Project Results Cont.
Shear Strain Components
Below are contour maps of the strain components (pure shear strain and simple shear strain) during each epoch of terrane accretion. The two components are calculated using the following formulas:

Pure Shear Strain

g1 = dDx/dx - dDy/dy

Simple Shear Strain

g2 = dDx/dy + dDy/dx

Where:

Dx = dispalcement in x

Dy = displacement in y
Epoch 1: Time step between photos 1 and 2 from the geology section. Top: Pure Shear Strain component. Bottom: Simple Shear Strain component. Note that the strain is dominated by the simple shear component during this time step. The velocity field is superimposed and represented by the arrows.
Epoch 2: Time step between photos 2 and 3 from the geology section. Top: Pure Shear Strain Component. Bottom: Simple Shear Strain Component. Note that the strain in this epoch is still dominated by the simple shear component. The velocity field is superimposed and is represented by the arrows.
Epoch 3: Time step between photos 3 and 4 from the geology section. Top: Pure Shear Strain Component. Bottom: Simple Shear Strain Component. Note the decrease in the focussing of the simple shear component relative to the first two epochs. This time period covers the initial collision between the wedge and the terrane. The velocity field is represented by the arrows.
Epoc 4: Time step between photos 4 and 5 from the geology section. Top: Pure Shear Strain Component. Bottom: Simple Shear Strain Component. Note that simple shear still dominates, but is much more widely distributed than previous epochs. The velocity field is indicated by the arrows.
Epoch 5: Time step between photos 5 and 6 from the geology section. Top: Pure Shear Strain Component. Bottom: Simple Shear Strain Component. Note that the simple shear has become more focussed again as the wedge starts to deform substantially. Also note the appearance of a high strain zone well within the wedge.
Epoch 6: Time step between photos 6 and 7 from the geology section. Top: Pure Shear Strain Component. Bottom: Simple Shear Strain Component. Note that this epoch is still dominated by simple shear but that the strain is distributed into the terrane. This is observed in the photos as the appearance of thrusts in the terrane.
Epoch 7: Time step between photos 7 and 8 from the geology section. Top: Pure Shear Strain Component. Bottom: Simple Shear Strain Component. Note the broadly distributed simple shear strain as deformation steps outboard of the terrane. The terrane still experiences shortening, although it is more broadly distributed.
Epoch 8: The final state of strain. Top: Pure Shear Strain Component. Bottom: Simple Shear Strain Component. Note that simple shear still dominates and that it has once again become more concentrated at the toe of the new wedge.
Shear Strain Components