Deformable Plate Model


Extensional and compressional environments vs present day configurations

A problem with traditional plate reconstruction models is the dependency on rigid plate geometries based on present day configurations. However, the palaeo-geometry of plates in extensional and compressional environments is very different from their present day configurations.

Where plates have been stretched by extensional processes such as rifting, overlaps occur when they are reconstructed using rigid plate models to their pre-rift palaeo-positions. Conversely, underfit occurs where plates have undergone compression related to orogenic processes and are subsequently reconstructed.

Deformable Plates

The classification of new deformable plates within the Plate Wizard model has allowed extension and contraction to be modelled at these tectonically active plate margins.

The Plate Wizard software facilitates the reconstruction and prediction of these modified geometries of deformed plate margins in the past by creating a displacement grid that reflects the amount and the direction of the deformation.

The Plate Wizard displacement grid

This is achieved by detailed modelling of the deformation event. The Plate Wizard rigid plate model is used to determine the trajectory of the deformation and the overlap or underfit of the plates is used to calculate beta values. The timing of the extensional or compressional event is interpreted from the rigid plate model and checked against peer-reviewed public domain data sources.

Robertson's internal Plate Wizard administrator tool then uses these beta factors and trajectories to create a deformation model.

The user version of the Plate Wizard tool then analyses the model and applies the appropriate deformation to the user's shapefiles. The two margins are then reconstructed and a new tighter fit is achieved with the overlap or underfit problem eliminated.

To date, this technique has been applied to Mesozoic extensional rifting events at the Atlantic, Southern Australian and Western Indian Ocean margins. The Zagros foldbelt has been modelled to test the validity and accuracy of the modelling and the Plate Wizard software in compressional plate tectonic environments.