STRAIN MATRIX, 2D
As a result of the heterogeneity of geological materials, the deformation of a rock can be accomplished by differing mechanisms acting to different degrees on different parts or constituents of a crystalline aggregate. Different crystal species react in different ways to the stresses causing deformation as a function of the environmental conditions at the time of deformation. Components of bulk strain general strain mechanisms are crystalline plasticity, grain boundary sliding, pressure solution, rigid body rotation. It is a study that determines how much of each of these process played a part in the build up of the total or finite strain in the naturally deformed rock.
In naturally deformed rocks combinations of the processes mentioned above generally occur in differing proportions. They may act on different crystals in the aggregateThey may act at different times during the deformation history as environmental conditions change. As these various deformation mechanism become dominant at any given point at any given time within an aggregate, the strain is said to be locally "partitioned" into one or the other of these general mechanism.