Finite strain estimates from the dalradian dolomitic formation, Islay, Argyll, Scotland

Sedimentary dykelets in the Dolomitic Formation of Islay have been rotated relative to bedding during the primary deformation, which imposed a penetrative, slaty cleavage on the dolomitic lithologies. The dykelets have been used to determine the principal strain ratios in two dimensions and, by a new method these results have been combined to define the three-dimensional finite strain state. The results show that the shortening normal to the cleavage is in the range 33–66%, and the maximum extension within the cleavage is in the range 25–157%. The deformation is predominantly of the flattening type (1 > k 0).