- Both modeled structural surfaces and horizons are overlain on your seismic or geologic section and represent geological strata.
- You can control the names and display parameters (line thickness and color) in similar fashion.
- However whereas horizon segments are manually drawn and can have arbitrary shapes, modeled structural surfaces are automatically generated through the structural modeling process.
- Interpreted horizons can be used as reference horizons during structural restoration.
- Any displayed structural surfaces are transformed during structural restoration, but the surfaces themselves have no active role.
StructureSolver has three functions for adjusting modeled structural surfaces and the layers between them. These functions can be used on either the footwall or hangingwall of the modeled fault. You can create the same model by using any one of these functions in a series of operations, or by using an arbitrary combination of them in a series of operations. However, depending on the problem you are trying to solve, one or more of these functions may provide the most efficient approach.
- Stretch Overlying Layers allows you stretch (or contract) all the layers above a chosen surface by the same proportional amount. This function is very useful in situations where you suspect that you have pre-growth strata overlain by growth strata. Stretch Overlying Layers is the most efficient technique for creating simple models where the expansion ratio changes in a discrete fashion.
- Move Underlying Layers allows you to control the expansion ratio of the individual layer immediately above the surface that you are displacing, while preserving the expansion ratios of all other layers. There will be no change to the shapes of the surfaces above the surface that you are modifying. The shapes of the surface that you are moving, and all the surfaces below will change. However, the expansion ratios of all the underlying layers will remain the same. This function is useful when you want to model a structure in an incremental fashion from the top down.
- Move Individual Surface lets you move an individual surface on the footwall or hangingwall of a fault. The shape of the surface you are moving will change and the expansion ratios of the layer above and below it will change, but everything else will remain the same. This function gives you fine control of the position of an individual surface on the hanging wall or footwall of a fault.
This will be the case when you have convex bends on steep sections of a fault, or a very shallowly dipping final section of a fault. While you are modifying a fault or a structural surface you can go into fine control mode by holding down the Control key while you are moving points. In this mode the point you are moving will move only one tenth of the distance between its original position and the cursor position.
In this case you will see red circles on fault points. You can use Identify Fault Errors to diagnose the issues.
You will get warnings when the fault trace reverses dip or has a dip that exceeds the deformation shear angle.
Structural Modeling Errors and Warnings