A new method of determining finite strain in models of geological structures

Abstract

A new method of constructing models of cylindrical geological structures has been developed which allows the finite strain to be determined for each of a large number of small, initially square, elements. Each material layer is made up of uniformly thick, alternately colored laminations which are oriented vertically in one half of the model and horizontally in the other half. After the model has been deformed it is cut into slices perpendicular to the axis of the cylindrical structure, and the lamination patterns from the two model halves are superimposed graphically to reveal the strained shapes of the initially square elements. The three-dimensional finite-strain tensor of each element can be easily determined algebraically from measurements of its deformed shape, provided that the deformation involved rotation about no more than one principal direction. As an example the method is applied to a silicone putty model of a diapiric ridge which was formed by spinning the model in a centrifuge.