seismic and the simulation, the subsidence rate was
increased to -0.03 m/ka at the end of this time period. The same rate of carbonate accumulation was maintained to fill the offshore basin and maintain the correct amount of progradation of the carbonate margin.
6.5-5.5 Ma. The sea level fell a little during this interval and extended the ramplike shallow progradation. The higher rate of subsidence and similar low rate of
carbonate accumulation was maintained to match the previous interval, the simulation was more difficult to match to the seismic because rates of carbonate accumulation were now difficult to tune to produce the correct geometric response.
5.5-4{3.8) Ma. There was a small, gradual rise in sea level. The same rate of subsidence was maintained and the rate of carbonate accumulation remained the
same as in the previous sequence interval. A highly eroded surface was prescribed for the end of this period. This produced a good match in the thickness
for the onlap and aggradational geometries seen on the seismic.
4{3.8)-0 Ma. The thickness or the final basin fill of the shelf was obtained by
keeping the rate of subsidence constant while increasing the rates of pelagic and
benthic carbonate accumulation. The pelagic accumulation rate was increased
to 0.08 m/ka while the shallow water benthic rates returned to the initial high
values.