The fundamental difference between CaCO3 sedimentation and clastic sedimentation is that the magnitude of the CaCO3 source term is dependent on water depth and CaCO3 sedimentation can occur anywhere along the cross-section being modeled. In contrast, clastic sedimentation is defined by an input flux on the left-hand or right-hand side of the model. In either case, material is redistributed by slope-dependent diffusion. See Gildner and Cisne (1990) for more details.
Two carbonate deposition algorithms are possible and can be mixed (i.e. can be specified at different locations on profile): epeiric sedimentation (Equation 2, Figure 4a) and oceanic sedimentation (Equation 3, Figure 4b). The oceanic algorithm has a cut-off value (lag-depth) above which sedimentation rate is a constant value (C1). Setbasin has a facility (explained therein) to allow you to view the shape of the curves defined by each carbonate equation with your parameters:
Equation 2: Epeiric (exponential-depth) sedimentation, where c1 is the `epeiric CaCO3 maximum sedimentation rate' and w0 is the `epeiric CaCO3 depth of the maximum sedimentation rate.' See Gildner and Cisne (1990) for a detailed explanation.
Equation 3: Oceanic (lag-depth) sedimentation, where c1 is the `oceanic CaCO3 maximum sedimentation rate'; c2 is the `oceanic CaCO3 exponential decay constant'; w0 is the `oceanic CaCO3 depth of maximum sedimentation rate.' See Gildner and Cisne, 1990.
Figure 4.a,b: Displays of the functions used for epeiric and oceanic sedimentation in the model. Each different depths of maximum sedimentation rate (w0) of 10 and 100m.
We illustrate two carbonate examples of the oceanic carbonate deposition model. First, we illustrate the generation of a steady-state shelf break (Figure 5a) and second we illustrate the same setting with the addition of a 25 m sinusoidal sea-level change with a period of 4 million years (Figure 5b).
Example of a simple carbonate file (oceanic.carb, Figure 5.a,b):
| 0 | O | 0 | 0 |
and a more complex file:
| 0 | E | 0 | 0 |
| 10e3 | O | 5 | 0 |
| 20e3 | N | 0 | 0 |
Carbonate file notes:
1) The first column is the horizontal position
2) The second column is type of carbonate deposition: E, epeiric, O, oceanic,
N, neither
3) The third column is the lagtime
4) The fourth column is the lagdepth
Figure 5.a: & Figure 5.b Displays of carbonate sedimentation without (carb_noeu.dat - set skip lines to 4 and vertical exaggeration to 50 ) and with (carb_eu.dat) eustatic sea level change. Carbonate file oceanic.carb was used to generate the carbonate sedimentation in both simulations.
