The marker field at different time

The marker field at different time steps during sinking of the block was used to calculate and plot distribution and magnitude of strain with the free software SSPX (Cardozo and Allmendinger, 2009), based on the grid nearest-neighbour method. More specifically, the marker field of a model at the initial (undeformed) and at a later (deformed) stage is overlain by a regularly spaced grid. Dilatational and maximum shear strain γ is calculated after Ramsay and Huber (1987) at the centre of each grid cell using a defined number of nearest neighbours. For additional details on strain calculation with SSPX, the reader is referred to Cardozo and Allmendinger (2009).