When creating a MigriX project, the simulator will attempt to create reasonable timesteps for the simulation run. These are the timesteps where the simulator pauses to show results to the user in addition to the time steps at which input data are loaded. Note however, that MigriX loads data for all timesteps into memory before starting the simulation, and it will also compress entire histories loaded from external sources, e.g. pressure, temperature, burial and oil and gas expulsion.
The model simulation runtimes depend heavily on the number of active timestep. If the model is running slowly, you may consider reducing the number of active timesteps in the early part of the history.
In general, MigriX refers to Ages as positive numbers and times as negative numbers, both typically annotated as Ma for “Mega Annum” or My for “Million years”. We typically specify ages of the Top of layers, which then corresponds to the end of a depositional cycle. An Age of e.g. 65.567 Ma thus refers to 567 000 years before the end of the Cretaceous according to the GTS2004 geologic time scale of Gradstein and Ogg (2004). MigriX also uses the GTS2004 colour scheme to define the colours for the stratigraphy in the Project Workspace.
Figure 3.6: Age and colour scheme for layers
Editing timesteps
You can control which time-steps are used in the Edit Timesteps Table, which will bring up the Timestep editor (see Figure 3.7). In this case, simulation steps at 2, 10, 15, 23, 36, 45 and 77 Ma have been added. Once the time-step definition has been completed, the time-steps can be saved into a new or to the same project. The new definition must be activated in MigriX by clicking on the Update timestep button in the Standard toolbar or in the File menu.
Figure 3.7: The Timestep editor is used to add or remove time steps.
